Other types of bioconcretions

Other types of bioconcretions
GUIDO BRESSAN · RENATO CHEMELLO · MARIA FLAVIA GRAVINA · MARIA CRISTINA
GAMBI · ANDREA PEIRANO · SILVIA COCITO · ANTONIETTA ROSSO · ANGELO TURSI
■ Platforms with coralline algae
The parts of a thallus, or whole thalli of
calcareous red coralline algae or
rhodophytes may come into contact
with each other and fuse together,
apparently due to their mineralisation.
They may also accrete and even
overlap occasionally or selectively (this
is called species specificity, still little
studied).
After a natural biotic synergic process,
Lithophyllum concretions
like that described above, occours
between the two species, the thalli may
adhere to a hard substrate, building a type of rock called bioconstruction.
These generally poly-specific bioconcretions are therefore the result of the slow
growth, overlapping and fossilisation of thalli, of which some - at least partly are dead. They may occupy large areas and give their colonised environment
particular morphological, biological and geological characteristics.
Coralline reefs are found at several bionomic levels and, when they grow in
shallow water where they are easily seen in the form of trottoirs (pavements,
or terraces), they become important landscape features and true natural
monuments. We can therefore imagine vermetid platforms, Lithophyllum
concretions and other littoral bioconcretions as horizontal spatial dilations of
superficial areas, which provide niches for species pre-adapted to intertidal
life.
The development of bioconcretions in specific areas of the Mediterranean
depends on climatic, hydrological and sedimentary conditions. The most
important builder species are Lithophyllum byssoides, Neogoniolithon
brassica-florida and Corallina elongata for large concretions, and Lithophyllum
(Titanoderma) trochanter, Tenarea tortuosa and Lithophyllum (Goniolithon)
papillosum for smaller, less evident assemblages.
Corallina elongata
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Lithophyllum byssoides, known in the past as Tenarea tortuosa, is made up of
round, cushion-like thalli 8-15 centimetres in diameter, with an alveolated
(honeycombed) surface due to its many adventitious, more or less erect
lamellae, joined together. Its colour ranges from pink to violet-grey. The thalli of
this alga, which may fuse together, firmly encrust rocky substrates and, when
the water is calm, these bioconcretions may emerge 20-30 centimetres above
the surface of the water.
Neogoniolithon brassica-florida has adhering, simple or encrusting thalli 2-5
centimetres across, sometimes covered by warty protuberances, with
coarsely lobed, frayed margins with thinned edges. Its colours vary from pink
and mauve-grey to ivory. This epilithic species, seldom found on old mollusc
shells, lives in the meso-infralittoral zone, but has also been reported at a
depth of 40 metres, in areas both exposed to and protected from currents.
Relatively euryecious, it can withstand changes in salinity, temperature and
light. It may therefore live in extreme conditions like those found in tide pools,
even permanent ones; it is never epiphytic and is an important component of
vermetid reefs (trottoirs).
Corallina elongata has articulate, erect, bushy thalli 1.5-5 centimetres high,
with regular, abundant, pinnate branches lying on a single plane; its
segments are compressed. The thalli vary in colour from pale pink to
greyish-violet, with paler margins on fresh specimens, and from violet-grey
Lithophyllum byssoides
to ivory white on dry specimens. This epilithic species lives in the mesoinfralittoral zone, on exposed rocks and in tide pools from the surface down
to 3 metres.
Lithophyllum (Titanoderma) trochanter has hemispherical, bushy, cushionshaped thalli, about 2.5 centimetres in diameter and 5 centimetres high, with
excrescences which are thin, fragile and erect, rising in all directions and
sometimes intermingled. Its thalli range in colour from grey to violet,
sometimes white. It lives in the meso-infralittoral zone, where it encrusts
vertical rocky rims exposed to waves and currents in well-illuminated areas. It
lives in permanent supralittoral pools, and sometimes in the infralittoral fringe.
It is generally found with Lithophyllum byssoides, Tenarea tortuosa and
Neogoniolithon brassica-florida.
Tenarea tortuosa has cushion-shaped thalli 20-25 centimetres in diameter
(occasionally only 10 cm) and a honeycombed surface with fragile, erect,
adventitious lamellae that are more or less anastomosed. They grow from a
basal crust covering the substrate at single points, and are thus easily
detached. The edges of its lamellae are always crumpled, sometimes slightly
thickened, with edges paler than the rest of the thallus. In colour, the thalli
range from pale pink to violet-grey, sometimes even yellowish and white.
Always submerged, it lives in the meso-infralittoral zone, although its many
alveoli do enable it to stay moist during brief periods of emersion.
It is sometimes found under the canopy of Cystoseira amentacea. Small
Ceramium species, Polysiphonia and Laurencia are often epiphytic on its
thalli.
Lithophyllum (Goniolithon) papillosum has thalli encrusting rocky substrates.
They have more or less regular, round protuberances (up to 2 mm in diameter,
3-5 mm high), and may sometimes be taller than they are wide, in which case
they are fragile. They may also more or less coalesce, in which case they are
wider, with typical pisolitic or cauliflower shapes.
From the viewpoint of the seascape and the geomorphological importance of
coralline algae in the Mediterranean, between the mesolittoral and deep
circalittoral there are:
● more or less evident bioconcretions, which sometimes reach imposing
sizes over the centuries and the resulting transformations of the marine
environment;
● smaller bioconcretions which, although scientifically important, may be
considered secondary due to their less conspicuous size;
● deep-water bioconcretions (treated elsewhere in this volume), which are
only visible to divers.
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Coralline bioconcretions
Clearly visible, sometimes large,
monumental concretions may be
subdivided as follows:
Rims (“encorbellements”) on
Lithophyllum byssoides.
Lithophyllum byssoides is the most
frequent assemblage in the Western
Mediterranean, and the one whose
structure and distribution have been
best analysed. In the course of time,
it has been defined in many ways,
according to variations in the
nomenclature of the dominant species:
Tenarea trottoir (rim), Lithothamnion
trottoir, Lithophyllum tortuosum
trottoir, Lithophyllum lichenoides
rims (also known by the French term
encorbellements) and, lastly,
Lithophyllum byssoides trottoir
Guido Bressan
Lithophyllum byssoides encorbellement.
The rims of L. byssoides are generally
found just above mean sea level,
in the mesolittoral zone, where waves
break. They develop on rocky calcareous,
volcanic or crystalline substrates which
are regularly wetted by tides and waves.
It is therefore the highest biological
construction of the benthic realm at sea
level. When the water is calm, the rims
emerge completely and their outer
margins may be as much as 20-30
centimetres above the water.
This condition is made possible by the
combined action of two factors which
allow the correct degree of moisture to
be maintained: exposure to waves, and
the porous nature of the calcareous
structure. The height above mean sea
level varies according to the force of
waves and/or the presence of cracks
and clefts which are vulnerable to
storms off the coast.
L. byssoides bioconcretions may
develop considerably in both width and
thickness. The simplest rims are dense
covers of thalli up to 20-30 centimetres
high, which may produce overhangs as
much as 1-2 metres wide. Here, the
upper surface is slightly depressed
in the middle and rises at the margin,
sometimes creating tide pools.
The development of these concretions
is such that two opposing rims over a
small inlet may eventually join, forming
a bridge.
The cross-section of well-developed
rims reveals three main parts, which
have been described in various ways
by different researchers who essentially
agree: the upper, outer layer is porous,
pinkish-violet, often beige-mauve,
formed by cushions of living algae.
They are never more than a few
centimetres thick and grow particularly
along the outer portion of the rim, with no
sedimentary deposits between branches.
The rim may have a honeycomb surface
due to anastomosed millimetre-long
crests, spines, or vertical lamellae of
similar length. When eroded, the
surface is furrowed.
Occasionally, the main bioconcretions
are covered by dense colonies of living
thalli adhering to the rock beneath.
This upper plate is made up of more
vital populations than those living
underneath. The outer, lower layer of the
rim is dead, and covered by sciaphilic
animals and algae. The inner structure
is composed of a hardened area of
varying thickness, produced by the
accumulation of fine debris between
the branches of the thalli. This fossilises
into a micritic mud of magnesium
calcite, which in turn forms a very
hard, microcrystalline cement.
This area, the heart of the rim, is made
up of concentric layers separated by
discontinuities, and actually looks and
feels like true rock.
When rims have large overhangs, their
lower surface, which is the shadiest
portion, is colonised by a sciaphilic
coenosis similar to that living in clefts
and caves. This “coralline area”, hosts
the same combination of species to
that living in deep water.
Organogenic formations in which
L. byssoides is dominant give rise to an
autonomous vegetal assemblage called
Lithophylletum byssoidis (sub. nom.
lichenoidis), with typical species: L.
byssoides, Chaetomorpha mediterranea,
Laurencia papillosa, Pterocladia
melanoidea, Lophosiphonia cristata
and Taenioma nanum. The interstitial
fauna is composed of various types
of destroyers (sponges of the genus
Cliona, molluscs of the genus
Lithophaga, etc.) which bore tunnels
into the rock, thus creating cavities
and weakening the structure.
Rims on Corallina elongata. Coralline
elongata is widespread on vertical,
shady, rocky walls, and grows from the
surface to depths of a few metres.
It is an infralittoral formation associated
with well-shaded walls near the surface
and exposed to the waves. Its rims
very often develop in the more poorly
illuminated area just below the
mesolittoral L. byssoides rims.
Unlike superficial formations, Corallina
rims do not develop into a single unit,
but give rise to parallel concretions.
Although sizes may vary and the rims
are generally not very firm (being less
than 10 centimetres in diameter), in
some cases - for instance, narrow, dimly
lit clefts in vertical cliffs - they may be
one metre wide and 40-45 centimetres
thick, and are so hard that they are
unaffected by hammer blows. The inner
structure is made up of tight stacks of
thin, pure white layers scattered with the
pink shells of Miniacina miniacea,
accompanied by barnacles, bryozoans,
etc. The nuclei of some Corallina rims
contain the cemented, eroded remains
of older rims which developed when the
sea level was lower, and which were later
enveloped and preserved by coralline
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algae when the sea level rose again.
These rims are often colonised by the
association Ceramio-Corallinetum
elongatae, whose typical species are
Ceramium elegans, C. ciliatum, C.
rubrum var. barbatum, Gelidium pusillum
and Anthithamnion cruciatum.
Rims on Lithophyllum trochanter.
These small rims do not have a particular
name. They are usually found in the
infralittoral zone (undertow area), on
well-illuminated, sloping, rocky walls
exposed to moderate wave action, and
occasionally also at mesolittoral level.
The rims look like round, wide, flat
cushions which, as they only adhere
to the substrate at a few points, are
easily detached.
This elegant species is at severe risk of
extinction. According to some scientists,
Lithophyllum trochanter (sub. nom.
byssoides) is a differential species in the
subassociation Lithophylletosum
trochanteris (ex byssoidis).
Bioconstructions on Lithophyllum
(Goniolithon) papillosum. These
formations are not very evident, and
develop in the lower mesolittoral as
compact, pinkish-violet encrustations
growing on living organisms.
They may be of various widths but are
not very thick (between a few millimetres
and 2 centimetres). The species is
generally found in sunlit areas, along
coasts exposed to waves (it does not
seem to withstand total submersion
very well). However, it cannot grow in
areas where the light is too strong for
it to develop together with N. brassicaflorida, with which it may be confused
at first sight.
It is often found in specific combinations
- for instance, in addition to N. brassicaflorida, with L. byssoides and other soft
species. According to some scientists,
Lithophyllum papillosum, Polysiphonia
opaca and P. sertularioides give rise
to the association PolysiphonioLithophylletum papillosi.
Bioconstructions on Tenarea tortuosa.
This species is usually found among the
superficial populations of the photophilic
infralittoral, from sea level down to 4-5
■ Vermetid reefs
Vermetid platforms, or reefs, are built by the gastropod mollusc Dendropoma
(Novastoa) petraeum, in association with some encrusting red seaweeds like
Neogoniolithon brassica-florida. These reefs are often colonised by Vermetus
triquetrus, another species of vermetid which, in both solitary and gregarious
forms, occupies the portions of the structure that are permanently underwater.
The upper limit of the reef is colonised by the red alga Lithophyllum byssoides.
The bioconstructing vermetid is a highly gregarious species living in the tidal
zone, to which it is particularly well adapted, thanks to the horny operculum
that seals its shell opening in an airtight manner, thus enabling the animal to
tolerate periodic emersions between tides. Direct development of the eggs,
which are incubated in the mantle cavity and hatch into young that can crawl
into their mother’s shell to colonise it, gives this species a certain advantage
over other probable competitors for space, and guarantee the continuous
growth of the platform structure.
Vermetid reefs colonise the tidal zone exclusively on rocky coasts, with smaller
formations according to the type of rock: calcarenite, limestone, dolomite,
basalt and flysch. The presence of an abrasion platform thus becomes the
essential condition for the formation of a reef. A second factor limiting the
distribution and size of structures on a small scale is the extent of superficial
Tenarea tortuosa concretions
metres. This bioconstruction is made
up of round, brittle pulvini 2-4 cm in
diameter (maximum 10 cm), the thalli
of which adhere to the substrate at
only a few points (like T. byssoides) and
may therefore easily be broken off by
hand. Tenarea tortuosa, being rare,
delicate and elegant, is also threatened
with extinction, precisely because it is
collected too often.
The coralline alga Neogoniolithon with the vermetid Dendropoma petraeum
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hydrodynamics, as developed reefs are unlikely to be found in sheltered
environments with calm waters. For instance, in Sicily, vermetid reefs are only
found along the north-western coasts, and only small formations grow in the
north-east. Lastly, the slope of the coast also affects the shape and size of
reefs. Large platforms develop on slopes with gradients between 15° and 40°.
The geographical distribution of vermetid reefs in the Mediterranean shows
that they live in waters with mean temperatures that are never lower than 24°C
in summer and 14°C in winter, with a northern limit crossing the 38th parallel
north. Such reefs therefore develop in the central-eastern part of the
Mediterranean, and the largest formations are generally found off the coasts of
Israel and Lebanon. In the Western Mediterranean, vermetid reefs are only
found in Algeria, Spain and the Italian islands. Mainland Italy does not host
true vermetid reefs, although some structures are known on the island of
Licosa (Campania), and the species has been reported as far north as the
island of Ischia, the coasts of the Gulf of Naples and north-eastern Sardinia.
However, the most imposing reefs colonise the Tyrrhenian coast of Sicily.
General morphology of reefs. Study of the Sicilian reefs and of published
material allows us to draw up a general morphological scheme, which may be
represented along a transversal section of the coast towards the open sea,
along which the following components are found:
Emerged vermetid reef
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INNER MARGIN
POOL
OUTER MARGIN
CREST
POOL
FRINGE of
Cystoseira amentacea
Morphological diagram of a vermetid reef
● a proximal rim, a few centimetres thick (often absent), made up of
Neogoniolithon brassica-florida crusts and mamellonar (rounded) cushions of
Lithophyllum byssoides, considered as a marker of the upper reef;
● a crust composed of Dendropoma petraeum, indicated as an inner margin,
which is a few centimetres thick and between a few centimetres and less than
one metre wide, according to exposure to waves;
● one or more depressions in the reef, called cuvettes, or rock-pools, between
a few centimetres and more than one metre in diameter, and about 50
centimetres deep. When they are particularly large, rock-pools are like small
inner reefs or reef flats, colonised by small patches of Posidonia oceanica and
photophilic algae;
● an outer margin, made up of a thick, articulated, fissured crust of
Dendropoma, sometimes more than 40 centimetres wide, which represents
the true active portion of the reef, expanding upwards and seawards;
● an infralittoral fringe with rainbow bladderweed, Cystoseira amentacea var.
stricta (synonymous with Cystoseira stricta), growing below the outer edge of
the reef.
How many types of reefs are there? The simplest vermetid structure is a crust
(i.e., one or a few layers of thin vermetid shells) and is found along many
Mediterranean coasts, even where conditions do not allow the development of
a true reef. True Dendropoma formations in the Mediterranean have four typical
features: the framework, which develops along the coast, the reef crest, and the
outer reef, or forereef, which may either slope steeply or be greatly exposed to
wave action. The structure is generally less than one metre wide and 10-20
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centimetres thick along the outer margin. Both frameworks and simple crusts
are the most common formations along coasts subjected to primary
colonisation, like volcanic islands and large boulders resulting from landslides.
Frameworks are also found in areas which have long been colonised but where
the development of a true reef is partly or completely hindered by unfavourable
coastal morphology or reduced exposure to wave action.
The second type of reef (in terms of complexity) is the true reef, which is very
similar to the fringing reefs built by tropical madrepores. These reefs may be
up to 10 metres wide and, along the outer edge, up to 45 centimetres thick.
Their lower part, on which the outer margin leans, is continually eroded and
eventually forms a steep step between 40 centimetres and more than one
metre high. This type of morphology is common to 90% of all Sicilian vermetid
reefs and most of those in Spain and Israel.
A particular type of morphology is that of mushroom-like pillars, which are
perhaps the result of two different processes of formation. Generally,
mushroom shapes are caused by differing degrees of resistance to
mechanical (and probably chemical) erosion of the rocky formations and of the
vermetid reefs being constructed above them. The mother-rock is eroded
more quickly than the concretion, which in turn compensates for the erosion
by growing continually along its outer margin. When the process reaches an
advanced stage, the structure looks like a wide-brimmed hat growing on a thin
support (the “stalk”). The second shape is created when vermetid reefs
develop on abrasion boulders which have fallen to the base of the slope. Over
time, as the structure evolves, the boulder and the framework are eroded in
different ways, creating a mushroom shape. Series showing these two
processes are visible along the rocky coasts of north-western Sicily, but still
need to be described for other Mediterranean areas.
The last known morphology is that of the micro-atoll, which has been described
along the coasts of Israel. It is seldom found in the Western Mediterranean,
where it is often confused with the mushroom-shaped pillars.
The role of vermetid reefs. For true understanding of the role played by
vermetid reefs, we should first note those areas where they do not occur. The
marine populations of reef-free rocky coasts are neatly arranged along vertical
gradients, regulated by hydrodynamic energy, tidal variations and coastal
morphology. The composition of these populations is always the same, almost
predictable, and more or less limited to two dimensions.
Along rocky coasts where vermetid reefs develop parallel to the surface of the
sea, animal and plant populations are distributed in a three-dimensional space,
the third dimension being the width of
the reef. In these conditions, there are
more ecological “opportunities” for
animal and plant species of the
mesolittoral and upper infralittoral
zones, and this gives rise to a complex
mosaic system in which hundreds of
invertebrates and dozens of fish species
find food, refuge and protection from
predators.
Thus, the inner and outer edges of
reefs host typically mesolittoral animals
Padina pavonica
and plants, and the most diversified
infralittoral populations are found in
rock-pools. This different distribution influences biodiversity and although no
research has yet been carried out on the biodiversity of vermetid reefs, it may
be inferred by examining single groups sampled at different times in various
Mediterranean regions.
There are more than 100 species of algae distributed over the various sections
of a reef. The structurally most important ones are the calcareous rhodophyte
Negoniolithon brassica-florida, which contributes towards consolidating
concretions by cementing tubules of Dendropoma petraeum, and Lithophyllum
byssoides, which may form crusts or pulvini at both ends of the reef. The group
of species of the genus Laurencia (Rhodomelaceae family), Padina pavonica
and a few species of Cystoseira and Dyctiota occupy the shallow pools of the
inner reef. In areas affected by human activities, these species are replaced by
coralline algae and green algae (Ulvaceae). Deeper rock-pools - seldom more
than 50 centimetres at low tide - are colonised by encrusting red seaweeds and
Halimeda tuna.
The belt with Cystoseira amentacea var. stricta develops just below the outer
margin of the reef, near the upper infralittoral fringe, below which are
populations rich in species adapted to high levels of hydrodynamism.
The inner portions of the reef and each macroalgal group host a particular
associated animal population. All animal groups associated with the phytal
system and rock populations colonise reefs.
There are about 50 species of molluscs; typical of the various portions of the
reef are Mytilaster minimus, Cardita calyculata, Lepidochitona caprearum,
Onchidella celtica and Patella ulyssiponensis in the inner and outer margins
and in crests; Patella caerulea, Pisinna glabrata, Eatonina cossurae and
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Barleeia unifasciata prefer rock-pools. The inner margin now usually hosts
increasing numbers of the alien bivalve Brachidontes pharaonis, which often
replaces M. minimus.
There are about 70 species of polychaetes living in Sicilian reefs, and their
distribution is influenced by the horizontal extent of the reef itself. Most
species are camouflaged and find refuge in the empty shells of vermetids and
in the fissures and crevices of the reef, and a smaller group is associated with
the algal groups living in rock-pools. Dominant species are the nereidids
Perinereis cultrifera, Platynereis dumerilii and Palola siciliensis, and several
species of Lumbrineris, Syllis and polynoids.
Although crustaceans are less well-known, research has recently been carried
out on the spatial distribution of the decapods Pachygrapsus maurus, P.
transversus and P. marmoratus, their predator Eripha verrucosa, and their
competitor, the alien species Percnon gibbesi. Another species typical of Sicilian
reefs is the hermit crab Calcinus tubularis, which settles in the empty shells of
Dendropoma. Research carried out along the coasts of Israel has identified 36
fish species associated with Dendropoma petraeum reefs, four of which are of
Eritrean origin, introduced into the eastern Mediterranean basin when the Suez
Canal was opened. The strictly benthic fish population is typically Mediterranean
and is made up of 18 species. The most numerous are blennies, gobies and
three-fin blennies, with nine, four and three species, respectively. The
camouflaged blennies Parablennius zvonimiri and Scartella cristata are the most
numerous, together with Tripterygion tripteronotus, T. delaisi and T. melanurus.
There are 16 other nekto-benthic species and even two pelagic species.
Recent research shows the existence of two different biocoenotic groups,
separated into mesolittoral and infralittoral components. The former is more
important in clearly defined areas of the reef, especially along the outer and
inner margins and in crests, which are higher than the reef itself. Rock-pools in
the inner reef host definitely infralittoral groups, because they manage to retain
a little water at low tide, and are thus able to host populations from the upper
infralittoral.
In conclusion, the most interesting aspect of vermetid concretions is its
horizontal extension, which creates the third dimension along which populations
are distributed. This in turn depends on distance from the sea, exposure to
waves, and the relative height above mean sea level - all factors that influence
the wetting of single portions of the reef. These formations are therefore
particularly interesting, especially for their irregular distribution, which is a
compromise between the vital requirements of builder organisms and
competition with other populations living in the meso- and infralittoral fringes.
The trottoirs may therefore be viewed as a spatial dilation, providing additional
or amplified habitats for species capable of colonising areas far from their
original biotopes.
Cystoseira amentacea var. stricta
Patella ulyssiponensis
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■ Polychaete reefs
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Polychaetes, in particular two species, Ficopomatus enigmaticus and
Sabellaria alveolata, are among the many organisms producing concretions,
respectively in brackish and coastal environments. Although the ecological
role they play is very similar - both are “engineer species”, i.e., builders of the
marine habitat, and their biogenic concretions are very similar - they have
different ecology and distribution, and some characteristics of their reefs
require them to be described separately.
Ficopomatus enigmaticus reefs
Reefs of Ficopomatus enigmaticus. The polychaetes of this species, also
known as Mercierella enigmatica, are marine tubeworms that build extensive
concretions formed of the mass of calcareous tubes which they produce.
These tubes, within which the single worms live, are attached throughout their
length to a hard substrate, or grow vertically, intertwining with one another.
Thanks to this characteristic and to the gregarious behaviour of these animals,
sometimes very extensive tube aggregates can be built up.
F. enigmaticus, belonging to the serpulid family, is found all over the world,
although it is thought to be native to the Indian Ocean coasts of Australia, from
which it spread to all temperate areas, presumably transported on the hulls of
ships. It was first found in the Mediterranean in the 1920s, and since then has
colonised the entire basin. It produces cylindrical tubes which are generally 2025 mm long, but which may reach 30-50 mm and diameters of 1.5-2 mm. The
larger specimens have tubes which flare out at irregular intervals towards their
distal extremities. From the surface of the sea to depths of 1-2 metres, the
species adheres to hard substrates of all kinds and sizes, ranging from shells,
reeds, piles, and quayside and dockside structures, to the hulls of ships. The
species is particularly tolerant of variations in salinity, adapting to both
oligohaline (low salinity) and hyperhaline (high salinity) waters. It can withstand
high rates of eutrophication, and is sensitive to wave action and intense
hydrodynamics.
Ficopomatus reefs develop exclusively in brackish environments, where they
form belts, barriers and reefs up to one metre thick and from a few dozen
centimetres to several metres wide. They may also be built in the middle of
shallow brackish basins, and look like large mushrooms adhering to fragments
of hard substrates (shells, branches, rocks, reeds, etc.), sometimes reaching
the surface of the water. They may extend for hundreds of square metres and
are produced by many generations of tubeworms all growing attached to one
other. Their gregarious behaviour is also favoured by the fact that the larvae
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develop inside the bodies of their parents, and are only later released into
the water.
Ficopotamus reefs form very quickly and grow at speeds of up to 30
mm/month. After an initial phase of rapid development, the outer portions of
the reef may collapse under their own weight, although this initial fragility is
soon overcome by new, fast colonisation by young individuals, which further
consolidates the base of the concretion. Only the superficial layer, which is
about 10 cm thick, is made up of tubes hosting living organisms; the tubes
underneath do not contain worms but sediments.
Although Ficopomatus is a primary builder, because its tubes make up the
framework of the concretion, other organisms also contribute as secondary
constructors. For instance, several species of barnacles (Balanus eburneus, B.
improvisus, B. amphitrite) carry out construction work, and many mussels
(Mytilaster lineatus, M. marioni) use their byssi to adhere to the Ficopotamus
tubes, thus increasing the surface area the whole. Yet other organisms stabilise
the concretions, like the bryozoan Conopeum seurati, whose encrusting
colonies efficiently consolidate the tube aggregates, thus increasing the rigidity
and cohesion of the entire structure. Reefs may also host many isopod
crustaceans such as Lekanesphaera hookeri, L. monodi, Sphaeroma serratum
and Cyathura carinata; amphipods - with many species of corophiids
(Corophium insidiosum, C. acherusicum); gammarids (Gammarus aequicauda,
G. insensibilis); other polychaetes, like Hediste diversicolor, Neanthes succinea
and Polydora ciliata; the larvae of chironomid dipterans; and other species of
colonial organisms found adhering to hard substrates, like the hydrozoan
Cordylophora caspia, the bryozoan Bowerbankia gracilis, and the tunicate
Botryllus schlosseri.
The Ficopotamus type of concretion does not have any true destroyers,
although fish, especially mullet and gobies, nibble at its margins to feed on the
invertebrates inhabiting them. Thanks to their particular technique for catching
food, typical of filter-feeders, the millions of Ficopotamus individuals per cubic
metre in the reef remove particles of organic matter from the water, thus
affecting its transparency and trophic conditions. But reefs can also affect the
entire ecosystem by increasing biodiversity, which does not occur exclusively
by colonisation on the part of small invertebrates, but also because, thanks to
them, species of great conservationist value visit lagoons, like the blackstriped pipefish (Sygnathus abaster), Mediterranean killfish (Aphianus
fasciatus) and the typical lagoon goby (Knipowitschia panizzae), an interesting
Mediterranean endemic. In the multitude of nooks and crannies, fish find both
living space and abundant food resources.
Reefs of Sabellaria alveolata. The polychaetes of the genus Sabellaria,
belonging to the Sabellariidae family, are a particular group of sessile
tubeworms which are able to cement sand efficiently. Some species can
therefore produce imposing concretions, true organogenic cliffs extending
along temperate and tropical coasts all over the world. In the Mediterranean,
the honeycomb worm Sabellaria alveolata is the only species capable of
building concretions so large that they may be defined as reefs. Two other
Sabellaria species, S. spinulosa and S. alcocki, have been found in Italian seas,
but they form small aggregates rather than true reefs.
Like Ficopotamus, Sabellaria is gregarious, and it is precisely by aggregating in
huge numbers that it builds its typical concretions of cemented sand. These
look like honeycombs, hence the scientific name of the species (Sabellaria from
sand, and alveolata from honeycombs). They are massive and globular in shape
and, when local water movements are strong, become even more encrusting
and flattened. An adult tube may be longer than 30 centimetres and have a
diameter of half a centimetre.
According to the limited data available, tube size depends on density, and
ranges between 53 and 475 individuals/dm3, according to the orientation of the
formation itself. When it is vertical, density increases; when it is horizontal,
density decreases, perhaps due to disturbance by sedimentation or abrasion
caused by sediments. Single tubes grow vertically, and new individuals either
Sabellaria alveolata reefs
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106
overlap or join at the sides of the
structure, which can thus accrete
massively. This process is made
possible thanks to the interesting
method adopted by honeycomb
worms to enable their larvae to
colonise tubes inhabited by adults. The
adults emit special substances that
stimulate the larvae and induce them to
attach themselves near adults. Other
gregarious organisms like barnacles
also use this efficient strategy.
Along the coasts of Italy, Sabellaria
reefs are found in Campania (Gulf of
Naples, Salerno and Policastro),
Liguria, Tuscany, Latium and Sicily. The
species colonises very superficial
Mytilus galloprovincialis
coastal areas, from the low tide mark
down to 3-5 metres, where wave action is stronger and moves particles of the
sediments which are used by the worms to build their tubes. It also provides
the organic matter on which these filter-feeders live. Sabellaria reefs are
generally found along exposed sandy coasts, although their concretion does
need a rocky base to start with (it may even be an artificial substrate, such as
rubble or dockside structures, or small stones). The coasts of Tuscany and
Sicily have Sabellaria reefs contained within Posidonia meadows, giving rise to
an interesting environmental mosaic.
Sabellaria reefs host vagile, sessile and sedentary organisms like encrusting
seaweeds, other polychaetes, molluscs, bryozoans and sea squirts. Examples
of sessile and sedentary forms are the macroalgae Ulva sp. and Enteromorpha
spp.; invertebrates are the polychaetes Sabellaria alcocki, Lanice conchilega,
Teberella lapidaria, Cirriforma filigera and Notomastus lineatus; the serpulids
include Pomatoceros lamarcki and species of the genus Hydroides, and the
bivalves Striarca lactea, Arca noae, Mytilus galloprovincialis and Mytilaster
minimus. Many of these species are commonly found on hard substrates, and
Sabellaria provides them with firm support. Unlike Ficopomatus reefs,
Sabellaria reefs do not contain many bioconstructing and cementing
organisms, because the tubes of agglutinated sand offer less resistance and
have different textural characteristics with respect to the calcareous substate,
even though they are biogenic.
Vagile forms include many polychaetes, like syllids, phyllodocids (Eulalia viridis,
Eumida sanguinea), nereidids (Perinereis cultrifera, Nereis falsa), esionids and
lumbrinerids (Lumbrineris spp.). In particular, there are many peracarids, like the
tanaids Apseudes latreilli and Leptochelia savignyi, the isopod Gnathia
phallonajopsis, and amphipods such as Maera inaequipes, Jassa marmorata, J.
ocia, Corophium sextonae, C. acherusicum and C. acutum. These species are
generally found on mixed or sandy substrates exposed to wave action.
The density of Sabellaria reefs has been reported to be inversely proportional to
the abundance and diversity of fauna associated with them. High densities of
polychaetes compete with other organisms, especially in filtering food. When
density is lower, competition is reduced, and empty tubes are soon occupied
by other organisms. As already mentioned, Sabellaria reefs are not known to
host many destroyers, as their main destructive agents are excessive water
motion, the abrasive action of sediments in suspension due to wave motion
and, when the hydrodynamic regime changes completely, excessive
sedimentation.
Reefs of S. alveolata, like those of Ficopomatus, carry out important functions
for the marine environment, such as potential bioremediation of water. As a
filtering organism, Sabellaria removes sediments and particles from water,
although the ecological impact of this is very restricted, due to the extremely
dynamic environment in which the species lives.
The polychaete Lanice conchilega
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108
■ Reefs of Cladocora caespitosa
Cladocora caespitosa is a colonial zooxanthellate coral of the Favidae family,
and one of the few hermatypic madrepores (reef-forming species depending
upon zooxanthellae for food) of the Mediterranean. It is often found along
coasts in shallow water and as far down as 30-40 metres. Its round colonies,
between 10 and 30 centimetres in diameter, grow on solid substrates in very
different environments: near the mouths of rivers, in Neptune grass
meadows, and in coralligenous habitats. Although there are generally only a
few isolated colonies, when their density and size increases, they may join
together and give rise to extensive banks.
Cladocora caespitosa is a type of coral called phaceloid, i.e., the individuals
making up the colony (polyps) are not in contact with each other and develop
a tube-shaped skeleton (corallite) about half a centimetre in diameter which,
due to the constant deposition of calcium carbonate, grows vertically.
Colonies grow extremely slowly, from a few millimetres to about half a
centimetre a year, and colonies 50 centimetres in diameter may be 100-150
years old.
Their age is estimated by means of sclerochronology, i.e., radiographic study
of physical and chemical variations in the corallites. X-ray analysis shows
alternating denser (dark) and less dense (light) bands, corresponding to the
deposition rates of calcium carbonate throughout the year. The polyps
deposit the darker bands of calcium carbonate in autumn-winter and the
lighter ones in spring-summer, so that each pair of bands corresponds to a
period of about one year.
Cladocora caespitosa is one of the most ancient Mediterranean corals, and
its remains have been found in fossil deposits going back to the late Pliocene.
It is also a reliable climatic indicator.
The most important fossil deposit of Cladocora in Italy is off Santa Teresiola
(Taranto, Apulia) where, thanks to phenomena of geological uplift, a bank
about 125,000 years old is visible, extending for 0.6 km2.
Today, living banks of such size are hardly ever found in the Mediterranean.
The most frequently analysed bank is in Croatia, at depths between 6 and 18
metres and covering an area of 0.65 km2. It is composed of many colonies
which aggregated into a single one, now about half a metre high, giving rise
to a flat, almost uninterrupted bank of coral. At present, the survival of this
bank, which is a true natural monument, is jeopardised by two factors
associated with climate change. One is proliferation of the green alga Caulerpa
racemosa, which in summer increasingly covers the polyp colonies, killing
them. The other is the rise in water temperatures which may reach 29°C and
which causes the polyps to undergo excessive heat stress and die, like the
corals in tropical areas.
Biogenic construction with Cladocora caespitosa
Cladocora caespitosa
109
110
■ Infralittoral and
bryozoan concretions
circalittoral
With a total of 480 known species,
bryozoans are a very important benthic
group of Mediterranean fauna. Many
species have more or less mineralised
calcium carbonate skeletons and
develop quite large colonies. They are
Colony of bryozoans (genus Pentapora)
therefore potentially suited to form
concretions, both as primary builders by constructing the supporting framework, either alone or with other
organisms, mainly algae, serpulids and corals - or by playing secondary roles
according to differing functional categories.
The most important species of primary builders are those with rigid, erect, treelike skeletons and others with multi-layered encrusting skeletons, which form
dense crusts. These adapt to the ruggedness of the substrate by folding and
overlapping in various layers and sometimes even incorporating other organisms.
Among them are some perennial species which grow rapidly and continually,
like Pentapora ottomülleriana, Schizoporella spp., Schizomavella spp.,
Schizobrachiella sanguinea, Parasmittina spp., Rhynchozzon spp., Calpensia
nobilis and Reptadeonella violacea. In the infralittoral, these species encrust living
organisms, rocks, organogenic concretions and various types of substrates.
The genus Schizoporella has always built concretions (both fossil and presentday ones) which extend for several metres and are several dozen centimetres
thick in shallow, calm waters rich in organic matter (like S. errata in ports) as
well as in more turbulent areas. The species is known to modify its building
techniques - from thick encrustations to erect, branched build-ups - according
to water movements and the presence of other erect carbonate organisms,
which it covers. A similar building technique is used by Calpensia nobilis, a fastgrowing bryozoan (8 cm a year in length) which envelops Posidonia rhizomes,
forming dense “sleeves” up to 13 cm tall and a few centimetres thick in
meadows with flowing water. If these then coalesce with nearby sleeves, they
may give rise to large concretions. C. nobilis also forms unattached bryolites
(similar to rhodoliths), augmenting the colonies around organic and inorganic
nuclei on loose sandy-gravelly bottoms. At greater depths, concretions are
formed by species of the genus Parasmittina.
Particularly interesting bioconcretions are formed by large erect bryozoans like
Pentapora spp., Reteporella spp., Smittina cervicornis, Adeonella spp. and
Myriapora truncata. They may grow on both shaded banks and loose
substrates, giving rise to the platform coralligenous.
In all these cases, the large organogenic concretions created by bryozoans
increase the complexity of the environment, providing new niches and
enhancing local diversity. Lastly, although very small, also of interest are the
nodular veriform reliefs on the walls of caves of Celleporina mangnevillana and
the small overlapping colonies of various bryozoans such as Puellina
pedunculata, P. corbula, Plagioecia inoedificata, P. platydiscus and Setosella
cavernicola produce interesting nodular or worm-like reliefs on the walls of
underwater caves.
At present, bryozoan concretions are not protected in either Italian or
Mediterranean waters. However, the facies with coastal debris with large
bryozoans (DC/b) has been associated with coralligenous habitats and is
included in initiatives aimed at implementation of the UNEP Action Plan for
protecting coralligenous assemblages and other calcareous concretions in the
Mediterranean by countries which are signatories to the Barcelona Convention.
It should be noted that some species, especially large, erect, arborescent ones
growing in water easily reached by human swimmers and divers, are
particularly vulnerable and should be specifically protected, in the light of the
“Strategic action programme for the conservation of biological diversity”.
■ Deepwater coral reefs
Deepwater white corals, especially
Lophelia pertusa and Madrepora
oculata, make up the complex basic
structure of a biocoenosis living on
muddy bathyal ocean beds and on the
bottom of the Mediterranean.
These are true “hot spots”, treasure
Colony of Madrepora oculata at a depth of 500
troves of biodiversity, irreplaceable but
metres
at the same time extremely vulnerable
biota at these depths. Unlike tropical species, white corals live at very deep
down and therefore do not host symbiontic algae. In the Mediterranean, they
form three-dimensional banks of varying sizes which contain many vertebrates
and invertebrates of great scientific and commercial interest.
White corals have lived in the Mediterranean since ancient times, perhaps as
long ago as the Miocene (approximately 22 to 5 million years ago). At the end of
that period, with the beginning of the Messinian, when vast areas of the
111
112
Mediterranean basin dried up, many
species living in it became extinct. In
the Pliocene. when a passage to the
Atlantic Ocean opened, after the
Mediterranean re-expanded, the sea
once again became populated by many
Atlantic species, among which there
were certainly white corals, which
spread and developed during the
The bivalve Spondylus gussonii
following Pleistocene glacial periods. At
the present time, apart from a few
exceptions, like the white coral bank of Santa Maria di Leuca (Apulia), these
colonies are either extinct or greatly reduced. Of the three species composing the
biocoenosis - Lophelia, Madrepora and Desmophyllum - Lophelia is the weakest.
The biocoenosis of deepwater white corals with the three species mentioned
above is found in all oceans. In the Mediterranean, fossil reefs extend from
Spain in the west to the island of Rhodes in the east. Although the fossil or
subfossil remains of these corals are widespread, very little is known of currently
living reefs of Lophelia and Madrepora. There are perhaps more colonies than
those of the two locations mentioned in the literature. Recent studies report the
occurrence of white coral reefs also in the areas of Santa Maria di Leuca, the
Strait of Sicily, the Tuscan seas and the Gulf of Genoa. Although it is regressing
strongly, the biocoenosis of white corals in the Mediterranean is generally
found between 250 and 2500 metres and gradually shrinks eastwards, where
the warmer water temperature may be a limiting factor.
Deepwater white corals are pockets of biodiversity of the Mediterranean bathyal
zone, which for centuries had been considered devoid of any form of life. In the
Ionian Sea, the reef of Santa Maria di Leuca, alone, contains more than 220 living
species. Sponges, molluscs and cnidarians are the largest groups, followed by
bryozoans and anellids, which are a source of food for the many decapods and
fish species living in this biocoenosis. The most frequent species found here are
the sponges Desmacella inornata, Pachastrella monilifera, Poecillastra
compressa, Spiroxya sp. and Cliona sp.; the cnidarians Lophelia pertusa,
Madrepora oculata, Desmophyllum dianthus (= cristagalli) and Stenocyathus
vermiformis; the anellids Eunice norvegica, Filogranula gracilis, F. stellata,
Harmothoe vesiculosa and Subadyte cfr. pellucida; the bivalves Delectopecten
vitreus and Spondylus gussonii; and the decapods Bathynectes maravigna,
Munida intermedia, M. tenuimana and Rochinia rissoana. Typical cartilaginous
fish are Chimaera monstrosa, Etmopterus spinax and Galeus melastomus,
and bony fish are Caelorynchus
caelorhyncus, Helicolenus dactylopterus,
Hoplostethus mediterraneus, Pagellus
bogaraveo, Micromesistius poutassou
and Phycis blennoides.
The exact structure and true species
composition of this biocoenosis are
objectively difficult to identify, due to its
great structural fragility, which means
that invasive sampling methods cannot The crab Bathynectes maravigna
be used. In the Mediterranean, deepwater white corals are like oases in a desert. Their three-dimensional structure
gives rise to myriads of micro-environments, favouring colonisation by several
endo- and epibiontic species. In addition, as trawling for fish is impossible,
because nets and other equipment are easily damaged or lost, white coral reefs
provide refuges or “spill-over” areas to many vagile species, including those of
commercial interest, like crustaceans and several types of fish.
Even experts find it hard to distinguish live white corals from fossil or subfossil
ones as, for instance, fragments of Pleistocene white coral may be buried
under layers of fine sediments and have maintained the bright white colour of
living specimens. By contrast, in other areas, the same skeletons may be
partially or totally covered with a film of iron and manganese, which turns them
grey. Live white corals can only be identified by the presence of polyp tissue or,
if living specimens are placed in seawater immediately after being sampled,
they release a particular mucous film that floats to the surface. In one
laboratory, white corals managed to survive for more than three months when
kept in the dark at a temperature of 13°C and fed on freeze-dried plankton.
Another characteristic species of this biocoenosis is the polychaete anellid
Eunice norvegica, whose delicate parchment tube becomes completely covered
by madrepores over time, thus forming true tunnels inside the mass of coral.
Mediterranean deepwater white corals are very important for several reasons:
● paleontologically: their ancient origin and the fact that they have lived
through many geological eras makes them very interesting species, particularly
from the genetic viewpoint;
● ecologically: the high number of species living in this biocoenosis is
conspicuous in the bathyal zone where they live;
● productively: these areas contain commercially profitable fish species which
are impossible to catch, and they therefore become spawning and nursery
areas for several species, to the later benefit of fishermen.
113
Conservation and management
FRANCESCO CINELLI · GIULIO RELINI · LEONARDO TUNESI
■ Regulations concerning protective
measures
European Council Directive 92/43/EEC
on the conservation of natural habitats
and of wild fauna and flora, together
with the Italian enforcement of another
Directive (DPR 357/97 of 8/09/1997 and
further amendments) is the most
important and binding set of regulations
for the protection of nature, partly
because failure to comply with them
Mediterranean slipper lobster (Scyllarides latus)
implies sanctions and may even
become an offence.
However, the Habitats Directive focuses on terrestrial habitats more than on
marine ones and, of the 217 habitats of EU interest, only nine are marine and
only two are true habitats - intended as biotopes (i.e., areas hosting
biocoenoses). Most of them are geographical and/or geological areas, like
lagoons, estuaries, bays, “sandbanks which are slightly covered by sea water all
the time”, or “rocks”. The communities living in these locations may change
substantially according to depth, type of rock, irradiance, etc.
None of the organogenic calcareous concretions is mentioned, in spite of their
great importance in Mediterranean biodiversity. The same applies to species.
Although Annex B (II) contains a list of species for which protected areas are
required, only 17 out of 223 animal species (12 of which live in Italy) are marine
and Mediterranean (no invertebrates are included), and none of the 370 plants
listed are marine. Annex D lists only four species in need of protection, and
Annex E mentions only two species which may require management measures:
red coral (Corallium rubrum) and the Mediterranean slipper lobster (Scyllarides
latus). Strangely enough - because this particular Annex only refers to species
exploited by man - two coralline algae are also listed: Lithothamnion corallioides
and Phymatolithon calcareum (= Lithothamnion calcareum).
Dusky grouper (Epinephelus marginatus)
115
116
As Annex A (I) of the Directive does not contain either calcareous biogenic
concretion habitats or species living in them according to Annex B (II), no
provision has been made for Sites of Community Importance (SCI) or Special
Areas of Conservation (SAC). Therefore, there are no legal instruments for the
protection and conservation of these plants and animals, unless they already live
inside Protected Marine Areas (PMA). However, there is room for hope, as a new
Interpretation Manual of European Union habitats allows for the inclusion of many
bioconstructions in reef habitats. The Convention on the Conservation of
European Wildlife and Natural Habitats (Bern, 1979) was ratified by Italy in 1981
(Law 503 of 5/08/1981), but it was only after 1996 that its Annexes regarding plant
and animal species to be rigorously protected were modified and amended.
Among the macrophytes (Annex I) which are mentioned in this volume, there
are the calcareous seaweeds Goniolithon byssoides - now Lithhopyllum
(=Titanoderma) trochanter - and Lithophyllum lichenoides. Among the animals
listed in Annex II, which are also found in coralligenous systems, there are some
molluscs, sponges and coelenterates, like Astroides calycularis and Savalia
savaglia (=Gerardia savaglia). The molluscs include Dendropoma petraeum, the
main builder of vermetid reefs. It should be emphasised that rigorous protection
of the species listed in Annexes I and II also requires protection of the habitats
in which they live. Unfortunately, the Bern Convention does not have the
enforcing power of the Habitats Directive.
An essential contribution in compensating for the shortcomings of the Habitats
Directive as regards the marine environment comes from the Barcelona
Convention (1995). Among its various protocols, there is also the “Protocol
concerning Specially Protected Areas and Biological Diversity in the
Mediterranean” (SPA & Biodiversity Protocol/SPA/BIO) which, surprisingly, is
not limited to territorial waters. All the signatories are required to create
specially protected areas for the conservation of habitats and species, and also
Specially Protected Areas of Mediterranean Importance (SPAMI).
The criteria for which an area becomes a SPAMI include the presence in these
sites of rare, endemic or endangered species, their ecological importance,
degree of biodiversity, natural state, special habitat characteristics, and
scientific and cultural importance.
From a bionomic point of view, the benthic realm in the Mediterranean Sea
(see figure on page 9) is divided into seven levels, from the spray/splash zone
to the greatest depths. Each level is then divided according to substrate type
(mud, sand, rock, etc.) and, for each substrate, there are biocoenoses,
associations and facies, each of which, from a conservationist point of view,
may be considered as a single habitat. The habitats presented in this volume
are listed on pages 118-119; other habitats are represented by a number.
Next to the substrate or biocoenosis is the number of habitats allocated to
that category.
Astroides calycularis concretions
Lithophyllum lichenoides
117
118
Barcelona classification: short list of benthic habitats
I. SUPRALITTORAL
11 habitats
II. MESOLITTORAL
II. 1. MUDS
3 habitats
II. 2. SANDS
2 habitats
II. 3. STONES AND PEBBLES
2 habitats
II. 4. HARD BEDS AND ROCKS
II. 4. 1. Biocoenosis of upper mesolittoral rocks
5 habitats, of which:
II. 4. 1. 4. Association with Lithophyllum papillosum and Polysiphonia ssp.*
II. 4. 2. Biocoenosis of lower mesolittoral rocks
10 habitats, of which;
II. 4. 2. 1. Association with Lithophyllum byssoides [framework with L. tortuosum] *
II. 4. 2. 2. Association with Lithophyllum trochanter
II. 4. 2. 3. Association with Tenarea undulosa
II. 4. 2. 8. Concretions with Neogoniolithon brassica-florida *
II. 4. 2. 10. Pools and lagoons sometimes associated with vermetids (infralittoral enclave) *
II. 4. 3. Mesolittoral caves *
2 habitats, of which
II. 4. 3. 1. Association with Phymatolithon lenormandii and Hildenbrandia rubra *
III. INFRALITTORAL
III. 1. SANDY MUDS, SANDS, GRAVELS AND ROCKS
III. 1. 1. Euryhaline and eurythermal lagoon biocoenosis
12 habitats, of which:
III. 1. 1. 2. Facies with Ficopomatus (= Mercierella) enigmaticus
III. 2. FINE SANDS WITH MORE OR LESS MUD
13 habitats
III. 3. COARSE SANDS WITH MORE OR LESS MUD
2 habitats, of which:
III. 3. 1. Biocoenoses of coarse sand and fine gravel mixed by waves
III. 3. 1. 1. Rhodolith associations *
III. 3. 2. Biocoenoses of coarse sand and fine gravel influenced by bottom currents
(also found in circalittoral)
3 habitat, of which:
III. 3. 2. 1. Maërl facies (association with Lithothamnion corallioides and Phymatolithon
calcareum; also found as a facies of coastal debris) *
III. 3. 2. 2. Rhodolith associations *
III. 4. STONES AND PEBBLES
2 habitats
III. 5. POSIDONIA OCEANICA MEADOWS
5 habitats
III. 6. HARD BEDS AND ROCKS
III. 6. 1. Biocoenosis of infralittoral algae
36 habitats, of which:
III. 6. 1. 3. Vermetid facies *
III. 6. 1. 14. Facies with Cladocora caespitosa *
III. 6. 1. 31. Facies with Astroides calycularis
III. 6. 1. 35. Facies and associations of coralligenous biocoenoses (in enclave) *
Giulio Relini
IV. 2. 4. Biocoenosis of coarse sand and fine gravel influenced by bottom currents
(found in areas with particular hydrodynamic conditions, like straits;
also found in infralittoral)
1 habitat
IV. 3. HARD BEDS AND ROCKS
IV. 3. 1. Coralligenous biocoenoses *
16 habitats, of which:
IV. 3. 1. 1. Association with Cystoseira zosteroides *
IV. 3. 1. 2. Association with Cystoseira usneoides *
IV. 3. 1. 3. Association with Cystoseira dubia *
IV. 3. 1. 4. Association with Cystoseira corniculata *
IV. 3. 1. 5. Association with Sargassum spp. (local) *
IV. 3. 1. 6. Association with Mesophyllum lichenoides
IV. 3. 1. 7. Association with Lithophyllum frondosum and Halimeda tuna
IV. 3. 1. 8. Association with Laminaria ochroleuca *
IV. 3. 1. 9. Association with Rodriguezella strafforelloi *
IV. 3. 1. 10. Facies with Eunicella cavolinii *
IV. 3. 1. 11. Facies with Eunicella singularis *
IV. 3. 1. 12. Facies with Lophogorgia sarmentosa *
IV. 3. 1. 13. Facies with Paramuricea clavata *
IV. 3. 1. 14. Facies with Parazoanthus axinellae
IV. 3. 1. 15. Coralligenous platforms *
IV.3. 2. Semi-dark caves (also in enclaves in upper stages) *
4 habitats, of which:
IV. 3. 2. 2. Facies with Corallium rubrum *
IV. 3. 3. Biocoenosis of shelf-edge rock
1 habitat
V. BATHYAL
V. 1. MUDS
V. 2. SANDS
V. 3. HARD BEDS AND ROCKS
V. 3. 1.Biocoenosis of deepwater corals *
VI. ABYSSAL
VI. 1. MUDS
*: priority habitats
IV. CIRCALITTORAL
IV. 1. MUDS
IV. 2. SANDS
IV. 2. 1. Biocoenosis of muddy detritic seabeds
IV. 2. 2. Biocoenosis of coastal debris
IV. 2. 2. 1. Association with rhodoliths
IV. 2. 2. 2. Maërl facies (association with Lithothamnion corallioides and
Phymatholithon calcareum)
IV. 2. 2. 10. Facies with large branching bryozoans *
IV. 2. 3. Biocoenosis of coastal debris
4 habitats
2 habitats
11 habitats, of which:
3 habitats
5 habitats
1 habitat
2 habitats
Ficopomatus enigmaticus reefs
1 habitat
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120
In the Mediterranean, 161 habitats are classified, 61 of which are considered
extremely important and, as such, their protection is indispensable for the
maintenance of Mediterranean biodiversity. They were selected according to
five criteria: vulnerability, natural heritage value, rarity, aesthetic value, and
economic importance. According to their scores, these habitats were then
subdivided into three categories:
D - determinant (or P: priority habitat): requiring rigorous protection;
R - remarkable: deserving special attention and management;
NR - not important.
As regards the habitats described in this volume, 29 out of the 36 listed are
priority habitats, i.e., almost half of the 60 priority habitats of the SPA/BIO in
Italy. This emphasises the importance of these environments for Mediterranean
biodiversity, and the gravity of the fact that they were not included in the
Habitats Directive.
In order to enhance protective measures and cooperation measures between
the signatories to the Barcelona Convention, Action Plans (AP) were devised.
One of these concerns vegetation, and mentions bioconstructions built by
calcareous algae; another devoted to coralligenous systems and other
calcareous concretions has recently been approved.
One of the aspects worthy of consideration is the subject matter of this Action
Plan: although it mentions calcareous bioconcretions, it focuses on
Biogenic construction
coralligenous populations and rhodolith
beds. Bathyal (deep) populations of
white corals and the shallower
assemblages of Dendropoma petraeum
and Lithophyllum byssoides are not
included because, according to the
AP, they belong to environments
which are completely different from
those of coralligenous systems, with
Sample of rhodoliths collected with a dredging
different species, dynamics and stress
grab
factors.
In any case, the trottoirs (reefs) are already included in the AP for the
conservation of marine vegetation. The same may be said for the deepwater
species Cystoseira, although they are sometimes characteristic of
coralligenous facies.
According to the AP for the protection of Mediterranean coralligenous
assemblages and other calcareous bioconcretions, the coralligenous domain
is a typical Mediterranean seascape, which includes coralline algae that
accrete in dim light and relatively calm water. The rhodolith beds are
considered sedimentary seabeds covered with free calcareous algae (coralline
algae or Peyssonneliaceae), which also live in poorly lit environments.
Within the framework of the AP to protect the Mediterranean coralligenous and
other calcareous bioconcretions are six strategies:
- evaluation of the current state of coralligenous populations;
- collection of data and drawing up of inventories;
- monitoring;
- research;
- conservation;
- the need to identify guidelines to assess the environmental impact on
coralligenous and maërl systems.
The AP describes specific criteria for identifying sites of particular environmental
importance, emphasising that:
● they should be highly representative of a large geographical area;
● there should be sufficient information available to monitor and manage them;
● they must be healthy (in order to become reference sites) or, if disturbed by
man’s activities, such activities should be clearly identified, so that information
needed to assess their impact can be gathered.
The importance of monitoring has been emphasised by the great numbers of
die-offs that have occurred in recent years, highlighting the fact that data are
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122
needed to understand the dynamics of generally very stable communities,
which must therefore be analysed according to suitable time-scales. In
addition, only by monitoring can experts evaluate the success, or otherwise, of
specific conservation measures.
As regards research, the AP identifies some taxonomic groups (essentially
small vagile species) which require particular attention in the near future, and
suggests two main types of action: study of long-term evolution (the
coralligenous domain can only be analysed over long periods) and its
functioning. The importance of the latter is clearly associated with the need to
examine the growth, demographic models, vulnerability to disturbance and
resilience of the builders of coralligenous assemblages or rhodolith beds, in
order to plan and provide for specific conservation measures.
Conservation measures are briefly described in point 5 of the AP, according to
the main categories of threat to Mediterranean biodiversity identified in the
Strategic Action Programme for the Conservation of Biological Diversity in the
Mediterranean (SAP/BIO). The main threats are: trawl fishing, small-scale/noncommercial and recreational fishing, methods of anchoring, introduction of
alien species, global warming, discharge of wastewaters, and aquaculture. The
AP also expresses the hope that specific laws and regulations will be
implemented to ensure legal protection to coralligenous assemblages and
rhodolith beds, similar to those which the European Union has already provided
Sponges on a coralligenous concretion
for Posidonia oceanica meadows. As
regards the guidelines proposed to
assess the environmental impact on
coralligenous systems and maërl, the
AP states that protected marine areas
should be created specifically to
preserve these assemblages, as
several nations have already done for
P. oceanica. This AP is only a part of a
A model of the kind of destructive trawl used by
wider Action Plan for the Conservation
boats to collect red coral
of Marine Vegetation, although the
latter focuses on assemblages composed of plant species. The AP includes
animals, and views national and regional priorities as being equal.
In the wake of laws drawn up for the conservation of Neptune grass meadows,
several international initiatives now aim at providing legal protection to the
coralligenous domain and rhodolith beds. At EU level, the Habitats Directive
proposes the creation of Sites of Community Importance (SCI), according to
the presence of habitats and species indicated in its Annexes I and II. It is
important to note that these Annexes contain lists of priority habitats and
species - ones which risk becoming extinct in the territories in which the
Directive applies and for whose conservation both the EU and its member
states accept responsibility.
The list of habitats to be protected is insufficient for the Mediterranean, as only
Posidonia meadows, coastal lagoons, and submerged and semi-submerged
caves have been included. However, in recent years, the “Marine Rocks”
habitat of Directive 92/43/CEE has been considered, at Mediterranean level, as
including benthic hard substrate assemblages deserving particular protection
and subject to initiatives, like the Barcelona Convention, issued within the
international framework to preserve biodiversity.
In addition to the above-mentioned measures for the legal protection of
coralligenous assemblages and rhodolith beds, Marine Protected Areas
(MPA) are also very efficient for safeguarding particularly important sites, as
emphasised by the AP for protecting coralligenous and other Mediterranean
calcareous bioconcretions.
These habitats are listed in many of the 25 Marine Protected Areas established
in Italy as of June 2008. Five of them (Portofino, Miramare, Plemmirio, Torre
Guaceto and Tavolara) have been identified as Specially Protected Areas of
Mediterranean Importance (SPAMI) due to their important status as
biodiversity heritage.
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124
■ Causes of degradation and destruction of organogenic formations
Several causes directly or indirectly associated with human activities
contribute to the disturbance, degradation and even destruction of
coralligenous and other organogenic formations. These causes may have
effects on a large scale, like global warming, or locally, like small polluting
discharges. Obviously, effects depend on several factors, and vary according
to the type of bioconcretion and its vulnerability, sensitivity, poor resistance
(inability to change despite stress) and low resilience (capacity measured as
the time required to return to the same conditions as before the onset of
stress).
Unfortunately, the scientific literature on the effect of negative impacts on
organogenic formations is limited, when compared with that on marine
phanerogams. Moreover, there are practically no detailed maps of these areas,
and mapping is essential in order to monitor possible changes in coralligenous
and other bioconcretions over time. Many of the changes which have occurred
in recent years are documented by underwater photography.
Climatic changes. In recent decades, periodic die-offs of filter-feeding
organisms have been recorded in the north-western Mediterranean, at depths
between 10 and 40 metres, especially in coralligenous environments. The
An area left bare by the illegal collection of date mussels
phenomenon has been analysed in
Liguria, the Balearic Islands, along the
coast east of Marseilles, and in the Gulf
of Naples.
The most plausible explanation for
these massive mortality events, which
occurred in summer months over
hundreds of square kilometres and
killed many sea fans - among the most
representative organisms of the
coralligenous communities at depths
of over 40 metres - is an anomalous rise
Benthic mucilage on Eunicella cavolinii
in the temperature of surface waters
and shifting of the thermocline to
greater depths.
These modifications in turn were probably caused by global climatic
changes. In summer, the Mediterranean is affected by marked thermal
stratification, resulting in warm surface waters which, in the Ligurian Sea,
may reach 25-26°C. The temperature slowly decreases along the water
column down to the thermocline, a layer in which temperature declines by at
least 1°C for every metre of depth. However, a slight increase in thermocline
depth causes a considerable fall in temperature (up to 10°C). All organisms
which do not tolerate warm water move to areas below the thermocline, and
when that too sinks to abnormally low depths, they undergo stress, which
results in their death if it lasts too long. This situation is made more severe by
the fact that, in summer, there is less food available, and filter-feeders do not
have sufficient food reserves. Nonetheless, the true cause of the mass
mortality of various species is not yet fully understood. Some scientists think
that physiological stress (high temperature and lack of food) weakens
organisms, allowing the development of pathogens which would be
quiescent in normal conditions.
In recent years, these episodes of mass mortality have affected various taxa,
the most frequently analysed being coelenterates (sea fans and red coral in
particular), as well as large sponges. Red coral living above 30 metres has been
severely affected, as were colonies of the large red sea fan Paramuricea
clavata, which died in many areas of the north-western Mediterranean at
depths above 40 metres. The situation was worsened by the summer
development of mucilage (algal blooms) which greatly increases the already
severe thermal stress.
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126
Expansion of maritime structures, dumping and suspended matter. Coasts
are increasingly affected by human activities - particularly with the construction
of marinas for yachts and other leisure vessels, discharge of wastewaters,
beach nourishment, and the building of embankments to create additional
beach space - resulting in direct and indirect degradation of organogenic
formations. The building of dykes, embankments, piers and quays cover and
destroy reefs of calcareous coralline algae, vermetids and even shallow
formations like those with Cladocora, which die immediately.
There are also indirect effects, such as changes in currents and wave dynamics,
water quality and, in particular, turbidity. New marine construction techniques
allow water to flow more easily inside ports and therefore give rise to better
environmental conditions.
Experience teaches us that much of the damage caused by constructions is
associated with the actual period of building and, more specifically, with the
techniques adopted. Port authorities should therefore focus on improving them.
During periods of construction, particularly when beaches are nourished, the
water becomes more turbid, often because the materials used are not suitable
and contain high percentages of silt. The direct and indirect consequences are
very harmful, and lead to reduced irradiance and the deposition of sediments on
top of living organisms. In the “worst-case scenario”, the seabed becomes
muddy, and bank biocoenoses die.
Cladocora caespitosa formation
Discharge of pollutants, eutrophication and aquaculture. Discharges from
industry, cities or shipping cause direct and indirect damage to coralligenous
and other bioconcretions by modifying the chemico-physical characteristics of
the water column and introducing pollutants or even simply nutrients. The latter
increase eutrophication, producing well-known negative consequences to
biotic communities. The growing use of floating cages for fish-farming along
Mediterranean coasts is another threat to benthic biocoenoses. Great
quantities of nitrogen and phosphorus are introduced into the water and, if
dispersion by water movement is insufficient, eutrophication may be severe. In
addition, food for farmed animals and other products used (such as drugs for
veterinary use, anti-fouling agents, etc.) contain various xenobiotic and toxic
substances. Discharges from ships also have deleterious effects, especially if
the areas in question are crowded with tourists. Water from many rivers have
recently been found to contain high percentages of sex hormones - deriving
from the use of contraceptive pills - which have damaging effects on the
reproductive cycles of many marine organisms. Lastly, many large Italian rivers,
like the Po, contain high concentrations of prohibited drugs, especially cocaine,
the effects of which must still be assessed.
Muddying and turbidity of water may also be caused by outflows from rivers
and streams, especially after heavy rain in their catchment basins. Run-off from
cultivated fields brings to the sea various pollutants contained in fertilisers and
pesticides. Large amounts of solid rubbish litter the seabed, particularly along
routes travelled by leisure craft and commercial shipping: in the latter case,
even bathyal seabeds may be affected.
Pollution by hydrocarbons is particularly damaging to organisms living in the
tidal zone, because these substances float for a certain period and, as the
water moves, are distributed on living organisms. Hydrocarbon films are
sometimes so thick and extensive that they obstruct the natural exchanges
between the environment and organisms, causing their death.
Pollution by wastewaters substantially reduces species richness: bryozoans,
crustaceans and echinoderms are more affected than molluscs and polychaetes.
For example, highly tolerant populations develop in large numbers, whereas
some taxonomic groups are completely wiped out. Biomass and the numbers of
individuals, especially large members of the epifauna, are also reduced, and the
construction of coralligenous assemblages comes to a halt, as it is replaced
by increased numbers of biodestroyers. Orthophosphate ions can hinder
calcification and, as pollution increases, one coralline alga with a large thallus,
Mesophyllum alternans, to give a single example, is replaced by members of the
Peyssonneliaceae family, which have a lower capacity for construction.
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128
Mechanical destruction, anchoring
sites, explosions, excavations and
scuba-diving. Several of man’s
activities contribute to the mechanical
destruction of coralligenous and other
bioformations. Excluding for the
moment fishing gear, improper
anchoring may be said to be one of the
main causes of biocenosis degradation,
Fishing nets on coralline algae
because the numbers of both leisure
craft and visitors to areas of great
natural importance, especially offshore banks, have greatly increased - and not
only in summer. Obviously, the damage caused by the anchors of many types
of ships, ranging from large cruise liners to military and cargo vessels, is even
greater when they fall on Posidonia oceanica meadows and coralligenous
formations. Anchoring in these areas should of course be banned immediately
but, before this can be done, areas with sensitive biocoenoses must be
properly mapped on all nautical charts.
The excavations necessary for laying cables and pipelines for all kinds of essential
supplies such as water, oil, gas and electricity, and the transport and disposal of
wastewaters, completely destroy coralligenous formations along their entire
length and for a greater width than the cables and pipelines themselves. When
feasible, these operations should be carried out along routes planned to avoid
coralligenous formations and, once again, maps clearly marking the locations of
benthic biocoenoses are required. Severe damage is also caused by explosives,
although, fortunately, their use for illegal fishing has recently been greatly reduced.
Another form of destruction is caused by aquarium lovers who break pieces off
concretions or even living organisms such as sea fans as souvenirs, or to stock
their aquariums. These delicate organisms only survive for a short time and so
new pieces, which in Liguria are called “grotto rocks” or “living rocks”, are again
taken from the sea. This is clearly illegal, and must be forbidden.
Tourists and scuba-divers can also cause the mechanical destruction of
biocoenoses. Bathers walking on vermetid or coralline algae reefs may damage
the most delicate parts of these formations just by treading on them. Abrasions
caused by divers reduce the development and size of erect species, which are
leafy and branched, and favour the growth of encrusting or massive forms. For
instance, research has shown that, in an area where diving is forbidden, colonies of
the large, fragile bryozoan Pentapora fascialis grow at all exposures, whereas in a
nearby area, where diving is allowed, they only grow in the most sheltered spots.
Fishing. Fishing is undoubtedly the human activity which, if carried out
improperly, is particularly damaging to coralligenous formations. Illegal trawling
in particular is the worst type, because it mechanically and directly destroys
coralligenous bioconcretions and rhodolith beds, and at the same time
increases water turbidity (see above), and also contributes to the dispersion of
alien species like Caulerpa taxifolia and C. racemosa (see p. 133).
In Italy, as is well-known, trawling is carried out with a conical sack-shaped net,
with an entrance kept open at the sides by two gates (otter boards) and vertical
by flotation (a float-line in the upper part) and a series of weights on the lower
edge (footrope), to keep the net dragging along the seabed, or even allowing it to
sink slightly into the bottom sediment. Two trawl gates are connected to the boat
with steel cables (12-18 mm in diameter) of varying lengths, according to the
depth of the seabed on which the net is used (if carried out correctly, the cables
should never touch the bottom). As well as the trawl net, the parts causing the
most damage are the footrope and particularly the otter boards, which may
weigh 100 kg each and are dragged along at a speed of 1-2 knots. It is not
difficult to imagine the catastrophic consequences of their passage to all marine
communities - coralligenous formations, rhodolith beds, bryozoans, Cladocora,
flatfish species, and white corals. Trawling is particularly harmful to white corals,
because fishermen tow the gear close to the coral banks, despite the risk they
run of having their equipment entangled or trapped in the concretions.
The use of otter boards in trawl fishing caused great damage to bioconcretions
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130
White seabream (Diplodus sargus sargus)
In the European Union and in Italy, trawling is illegal at depths of less than 50
metres and within three miles of the coast. Large chains and wheels inserted at
the mouth of the net are also illegal, and net meshes must be at least 40 mm.
However, these restrictions are often not respected.
Dredges and the so-called “rapido”, all heavy metal structures, are used
especially in the northern Adriatic to take up molluscs and benthic fish like
flatfishes and gobies. They have devastating effects on organogenic formations
living on beachrock and the tegnùe, around and over which the nets are
trawled, despite the definite risk of losing the equipment.
Although bottom long-lines cause different and lesser damage, they are still
harmful because they are used in areas where trawling and fishing with towed
gear are not or cannot be carried out. Bottom long-lines have lines and hooks,
which can become entangled in seabed organisms and damage the
bioconcretions of white corals and bryozoans of coralligenous formations by
breaking pieces off them. Even worse, this type of fishing gear is also used for
recreational fishing, which generally uses hand-lines with hooks and rods.
When hooks, plummets or nylon lines are trapped in sea fans or other benthic
organisms and the fisherman pulls on the line, either the nylon line breaks or, if
it does come loose, it partially or completely destroys the organism in which it
has become caught. Fishing-lines lost on the seabed get twisted into tangles of
nylon that may damage and even kill benthic organisms. Scuba-divers often
see lengths of fishing-line, together with their plummets and hooks, enmeshed
in dying organisms.
All fishing gear which comes into contact with the seabed can be harmful. There
are also creels and gill nets, and trammels in particular, especially when they are
weighted with lead to allow them to sink to the bottom quickly, as is done to
catch spiny lobster. For full understanding of the negative effects of such
equipment, it is enough to watch fishermen as they clean the nets they have
used on coralligenous formations, rhodolith beds, and other assemblages. They
remove and throw back into the sea pieces of calcareous concretions, sea fans,
bryozoans, seaweeds, and various non-sessile organisms like gastropods,
bivalves, crabs, echinoderms, etc., all of which, if collected in time, could at
least have been used for laboratory work or teaching.
In addition to devastating effects on erect benthic species, intensive fishing
also reduces the numbers of fish species like dusky grouper (Epinephelus
marginatus), white and sharpsnout seabream (Diplodus sargus, D. puntazzo)
and common dentex (Dentex dentex).
Recreational fishing, sometimes even more than professional fishing, now also
plays an important role in depleting these species and altering population
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132
dynamics. This is because large, and therefore adults, specimens are caught
and, in species in which mature male and female individuals differ in size, their
sex ratio is changed, as has occurred in the case of the dusky grouper: large
specimens are only male, because this is a protogynous hermaphroditic
species. Female dusky groupers reach maturity when they attain a length of 40
centimetres, but males only mature when they are at least 80 centimetres long.
Spearfishing scuba-divers are considered the main agents responsible for the
impoverishment of the above-mentioned species, because they do not abide by
the rules, according to which fishing must only be carried out while free-diving,
and the daily catch must not exceed a specific weight. The particularly negative
effects of spearfishing on some species are easily demonstrated by the rapidity
with which depleted populations manage to increase in the Italian Marine
Protected Areas, where this is the only type of fishing which is forbidden,
independently of the level of protection of the zone in question.
In the tidal area, vermetid and/or coralline reefs may be damaged by being
trodden on, or by other mechanical action by people collecting limpets and other
molluscs. Many Lithophyllum lichenoides formations have been completely
destroyed by people trampling on them or anchoring small boats on them.
Other extremely destructive types of fishing equipment are the so-called St
Andrew’s Cross and the “ingegno”, fishing implements invented in the Middle
Ages for dredging up red coral (see pages 68 and 123).
Common dentex (Dentex dentex)
Invasive alien species. Thirty-five of
the 170 artificially introduced species
known to live in Italian seas are
macrophytes, and only a few algal
species have been found in
coralligenous assemblages. At least
three of them are highly invasive.
The best-known is the green alga
Caulerpa taxifolia, mistakenly called killer
alga, and the subject of debate among
researchers. It has colonised extensive
areas of Italian seabeds, causing
concern due to its fast expansion,
because it does not reproduce sexually
in the Mediterranean. Along some areas
of the Franch and Italian coastlines, it
has massively invaded coralligenous
Caulerpa racemosa var. cylindracea
formations. The development of the
other alien Caulerpa species, C. racemosa var. cylindracea, is also worrying,
as its expansion has reached a larger scale than that of C. taxifolia, and the
damage it causes to coralligenous assemblages is now evident.
However, the most dangerous species for these environments is the small red
alga Womersleyella (Polysiphonia) setacea, which is now found all over the
Mediterranean and in coralligenous banks, where it forms tufts 1-2 centimetres
thick which cover coralligenous organisms and concreting seaweeds in
particular (Mesophyllum alternans, Lithophyllum cabiochae and others),
jeopardising their metabolism. The filamentous tufts of this alien reduce
irradiance, hindering the photosynthesis and growth of coralline algae. In
addition, its webs of filaments traps sediments, which cover coralligenous
organisms even further, thus preventing other seaweeds from settling; in
particular, it also hinders colonisation by calcareous algae and animals living in
the coralligenous domain. As this process has long-lasting effects, the damage
caused to coralligenous communities is considerable. Probably only a
voracious herbivore could control Womersleyella’s harmful tufts.
Coralligenous assemblages host three other non-indigenous seaweeds, which
may develop with or without Womersleyella. One is Acrothamnion preissii
which, although it has colonised deep-water areas, has still not caused any
great harm. It has been found on rhodolith beds and platform coralligenous
formations in the Tuscan archipelago.
133
■ Geographical distribution
134
The distribution of Mediterranean
bioconcretions is still poorly known, as
there are areas which have recently
been studied quite thoroughly, and
others about which we know very little
(although the same may be said of
many Mediterranean biocoenoses).
As regards the Adriatic Sea, research
has been carried out on the coasts of
former Yugoslavia and some of the
more southerly islands. More work
has been done on the Adriatic
coralligenous formations lying between
the promotory of the Conero (nearly
half-way down the Italian “boot”) and
Coralligenous formation off the island of Elba
(Tuscany)
the coastline off Bari and the Salento
peninsula (the “heel” of the boot).
Several works have concentrated on the coasts of Sicily, the Aeolian, Pelagic
and Egadi archipelagos and the island of Ustica. Further north, the coasts of
Calabria and Basilicata are little known, whereas those of Capo Palinuro, the
Gulf of Naples and the islands of Capri and Ischia, especially as regards
coralligenous assemblages in semi-dark caves, have been more carefully
examined. The flora and red coral along the coasts of Tuscany and its
archipelago have been quite well studied. In Liguria, research has greatly
contributed to the knowledge of bryozoan, coelenterate and sponge populations
in the Gulf of La Spezia, the promontory of Portofino and other Ligurian areas.
As regards the Mediterranean Sea in general, the coralligenous formations off
Marseilles and its islands, the Marine Park of Port Cros and some areas of
Corsica are well-known. Spanish scientists have thoroughly examined the
Catalan coasts, the Medas and Balearic Islands and the Alboran Sea, near
Gibraltar. The research carried out at various times in the area near Banyulssur-Mer (Eastern Pyrenees) has been fundamental.
Sea fans
Commercial importance. All biogenic constructions, and coralligenous
formations in particular, play an important role in biodiversity although, at
present, it is difficult to assess just how valuable they are in commercial terms,
the only exception being red coral.
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136
Field survey methods and mapping
Short surveys of large coralligenous
banks are sometimes necessary, in order
to assess damage caused by sea storms
or human activities, to establish suitable
boundaries for future marine parks, or to
carry out preliminary analyses to select
areas for long-term monitoring. Such
field surveys are carried out by indirect
methods like aerial photography and
satellite mapping (described later) or
by direct methods like those discussed
below.
Manta tows. The “manta tow” technique
is used to monitor large-scale changes in
reef covers caused by storms, coral
bleaching and attacks by Acanthaster
planci, the corallivorous crown-of-thorns
starfish. Although there are no real
standard methods, a snorkel diver is
generally towed above the reefs behind a
boat travelling at a constant speed. The
snorkeller holds on to a “manta board”
measuring 40 x 60 cm, and during short
Quadrats, used for counting individuals
tows (generally each lasting a couple of
minutes) makes a visual assessment of
specific variables - usually the
percentage of substrate cover - and,
when the boat stops, records details on
a data-sheet attached to the manta
board. Normally used in tropical waters,
this method has also been used in the
Mediterranean to identify areas for future
detailed study, or to pin-point shoals and
areas of the seabed to be analysed later
by divers. Underwater scooters have
also been used.
Quadrats. Quadrats are used for all
types of ecological sampling, and many
approaches are applied. Quadrat
sampling is carried out by placing a
square frame on the substrate and
recording the number of sessile
organisms found within it.
Quadrats are used to count individuals
(density per m2), to gauge the average
substrate cover, and to assess the
Francesco Cinelli
frequency of individuals, and their
presence or absence.
Visual assessments of cover percentages
are commonly used in marine
environments, although several studies
have shown that they should always
be performed by the same person.
This is because estimates may vary
from person to person, as an element
of subjectivity is easily introduced, and
operator error may lead to less accurate
results. Compared with other techniques
of quantitative sampling, quadrats have
the advantage that data are collected
cheaply and quite rapidly in the field,
and this is very important when working
at considerable depths.
One disadvantage is that sampling is
difficult on sloping, uneven substrates.
Photo-quadrats. With this survey
technique, a quadrat is photographed
for later analysis. This method can also
be used to obtain photos of the same
area over time, in which case cameras
for time-series photography are
mounted on fixed stations. Although this
is a good method for monitoring benthic
communities living on hard substrates
and provides accurate information
on covers, analysis of the resulting
photographs is time-consuming.
Photo-quadrats have the advantages of
being non-destructive and quick, and
they provide much information, but their
disadvantages include possible technical
problems, less good taxonomic
identification, and the great difficulty
of analysing camouflaged populations.
Transects. Transects are used to reveal
linear patterns along which communities
of organisms change. A transect line is
laid along the area to be analysed: in
case of marine benthos, it is a nylon
rope marked and numbered at 1-metre
intervals laid on the seabed. Analyses
can be carried out either by recording
the organisms present at each marked
point, or by counting the organisms
touching the line along its whole length.
Transects perpendicular to the coastline
(depth transects) maximise
environmental variability and are suitable
for bionomic analyses aimed at
describing population zonation;
transects parallel to the coastline (at
constant depth) minimise environmental
variability and are used to study the
qualitative and quantitative composition
of specific populations.
The advantages of the transect method
are its low cost and rapidity of
execution. Among its disadvantages
when used on coralligenous formations
is that it tends to underestimate cover
percentages in heterogeneous areas
with few organisms.
Video-transects. Underwater videorecordings enable scientists to examine
large areas quickly: modern underwater
video-recorders are light-weight and
compact, and can also be used by
operators with little experience.
A waterproof video-camera is mounted
on a support, for easier use and to keep
the focus perpendicular to the substrate.
The video-camera is pointed at the
substrate at a distance of 1-1.5 metres.
Both operator and camera are towed
along a 30-metre line by a boat
travelling slowly, at a speed of about
1 metre/second. Data are analysed by
Video Point Sampling (VIPS), allowing
the operator to “freeze” the footage at
regular or random intervals and to
overlay stills with an array of points,
to quantify the number of points
intersecting with various species within
the image.
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138
Field survey methods and mapping
Direct visual assessment. This method
is certainly efficient and enables divers
to produce very detailed maps
(on scales of 1:2000 or higher). It is
recommended for small areas, and is
also used as a supporting method when
large areas are analysed by other
techniques such as aerial photography
and echography, as it exploits results
from what some call “ID diving”: divers
analyse an area along transects placed
at regular intervals. Direct visual
assessment is certainly the most precise
method, not only because species are
identified in situ, but also because the
divers can see even the smallest clusters
of organogenic formations, and their
position is estimated with a margin of
error of only one metre. Mini-submarines
are also widely used.
Direct methods include those applying
optical instruments like Remote Operated
Underwater Vehicles (ROVs), which are
ROVs
Francesco Cinelli
tethered underwater robots equipped
with video-cameras, lights, sensors
to measure depth, temperature and
distance from the bottom, a compass,
and sometimes sonar equipment. ROVs
are operated by experts aboard a vessel,
on which a monitor shows the footage
and records its position. This system
may replace divers when work is done
at great depths; it is currently being
used in Sardinia to locate red coral.
Indirect methods include echographic
and acoustic surveys, and aerial and
satellite systems have also been used
to study the upper limits of Posidonia
oceanica meadows and other
seagrasses. They may also be used
to analyse superficial organogenic
concretions like vermetid and
Lithophyllum lichenoides reefs.
Echographic surveys. These use
high- or low-frequency sounding lines:
the former are commonly used and
provide unidimensional maps of the
seabed. Low-frequency echography
uses frequencies of 2.5 KHz.
Acoustic surveys. These employ sidescan sonar equipment of the type
normally used in acoustic physiography,
defined as a technique that replaces
light with sound. Acoustic sources
”illuminate” the seabed obliquely with
impulses that are reflected back to the
sonar in various ways, according to
what they strike.
Conventional aerial photography. If sea
conditions are good, aerial photographs
enable benthic biocoenoses to be
mapped quickly and accurately. Data are
collected to draw up precise maps
monitoring the evolution of the superficial
areas of biocoenoses, although problems
of photo-interpretation cannot be
completely eliminated.
Airborne Remote Sensing (ARS).
Mapping of benthic populations in
shallow, sufficiently transparent waters
can be performed by remote sensors
and/or analog or digital cameras carried
by aircraft. If only the most superficial
concretions need to be examined, colour
photographs taken at a distance of
2-4 metres are generally sufficient. The
photographs must then be processed by
algorithm-based numerical scanning, to
highlight the upper limit to be digitised.
Geographic Information Systems (GIS).
The growing expansion of human
populations and the consequent increase
in human pressure on natural systems
require technologically advanced means
to preserve these natural habitats.
However, biology and mathematics alone
cannot always collect and analyse
changes, and even IT (computer
technology) is not capable of solving all
the problems involved. An integrated
Divers carrying out transect sampling
system is required, like the Geographic
Information System. The GIS can not only
integrate data from various sources for
capturing, managing, analysing and
displaying all forms of geo-referenced
information. It is also a combined
system of integrated theories, scientific
procedures and IT can process very
different types of information into more
manageable forms. GIS technology
provides adequate solutions by
integrating theoretical approaches taken
from such far-ranging fields as geography
and ecology by means of a powerful
database with statistical functions. Just as
Newton’s law enabled classic mechanical
physics to become more predictable,
the GIS will in all probability be the
breakthrough allowing ecological sciences
to become more predictable, rigorous and
directly integrated in all decisions taken
at political and social levels, for proper
management of natural resources.
139
140
■ Proposals for management and protective measures
The extraordinary importance of ecosystems requires adequate monitoring
systems to be devised for their conservation and protection. First, we must
bear in mind that our real knowledge of these environments in general is still
scanty, and that there is a great gap in our knowledge of existing situations
between the western and eastern basins of the Mediterranean. It is difficult to
suggest specific monitoring and control techniques apart from those already in
place in Marine Protected Areas for Posidonia oceanica meadows and other
important biocoenoses. The threats to these particular types of underwater
heritage have been clearly identified, and it is therefore relatively easy to devise
monitoring plans to preserve them. Necessary measures include:
1. near coralligenous formations, bans on discharges of wastewater from
purification systems, since they increase concentrations of nutrients, modify
water turbidity, and cause desalinisation of water;
2. bans on fishing with destructive methods such as trawling, both on
coralligenous formations and nearby. In addition to direct mechanical damage,
indirect damage is caused by fine sediments which are resuspended in the
water column. These give rise to secondary damage caused by increased water
turbidity and clogging of the filtering systems of many active and passive filterfeeders. In some areas of the Mediterranean, systems of passive protection have
been put in place, such as artificial reefs to prevent the passage of trawl-nets;
3. bans on the use of gill nets near coralligenous formations. Gill nets drift with
currents, may become trapped in bioconcretions and cannot be retrieved,
causing severe damage which is directly proportional to the length of time they
are left on the concretions. There have been several cases of divers having to
free coralligenous reefs from these types of “shrouds”;
4. avoidance of beach nourishment near coralligenous formations, as well as
any type of maritime construction work (marinas, quays, embankments, piers,
terminals for regasification of liquefied natural gas, etc.);
5. bans on small-scale coastal fishing and recreational fishing aimed at
catching species of naturalistic importance or ones whose stocks have been
so depleted that they are now difficult to catch;
6. bans on indiscriminate diving without due care and attention to the rules now
adopted in all Marine Protected Areas, and the collection of organisms, whether
alive or dead. Organisms should not be disturbed: divers should not touch them
with any part of their bodies or equipment, nor should they cling on to large
but delicate sessile organisms like sea fans;
7. efforts to raise the awareness - not only of divers and students but also of the
general public - of the importance of preserving this huge natural heritage;
8. establishment of clearly defined rules for the introduction and marketing
of alien species.
Underwater fishing
Fishing nets trapped in bioconcretions
141
Teaching suggestions
GUIDO BRESSAN · GIUSEPPE GIACCONE · GIULIO RELINI
■ Brief introduction
● Objectives: to learn how organogenic
formations can be built by epibiosis,
stratification, gregariousness, fusion,
and colonialism; to learn about
bioconstructors, biodestroyers, filterfeeders, detrivores and other habitatbuilders; to learn about carbon fixation
The white coral Madrepora oculta, with the
and how carbon dioxide passes from
annelid Eunice norvegica (detail)
the atmosphere and is dissolved in
seawater affecting its concentration of
carbon dioxide and influencing climate change; to learn about the mineralisation
of the cell walls in plants and/or exoskeletons in animals; of the death,
fragmentation and/or burial and fossilisation of more or less complete
calcareous remains; to learn about biogenically constructed seascapes, with
positive consequences on habitats and species diversity. General presentation
of monumental biogenic reefs in the Mediterranean: superficial calcareous
platforms with encrusting red seaweeds and vermetid reefs; the orange
formations of the madrepore Astroides calycularis and the imposing banks of
the zooxanthellate coral Cladocora caespitosa; deepwater formation of
complex and varied coralligenous biocoenoses, rhodolith beds, facies with sea
fans and bryozoans, and large banks of white coral.
Before speaking of marine biogenic constructions, it is advisable to introduce
the subject more generally, by describing the capacity of some living organisms
for modifying and even building their own habitats in order to make them more
hospitable and suitable for colonisation by their own species and to contribute,
with other species, to the formation of living communities, i.e., biocoenoses, to
maximise the shared use of energy resources of the chemico-physical
environment and the food-chains of biological components.
In a similar fashion, man builds cities and transforms the countryside for
agriculture, livestock rearing, industry and transportation. All constructions,
Bryozoans and the sponge Clathrina coriacea
143
144
whether made by man or by other organisms, must take into account local
environmental factors, and modifiy them either to accommodate these
favourable characteristics or to withstand their demolishing power: there are
communities of organisms which may modify them to favour their own
sustainable development, just as they may modify them negatively and
therefore degrade them through unsustainable development and destruction.
Students should become aware of the fact that the limestone mountains and
hills and most of the territory they see today, were built by bioconstructing
marine organisms, either directly with their fossilised remains or indirectly with
the sediments eventually produced by those remains.
The relationship between terrestrial and marine landscapes should be
introduced, explaining how this is the result of a dynamic balance between its
components, starting from the initial situation (geology, mineralogy,
geomorphology), the various phases and durations of biogenic constructions,
the interference of geodynamic and climatic events, and the effects in time and
space of the actions of the organisms which use these reef-like structures.
All these themes have been examined in the previous sections, which provide
material for in-depth analysis, as well as graphic and photographic material
according to the type of lessons given to students.
● Levels: students of the fifth year of secondary school; students of the third
year of middle school and those of other secondary-school grades, with
Ficopomatus enigmaticus
simplified versions of these subjects
(how calcareous platforms are created
in shallow-water environments, how
carbonates are mineralised, and how
bioconcretions are fossilised in
calcareous formations of emerging land).
● Sites to visit and materials to collect:
rocky coasts with cliffs containing
platforms with coralline algae and
The mollusc Platydoris argo
vermetid molluscs, great care being
taken not to tread on the formations or
to collect samples, as this may damage
the formations and trigger instability
phenomena in them; harbours with
fishing boats where gill nets are
normally cleaned of the organogenic
concretions and building organisms
that get trapped inside. Fishermen can
be asked to set aside these remains and
those they gathered when pulling the
Eggs of Platydoris argo
nets aboard. The specimens can then
be fixed in alcohol or seawater with 4% formalin, and analysed under the
microscope in the laboratory. Other places to visit are aquariums and museums
of natural science, palaeontology, botany and marine sciences which exhibit
groups of biocontructing organisms or specimens of calcareous marine
organisms. Diving clubs can be asked to provide copies of photographs and
videos taken in bioconstructed marine environments and collected in CD or DVD.
● Equipment: bibliographic and other material are easily available. Charts can
be drawn up in class by students to illustrate red coralline seaweeds (see pages
147-149) and also the main species of builders of organogenic structures
(molluscs, polychaetes, bryozoans, anthozoans). Documentaries on Marine
Protected Areas (available from the Italian Ministry for the Environment) can be
shown in class, together with information from websites, like that of the
Department of Botany, University of Catania (www.unict.it), which was created
for habitats and seascapes with marine vegetation (log on to this same website,
to see herbarium sheets or plastic containers, scanned specimens of
calcareous coralline algae, etc.). The same calcareous seaweeds are also found
in the website of the Herbarium of the Department of Biology, University of
Trieste (http://dbiodbs.univ.trieste.it).
145
146
During excursions to harbours, fishermen’s landing-stages and/or other points
along the coast, students should carry strong, transparent plastic bags or
boxes with well-fitting lids in which to place specimens of animals and other
still living material found in fishing-nets or along beaches, together with such
useful equipment as magnifying-glasses, tweezers, etc., and digital cameras
for photographing coralligenous platforms, vermetid reefs, and other objects
of interest. Delicate specimens must be handled with great care. All
specimens must be labelled immediately with information regarding
provisional identification of species, point of collection, and the date (and
perhaps extra information regarding weather conditions, particularly after
storms). On returning to the laboratory, students should ensure that they have
enough containers of various sizes in which to preserve calcareous algae and
animals with exoskeletons, after they have been dried in the open air. For a few
weeks, decomposing specimens will smell foul and should be kept outside,
away from busy areas. Later work in the laboratory will involve optical
microscopy.
● Collaborations: collaborators could include staff from a Marine Protected
Area (if available), members of environmental associations connected with the
sea and its problems, divers, photographers and underwater documentary
experts, those working in the field of environmental education, and specialists
in marine biology and ecology.
Constructing calcareous algae
Guido Bressan
To provide additional practical material for learning about the vegetal
component of organogenic constructions, here are some descriptions regarding
calcareous algae - the builders of coralligenous formations - rhodolith beds,
shallow-water platforms and reefs:
a) suggestions regarding the details of individual species and their observation
under an incident light microscope;
b) suggestions for more general analyses, like watching documentaries and
videos on marine concretions.
a1) Examples of morpho-functional electiveness.
Lithophyllum stictaeforme has a leafy thallus and is
very elegant. Its laminar leafy structure is due to the
fact that hydrodynamics must guarantee the organism
a boundary layer, i.e., an optimal layer of water
covering it totally. If water movement is too strong,
the thallus grows without lamellae.
Mesophyllum lichenoides has a leafy thallus with
peripheral growth. It has darker pigmentation than
Lithophyllum stictaeforme and a greater number of
conceptacles (specialised cavities containing the
reproductive organs), shaped like warts, near the
centre of the lamellae, where the cells are more
mature. Pigmentation is paler towards the periphery,
where cells are younger and the margins are whitish,
due to incomplete calcification. The leafy shape
of the thallus is suited to the superficial metabolism
(anabolites vs catabolites) of the thallus.
Lithophyllum (=Titanoderma) trochanter has thalli
made up of small round pulvini which are attached to
the substrate at only a few points and are therefore
easily detached. It lives well when the pulvini become
attached to one another. This relatively rare, elegant
species is very beautiful and, as such, is collected
indiscriminately and risks extinction.
Its structure, made up of closely entwined branches,
favours the formation of structurally complex
interstitial micro-biocoenoses.
Lithophyllum (=Titanoderma) ramosissimus has round
pulvini similar to those of L. trochanter, composed
of entwined branches whose distal areas have
growth rings.
These very evident rings indicate successive, more or
less rapid, metabolic phases of development which,
however, cannot be dated. In these thalli, exfoliation
of the superficial layers (epithallic) is relatively common,
but can only be observed properly by scanning
electronic microscopy.
Halimeda tuna and sea fans
147
148
Constructing calcareous algae
Guido Bressan
Lithothamnion minervae. This rhodolith is composed of
several warty excrescences, sometimes irregularly
branched. Its wart-like conceptacles are at distal points
of the thallus in this species (and a few others), where
they form clusters and become prominent, for
better dispersal of their contents (spores or gametes)
for the propagation and perpetuation of the species.
Lithophyllum racemus has thalli covered with warty
nodules departing from a central area, shown here on a
detritic substrate. This rhodolith is often bubble-shaped:
the more spherical its shape, the more the energy of the
seabed makes it roll regularly. Its development, growth
and cellular differentiation in the part of the thallus that is
more exposed to light contribute to making it roll until
it finds a new barycentre.
Corallina elongata has a bushy, branched thallus made up
of stiff calcified units called intergenicula and uncalcified
nodes called genicula, not rigid, formed of oblong cells,
so that the thallus is jointed and can thus bend according
to water movements. Unlike encrusting red algae, which
are prostrate, species of Corallinales Articolatae are
always erect.
Rhodolith boxwork has a mineral nucleus, and its distal
parts are covered by at least two overlapping coralline
species. The laminae in the photograph are those of
Lithophyllum dentatum, which may live unattached in
environments with strong seabed energy, which ensure
that it rolls frequently.
Corallina elongata. The photograph shows live, uncalcified
thalli and mature conceptacles shaped like small
transparent urns revealing their content (spores?).
Uncalcified thalli are rare in nature, and are usually a sign
that the environment has been altered by the presence
of orthophosphates which restrict and even prevent
the calcification of cell walls. This phenomenon can be
reproduced in laboratory cultures.
Neogoniolithon brassica-florida is an epilithic species of
great ecological valence, which can enter the interstices
of other calcareous algae and/or animals (e.g., vermetid
molluscs of the genus Dendropoma, shown here) acting
as a cementing agent.
In the Mediterranean, this species aids to the formation
of banks in the mesolittoral. In tropical seas it contributes
to “cementing” coral reefs.
a2) Examples of mechanico-morphological adaptations
in calcareous red algae.
b) Subdivision into benthic levels.
Corallina officinalis is composed, like all the Articolatae,
by ramifiedl “articles”, shown here with reduced thalli
(they are generally slender and elegant). This mechanicomorphological adaptation allows the algae to withstand
the force of the waves in the biotopes where this species
normally lives.
Lithophyllum (=Titanoderma) trochanter is made up of
cylindrical excrescences, sometimes dichotomically
branched, which produce round, bushy pulvini.
The shape of this species clearly shows the direction
and intensity of the current: its excrescences may be
compressed and reduced (if subjected to water pressure,
like those shown on the left in this photograph) or
elongated, if they grow in a more sheltered position,
like the more pigmented parts towards the right.
A Lithophyllum byssoides reef. Note how the width of the
supralittoral, according to tidal level, guarantees
occasional splashing, sufficent, albeit not constant. by
waves. The width of this bionomic level, marked by the
presence-survival of endolithic Cyanophyceae,
corresponds to the vertical distance between the upper
limit, where the grey line stops, and the lower limit,
where the reef and mesolittoral begin.
There are many other examples of pigment distribution according to the light
electiveness of species (photophilic or sciaphilic), bathymetric distribution with
regard to flow, adaptations to light, vitality and colour heterogeneity. All these
factors lead us to consider biodiversity as not only structural but also functional, as
the various photosynthetic and accessory colours means that individual species
having a direct relationship with the number of populations in several environments,
heve many different ways of acquiring light energy. The more heterogeneous the
environment, the greater the possibility that all the components of the “radiating
flow” (sunlight), which would otherwise be dissipated, can be captured.
149
Select bibliography
BALLESTEROS E., 2006 - Mediterranean coralligenous assemblages: a synthesis of present knowledge.
Oceanography and Marine Biology: An Annual Review, 44:123-195.
Notes on the most recent knowledge of Mediterranean coralligenous assemblages.
BRESSAN G., BABBINI L., 2003 - Biodiversità marina delle coste italiane. Corallinales del Mar Mediterraneo:
guida alla determinazione (Marine biodiversity of Italian coasts. Mediterranean Corallinales: key-guide to
determination). Biologia Marina Mediterranea, 10 (suppl. 2): 1-237.
An excellent guide, with a rich colour plates for the identification of Mediterranean Corallinales algae. See
also http://www2.units.it/∼biologia/corallinales/index.htm.
BRESSAN G., BABBINI L., GHIRARDELLI L., BASSO D., 2001 - Bio-costruzione e bio-distruzione di Corallinales nel
Mar Mediterraneo (Bioconstruction and biodestruction by Corallinales algae in the Mediterranean Sea).
Biologia Marina Mediterranea, 8 (1): 131-174.
A compendium on knowledge of the various types of Corallinales bioconcretions and their destructive
processes.
CASELLATO S., STEFANON A., 2008 - Coralligenous habitats in the Northern Adriatic Sea: an overview. Marine
Ecology: An Evolutionary Perspective, 29 (3): 321-324.
A description of organogenic formations in the Northern Adriatic.
CHEMELLO R., DIELE T., ANTONIOLI F., 2000 - Il ruolo dei “reef” a molluschi vermetidi nella valutazione della
biodiversità in mare e cambiamenti globali (The role of vermetid reefs in assessing marine biodiversity and
global changes). Quaderni ICRAM, Rome: 105-118.
This paper emphasises how vermetid reefs, forming in the course of centuries, may be used not only to
describe great biodiversity but also climate changes.
CICOGNA F., CATTANEO-VIETTI R., 1994 - Il corallo rosso in Mediterraneo, arte, storia e scienza (Red coral in the
Mediterranean, its art, history and science). Ministero delle Risorse Agricole Alimentari e Forestali, Edizioni
Gutenberg, Sorrento: 263 pp.
CICOGNA F., BAVESTRELLO G., CATTANEO-VIETTI R., 1994 - Biologia e tutela del corallo rosso e di altri ottocoralli
del Mediterraneo (Biology and protection of Mediterranean red coral and other octocorals). Ministero delle
Risorse Agricole Alimentari e Forestali, Rome: 338 pp.
These two important volumes analyse various aspects associated with red coral, from the artistic to legal
spheres, from harvesting to science, ecology and biology.
COSTA F., COSTA M., SAMPIETRO L., TURANO F., 2002 - Enciclopedia illustrata degli invertebrati marini (Illustrated
Encyclopaedia of Marine Invertebrates). Arbitrio Editori, Scilla (RC): 239 pp.
A rich collection of colour photographs of the main marine invertebrates.
FURNARI G., GIACCONE G., CORMACI M., ALONGI G., SERIO D., 2003 - Biodiversità marina delle coste italiane:
catalogo di macrofitobenthos (Marine biodiversity along Italian coasts: a catalogue of macrophytobenthos).
Biologia Marina Mediterranea, 10 (1): 482 pp.
A list of Italian marine plant species with information about their distributions in various regions.
GAMBI M.C., DAPPIANO M. (eds.), 2003 - Manuale di metodologie di campionamento e studio del benthos
mediterraneo (Methods for sampling and analysing Mediterranean benthos). Biologia Marina Mediterranea,
Vol. 10 (Suppl.).
This manual, published in both Italian and English, describes the main methods used to analyse benthos,
i.e., organisms living on substrates. The chapters on hard substrates, macrophytobenthos, and monitoring
natural animal populations are particularly recommended.
GIACCONE G., 2007 - Il coralligeno come paesaggio marino sommerso: distribuzione sulle coste italiane.
(Coralligenous assemblages as submerged seascapes: their distribution along Italian coasts). Biologia
Marina Mediterranea, 14 (2): 124-141.
An analysis of coralligenous habitats as submerged seascapes in Italian seas.
GIACCONE G., DI MARTINO V., 2002 - Past, present and future of vegetational diversity and assemblages in the
Mediterranean Sea. 1st Mediterranean Symposium on Marine Vegetation. Ed. UNEP/RAC/SPA, Tunis: 34-59.
151
152
A volume in English describing phyto-sociological aspects (also available on website: www.racspa.org).
153
Glossary
LOUISY P., 2006 - Guida all’identificazione dei pesci marini d’Europa e del Mediterraneo (Guide to the
identification of European and Mediterranean sea fishes). Il Castello ed., 432 pp.
One of the most recent guides for the identification of sea fishes, with excellent photographs.
MINELLI A., LA POSTA S., RUFFO A., 1993-95 - Checklist delle specie della fauna italiana (Checklist of species
of Italian fauna). Calderini, Bologna.
This volume lists all the known species of Italian fauna, with its common and correct nomenclature. It is also
available online at www.minambiente.it. For updates on marine species, see www.sibm.it.
PONTI M., MESCALCHIN P., 2008 - Meraviglie sommerse delle Tegnùe. Guida alla scoperta degli organismi
marini (The submerged wonders of the Tegnùe. Guide to the discovery of marine organisms). Editrice La
Mandragora S.r.l.: 421 pp.
A recent volume with many photographs, drawings and maps describing the particular coralligenous
formations in the Northern Adriatic called tegnùe. The volume also describes the individual species
composing these communities.
PRONZATO R. (ed), 2000 - Il corallo. L’oro rosso del Mediterraneo (Coral. The red gold of the Mediterranean).
Bollettino del Mare e degli Istituti Biologici dell’Università di Genova, 64-65 (2000): 94 pp.
A small volume summarising knowledge on problems regarding red coral and its exploitation by man.
RIEDL R., 1991 - Fauna e flora del Mediterraneo (Mediterranean flora and fauna). Franco Muzzio Editore:778
pp.
A guide with many drawings for the identification of the main Mediterranean species.
> Alien: species or populations introduced into a
certain environment by man and not belonging to
the local flora or fauna.
> Association: a permanent aspect, also called
facies, of a biocoenosis when the local
predominance of certain factors produces an
excess of one or of a small number of plant
species (characteristic or preferential) associated
with one another by ecological compatibility
(parameters of environmental factors) and by
chorological affinity (distributed in the same areas).
> Benthos: organisms that live on or in the bottom
of bodies of water.
> Biocenosis: an assemblage of living organisms
inhabiting a common biotope (geographical area)
with homogeneous dominant characteristics; each
biocoenosis includes phytocoenoses (composed
of plants) and zoocoenoses (composed of
animals). The species of a biocoenosis are
statistically faithful to each other and share the
mean values of environmental factors (biotope)
and are not necessarily dominant. The concepts of
biocoenosis and phytosociological association
have a qualititative descriptive meaning, and those
of community and population a quantitative one,
although they are sometimes used in the literature
with similar meanings.
> Bioconcretions: the building of organic and
inorganic substrates by living organisms which
sometimes continues after their death.
Bioconcretions are highly dynamic phenomena
resulting from the balance between the action of
builders and destroyers occurring over a long
period of time.
> Biodestroyers: plant and animal species (bioeroders) which can pierce and bore into living
assemblages or calcareous rock.
> Biokarst/bio-erosion: the consequence of
excavation/erosion of organogenic or calcareous
rocks by living organisms.
> Bionomy: the rules causing and describing the
distribution of organisms (e.g., benthic bionomic
analyses the distribution of benthos by means of
ecological criteria).
> Biotope: a geographical region, of variable
volume or surface area, in which environmental
conditions are relatively stable in time and space,
within the range of evolutionary dynamics of the
components of the land/seascape.
> Builder species: species which build habitats,
providing additional resources or modifying
environmental factors that favour colonisation by
other members of the community.
> Climax: the mature and final stage of a
community, attained by an available population of
organisms in a given environment, under the
influence of climatic and edaphic factors.
> Coastal debris: mobile seabeds rich in sand and
biogenic debris (from shells and skeletons of
marine organisms) which, in the lower infra- and
circalittoral, host a biocoenosis with different
facies according to the dominant animal and/or
plant components.
> Coenosis: the community of plant species and
animals living in a given environment.
> Colonialism: a condition whereby organisms
forming by asexual reproduction remain variably
connected to one another by means of tissues and
organs. In these colonies, organisms may be
morphologically different, carry out different
functions and share food resources.
> Cryptic coloration: (camouflage) colours which
make animals difficult to distinguish against the
background, to reduce predation (e.g., microcavity
affinity, colonial animals, arborescent plants).
> Edaphic: of, or relating to, the soil.
> Endemic: an organism exclusive to a specific
area.
> Engineer species: species which modify the
diversity and/or structure of habitats with their
shape or behaviour, thus affecting the biodiversity
of the community.
> Epibenthos: plants and animals living above or
on organisms (epibionts) or non-living substrates.
> Epiphyte: a plant that grows on another plant
(basiphyte) non-parasitically.
> Euryecious: having a wide range of habitats.
> Euryhaline: able to tolerate a wide range of
salinity.
> Eurythermal: living in a wide range of temperatures.
> Eutrophication: a process of nutrient enrichment
by nitrates and phosphates in aquatic ecosystems,
and now accelerated by human activities
(wastewater disposal and land drainage). It has
negative consequences on the environment.
> Facies: aspect or appearance.
> Filter-feeders (suspensivores): organisms
feeding on suspended particles of matter in water.
> Floristic: relating to floristics, i.e., a branch of
phytogeography that deals with plants and plant
groups from the numerical standpoint.
> Gregariousness: the tendency of animals to
form groups which possess social organisation
(e.g, serpulids, cirripedes, vermetids).
> Interstitial fauna: fauna living in the interstices of
biogenic structures or between grains of sediment.
> Local: species originating in the geographical
area in which they live or at least living there for a
long time and therefore naturalised. The opposite
of alien.
> Lophophore: an organ, usually of a circular or
horseshoe shape, surrounding the mouth and
bearing tentacles, which serve to convey food
particles and provides a respiratory current in
bryozoans, brachiopods, and a few marine worms.
> Maërl: a formation composed of large
accumulations of calcareous, branched algae,
154
principally of the genus Lithothamnion, growing on
mobile substrates exposed to bottom currents.
> Mattes: tiered formations made up of entwined
living and dead rhizomes and roots of Posidonia
oceanica, with interstices filled with sediments.
They alternate with empty areas (intermattes).
> Paucispecific: populations (biocoenoses or
associations) composed of only a few species.
> Phenology: study of the impact of climate on
the seasonal occurrence of flora and fauna, and of
the periodically changing form of an organism,
especially as this affects its relationship with its
environment.
> Photophilic: requiring abundant light for
complete and normal development.
> Photosynthesis: a series of metabolic reactions
occurring in certain autotrophs, whereby the
energy of sunlight, leads to the reduction of carbon
dioxide and the synthesis of organic compounds.
> Phytic: of, or relating to, a plant.
> Phytosociology: a branch of ecology which
deals with the interrelations among the flora of
particular areas and especially with plant
communities.
> Plankton: aquatic organisms that drift with
water movements, generally having no locomotive
organs.
> Recruitment: insertion of juvenile specimens of
one or more species in a biotope or biocoenosis
shared with adults.
> Sciaphilic: thriving in shade, shade-loving.
> Stenohaline: unable to withstand great
variations in salinity.
> Tophule: swollen reserve structures at the base
of primary branches of Cystoseira, to facilitate
resilience in favourable seasons.
> Transparency: one of the properties of water,
through which visible solar radiation (light) can
pass; the extent to which light passes.
> Trophic: relating to the quantity of nutrients
available in the environment.
155
List of species
Acanthaster planci - 136
Acanthella acuta - 52
Acantholabrus palloni - 79, 80
Acasta spongites - 18, 65
Acelia attenuata - 77
Acrothamnion - 34
Acrothamnion preissii - 133
Adeonella - 59, 110
Adeonella calveti - 60
Agelas oroides - 53, 66
Aka - 54
Alcyonium acaule - 13, 16, 58
Alcyonium coralloides - 58
Alpheus - 16
Amphilochus - 75
Annular seabream - 82
Anomia ephippium - 64, 67
Antedon mediterranea - 16, 77
Anthias anthias - 80
Anthithamnion cruciatum - 94
Aora - 76
Aphanius fasciatus - 104
Aplidium - 65
Aplysina - 55
Aplysina aerophoba - 56
Aplysina cavernicola - 16, 53, 58
Apogon imberbis - 83
Apseudes latreilli - 107
Arca barbata - 64
Arca noae - 106
Arthrocladia villosa - 38, 47
Ascidian - 62, 65
Aspidosiphon - 73
Aspidosiphon muelleri - 73
Astroides calycularis - 65, 116,
118, 143
Astrospartus mediterraneus - 77
Athanas - 16
Atlantic lizardfish - 85
Atlantic stargazer - 85, 86
Atlantic torpedo - 85
Axillary wrasse - 81, 86
Axinella - 17
Axinella cannabina - 52
Axinella damicornis - 52, 66
Axinella polypoides - 8, 52
Axinella vaceleti - 52
Axinella verrucosa - 52
Balanus amphitrite - 104
Balanus eburneus - 104
Balanus improvisus - 104
Balanus perforatus - 65
Balanus spongicola - 65
Balssia gasti - 58, 67, 76
Balssia noeli - 76
Barleeia unifasciata - 99, 100
Barnacle - 7, 11, 65, 93, 104, 105
Bathynectes maravigna - 112,
113
Bispira mariae - 63
Black seabream - 82, 83
Black-faced blenny - 84
Black-striped pipefish - 104
Blacktailed wrasse - 81
Blotched picarel - 80, 87
Bogue - 80
Bolma rugosa - 75
Bonellia - 73
Bonellia viridis - 71, 73
Boops boops - 80
Botryllus schlosseri - 104
Bowerbankia gracilis -104
Brachidontes pharaonis - 100
Brittle star - 71, 77
Brown meagre - 78, 83
Brown wrasse - 81
Bucchichi’s goby - 84
Buccinulum corneum - 75
Bugula - 60
Bugula plumosa - 60
Buskea - 59
Cacospongia - 18, 52
Cacospongia mollior - 52
Cacospongia scalaris - 52
Caelorinchus caelorhincus - 113
Calcinus tubularis - 100
Calliostoma - 75
Callochiton achatinus - 73
Callophyllis laciniata - 39
Callopora - 59
Calothrix - 34
Calpensia nobilis - 110
Caprella - 76
Cardinalfish - 83
Cardita calyculata - 99
Caryophyllia smithi - 16, 58
Caulerpa - 133
Caulerpa racemosa - 109, 129
Caulerpa racemosa var.
cylindracea - 133
Caulerpa taxifolia - 129, 133
Cellaria - 59
Cellaria salicornioides - 62
Celleporina caminata - 16
Celleporina mangnevillana - 61,
111
Centrostephanus longispinus 23, 77
Ceramium - 38, 91
Ceramium ciliatum - 94
Ceramium elongata - 94
Ceramium rubrum var. barbatum
- 94
Chaetomorpha mediterranea 93
Chama gryphoides - 64
Charonia charonia - 75
Charonia lampas - 75
Chartella - 59
Chimaera monstrosa - 112
Chiton - 73
Chiton corallinus - 73
Chlamys - 64
Chondrosia reniformis - 53
Chromis chromis - 37, 80
Cidaris cidaris - 77
Ciona edwarsi - 65
Cirriformia filigera - 106
Cirripede - 62
Cladocora - 126, 129
Cladocora caespitosa - 11, 108,
109, 118, 126, 143
Clanculus - 75
Clathrina clathrus - 52
Clathrina coriacea - 142
Clavelina - 65
Cliona - 23, 54, 55, 93, 112
Cliona celata - 54
Cliona janitrix - 54
Cliona schmidti - 54
Cliona viridis - 17, 34, 54, 55, 72
Codium - 34, 39
Codium bursa - 34
Colomastix - 75
Comber - 81, 84
Common dentex - 80, 82, 83,
131, 132
Common octopus - 75
Common pandora - 83
Common seabream - 83
Common stingray - 85, 87
Common two-banded seabream
- 82
Conger conger - 15, 84
Conopea calceola - 65
Conopeum seurati - 104
Coral - 67, 68, 69, 76
Corallina - 93, 94
Corallina elongata - 88, 89, 90,
148
Corallina officinalis - 148
Coralline goby - 84
Coralliophila - 75
Corallium - 68
Corallium rubrum - 16, 58, 62,
66, 75, 115, 119
Cordylophora caspia - 104
Coris julis - 79, 81
Corophium acherusicum - 104,
107
Corophium acutum - 107
Corophium insidiosum - 104
Corophium sextonae - 107
Coryphella - 75
Crab - 70, 76
Crambe - 54
Crella elegans - 53
156
Cressa - 76
Crisia - 60
Cryptonemia - 38
Cryptonemia lomation - 47
Cuckoo wrasse - 80, 81, 86
Cutleria - 34, 39
Cuttlefish - 63
Cyathura carinata - 104
Cymatium cutaceum - 75
Cymatium parthenopaeum - 75
Cymodoce truncata - 76
Cystodytes dellechiajei - 65
Cystoseira - 34, 99, 121
Cystoseira amentacea - 91, 97
Cystoseira amentacea var. stricta
- 97, 99, 100
Cystoseira brachycarpa var.
claudiae - 35, 39
Cystoseira corniculata - 35, 39,
119
Cystoseira dubia - 35, 119
Cystoseira foeniculacea - 34
Cystoseira funkii - 35
Cystoseira jabukae - 35
Cystoseira spinosa - 34, 35
Cystoseira stricta - 97
Cystoseira usneoides - 35, 39,
119
Cystoseira zosteroides - 35, 38,
39, 119
Dasyatis pastinaca - 85, 87
Date mussel - 23, 64
Delectopecten vitreus - 112
Dendrophyllia ramea - 21, 65
Dendropoma - 97, 100, 149
Dendropoma (Novastoa)
petraeum - 95, 97, 99, 100, 116,
121
Dentex dentex - 80, 131, 132
Desmacella inornata - 112
Desmophyllum - 112
Desmophyllum dianthus - 112
Dexamine - 76
Diadem longspine sea urchin - 77
Dictyonella incisa - 53
Dictyonella obtusa - 52
Dictyota - 99
Diplastrella - 54
Diplodus - 81, 82
Diplodus annularis - 82
Diplodus puntazzo - 82, 131, 132
Diplodus sargus sargus - 82,
130, 131
Diplodus vulgaris - 82
Dipolydora - 72
Dipolydora rogeri - 17, 72
Discodoris atromaculata - 23, 24,
56, 75
Ditrupa arietina - 77
Dodecaceria concharum - 72
Doderlein’s wrasse - 81
Dotted sea slug - 55
Dusky grouper - 83, 114, 131,
132
Dusky spinefoot - 87
Dysidea - 18
Dysidea avara - 66
East Atlantic peacock wrasse - 81
Eatonina cossurae - 99
Echinus melo - 23, 34, 77
Elasmopus - 76
Electra posidoniae - 59
Elephant ear - 52
Entalophoroecia - 59
Enteromorpha - 106
Entophysalis - 34
Epinephelus costae - 83
Epinephelus marginatus - 83,
114, 130, 131
Eriphia verrucosa - 100
Erosaria spurca - 75
Etmopterus spinax - 112
Eualus occultus - 76
Euchirograpsus liguricus - 76
Eudendrium - 56, 57
Eudendrium glomeratum - 57
Eulalia viridis - 106
Eumida sanguinea - 106
Eunice - 72
Eunice norvegica - 72, 112, 113,
143
Eunice siciliensis - 72
Eunicella - 48, 75, 76
Eunicella cavolinii - 14, 17, 57,
119, 125
Eunicella singularis - 14, 17, 58,
119
Eunicella verrucosa - 58
European conger - 15, 27, 84, 86
European lobster - 76
European pilchard - 80
False coral - 59
Feather star - 16, 71
Fenestrulina malusii - 59
Ficopomatus - 11, 103, 104, 105,
106
Ficopomatus enigmaticus - 102,
103, 118, 119, 144
Filograna - 63, 67
Filograna implexa - 16
Filogranula gracilis - 112
Filogranula stellata - 112
Fireworm - 72
Flabellina - 75
Forkbeard - 83
Galathea dispersa - 76
Galathea nexa - 76
Galathea strigosa - 76
Galeus melastomus - 112
Gammarus aequicauda - 104
Gammarus insensibilis - 104
Gastrochaena dubia - 64
Gelidium - 34, 47
Gelidium pusillum - 94
Gilthead bream - 83
Gitana - 75
Gnathia maxillaris - 76
Gnathia phallonajopsis - 107
Gobius auratus - 84
Gobius bucchichi - 84
Gobius cruentatus - 84
Gobius geniporus - 84
Gobius vittatus - 84
Goby - 84, 131
Goldband goatfish - 87
Goldblotch - 83
Golden goby - 84
Golden grey mullet - 85
Goniolithon byssoides see
Titanoderma trochanter - 116
Gorgonian - 16
Gorgonian sea fan - 14, 65
Gracilaria - 38
Greater amberjack - 80
Green wrasse - 81
Grouper - 27, 83
Haliclona citrina - 53
Haliclona fulva - 58
Haliclona mediterranea - 53
Haliclona mucosa - 53, 58
Haliclona sarai - 58
Halimeda - 11, 29, 75
Halimeda tuna - 21, 29, 30, 31,
32, 37, 38, 56, 99, 119, 146
Halimeda tuna f. platydisca - 33
Halocynthia papillosa - 16, 17,
65
Haplosyllis depressa chameleon
- 72
Haplosyllis spongicola - 72
Hard tubeworm - 63
Harmothoe - 72
Harmothoe vesiculosa - 112
Harpinia ala - 76
Hediste diversicolor - 104
Helicolenus dactylopterus - 113
Hemimycale columella - 53
Hermit crab - 70, 76
Hermodice carunculata - 58, 72
Hiatella arctica - 64
Hildenbrandia rubra - 118
Hincksinoflustra - 59
Holoturia forskalii - 77
Holoturia poli - 77
Homarus gammarus - 76
Hoplangia durotrix - 58
Hoplostethus mediterraneus 113
Hornera frondiculata - 59
Hyalinoecia - 77
Hyatella arctica - 34
Hydroides - 63, 106
Hyella - 34
Hymedesmia - 54
Hypselodoris - 75
Idmidronea - 59
Inachus - 76
Iphimedia - 75
Ircinia - 55
Ircinia variabilis - 18, 58, 66
Jaeropsis brevicornis - 76
Jania - 34, 47
Jaspis - 55
Jassa marmorata - 107
Jassa ocia - 107
John dory - 84
Kallymenia - 38
Kallymenia patens - 47
Kallymenia spathulata - 47
Knipowitschia panizzae - 104
Kyrtuthrix - 34
Labrus - 81
Labrus merula - 81
Labrus mixtus - 80, 81
Labrus viridis - 81
Lagoon goby - 104
Laminaria ochroleuca - 36, 39,
119
Laminaria rodriguezii - 25, 36, 47
Lanice conchylega - 106, 107
Lappanella fasciata - 79, 80
Large-scaled goby - 84
Large-scaled scorpionfish - 84, 85
Laurencia - 91, 99
Laurencia papillosa - 93
Lekanesphaera hookeri - 104
Lekanesphaera monodi - 104
Lepidasthenia - 72
Lepidochitona caprearum - 99
Lepidonotus - 72
Lepidopleurus cajetanus - 73
Leptocheirus - 75
Leptochelia savignyi - 76, 107
Leptopsammia pruvoti - 16, 58,
65, 67
Liljeborgia - 75
Lima lima - 64
Lissodendoryx - 54
Lithophaga - 93
Lithophaga lithophaga - 23, 34, 64
Lithophyllum - 11, 46, 49, 66, 70,
89
Lithophyllum (= Titanoderma)
ramosissimum - 147
Lithophyllum (Goniolithon)
papillosum - 90, 91, 94, 118
Lithophyllum (Titanoderma)
pustulatum - 31, 46
Lithophyllum (Titanoderma)
trochanter - 89, 91, 116
Lithophyllum byssoides - 89, 90,
91, 92, 93, 93, 94, 95, 97, 99,
118, 121, 149
Lithophyllum cabiochae - 21, 133
Lithophyllum dentatum - 149
Lithophyllum expansum - 15
Lithophyllum frondosum - 11, 119
Lithophyllum incrustans - 31
Lithophyllum lichenoides - 92,
116, 117, 132, 138
Lithophyllum racemus - 45, 149
Lithophyllum stictaeforme - 30,
31, 36, 37, 38, 46, 147
Lithophyllum tortuosum - 92, 118
Lithophyllum trochanter - 94,
118, 147, 148
Lithothamnion - 11, 46, 49, 92
Lithothamnion calcareum see
Phymatolithon calcareum - 115
Lithothamnion corallioides - 43,
45, 47, 115, 118
Lithothamnion fruticulosum - 46
Lithothamnion minervae - 43, 46,
47, 148
Lithothamnion philippii - 31, 36,
46
Lithothamnion valens - 43, 45, 46
Liza aurata - 85
Lobophora - 34, 39
Lobster - 15, 76, 131
Lophelia - 112
Lophelia pertusa - 111, 112
Lophogorgia ceratophyta - 58
Lophogorgia sarmentosa - 119
Lophosiphonia cristata - 93
Lumbrineris - 100, 107
Luria lurida - 75
Lysidice - 72
Lysidice ninetta - 72
Macropodia - 76
Macropodia linaresi - 76
Madrepora - 112
Madrepora oculata - 111, 112,
143
Madrepore - 72
Maera - 76
Maera inaequipes - 107
Margaretta - 59
Margaretta cereoides - 62
Marionia - 75
Marphysa - 72
Mastigocoleus - 34
Mediterranean damselfish - 37,
80, 87
Mediterranean killfish - 104
Mediterranean moray - 15, 27,
84, 86
Mediterranean rainbow wrasse 79, 81, 86
Mediterranean slipper lobster 115
Megabalanus tulipiformis - 65
Melon sea urchin - 77
Mercierella enigmatica - 103
Mesophyllum - 11, 66
Mesophyllum alternans - 20, 21,
24, 30, 31, 32, 36, 46, 127, 133
Mesophyllum lichenoides - 15,
31, 32, 36, 46, 118, 147
Microcoleus - 34
Microcosmus - 65
Microcosmus sulcatus - 16
Micromesistius poutassou - 113
Microporella - 59
Miniacina miniacea - 93
Mottled grouper - 83
Mullus barbatus - 85
Mullus surmuletus - 85
Munida intermedia - 112
Munida tenuimana - 112
Muraena helena - 15, 27, 84
Muricopsis cristata - 75
Mussel - 7, 11
Mustelus mustelus - 85
Mycale - 52
Mycteroperca rubra - 83
Myriapora truncata - 21, 59, 111
Mytilaster lineatus - 104
Mytilaster marioni - 104
Mytilaster minimus - 99, 106
Mytilus galloprovincialis - 106
Myxicola aestetica - 63
Nausithoe punctata - 18, 55, 56
Neanthes succinea - 104
Nematopagurus longicornis - 76
Neogoniolithon - 11, 95
Neogoniolithon brassica-florida 31, 46, 89, 90, 91, 94, 95, 97, 99,
118, 149
Neogoniolithon mamillosum - 15
Neosimnia - 75
Neosimnia spelta - 58, 74
Neptune grass - 123
Nereis falsa - 106
Neurocaulon - 38
Nithophyllum tristromaticum - 39
Notomastus lineatus - 106
Nursehound - 85
Oblada melanura - 80
Octopus - 63, 76
Octopus vulgaris - 75
Odondebuenia balearica - 84
Onchidella celtica - 99
Ophidiaster ophidianus - 77
Ophioderma - 71
Ophioderma longicaudum - 77
Ophiopsila aranea - 47
Ophiotrix fragilis - 77
Ornate wrasse - 81
Oscarella - 53
Oscarella lobularis - 40, 49, 53, 66
Oscillatoria - 34
Osmundaria - 39
Osmundaria volubilis - 47
Oyster - 7, 11
Pachastrella monilifera - 112
Pachygrapsus marmoratus - 100
Pachygrapsus maurus - 100
Pachygrapsus transversus - 100
Padina pavonica - 99
Pagellus bogaraveo - 113
Pagellus erythrinus - 83
Pagrus pagrus - 83
Pagurus anachoretus - 76
Pagurus vreuxi - 76
Painted comber - 81, 84
Palinurus elephas - 15, 76
Palmophyllum - 16, 34
Palola siciliensis - 100
Pandalina brevirostris - 76
Parablennius rouxi - 84
Parablennius zvonimiri - 101
Paramuricea - 48
Paramuricea clavata - 13, 52, 58,
62, 63, 64, 72, 75, 76, 119, 125
Paranthura nigropunctata - 76
Parasmittina - 110
Parazoanthus - 48, 50
Parazoanthus axinellae - 11, 16,
17, 58, 119
Parerythropodium coralloides 17, 58
Patella caerulea - 99
Patella ulyssiponensis - 99, 101
Pencil sea urchin - 77
Pentapora - 59, 110
157
158
Pentapora fascialis - 16, 21, 61,
62, 128
Pentapora ottomülleriana - 110
Percnon gibbesi - 100
Periclimenes sagittifer - 76
Periclimenes scriptus - 76
Perinereis cultrifera - 100, 106
Petricola lithophaga - 64
Petrosia - 23, 55, 75
Petrosia ficiformis - 16, 24, 53,
55, 58, 66
Peyssonnelia - 11, 16, 24, 34,
38, 39, 46, 66, 75
Peyssonnelia bornetii - 28
Peyssonnelia harveyana - 46, 47
Peyssonnelia inamoena - 46, 47
Peyssonnelia magna - 33, 47
Peyssonnelia polymorpha - 31,
33, 47
Peyssonnelia rosa-marina - 31,
33, 45, 47
Peyssonnelia rosa-marina f.
saxicola - 33
Peyssonnelia rubra - 15
Phaeophila - 34
Phascolosoma strombii - 73
Pholas dactylus - 67
Phorbas - 54
Phorbas tenacior - 53, 54, 66
Phycis blennioides - 113
Phycis phycis - 83
Phyllariopsis brevipes - 36
Phyllariopsis purpurascens - 36,
39
Phyllophora - 39
Phyllophora crispa - 47
Phyllophora heredia - 39
Phymatolithon calcareum - 43,
45, 47, 115, 118
Phymatolithon lenormandii - 118
Picarel - 80, 87
Pilumnus - 76
Pinna nobilis - 64
Pinna rudis (= Pinna pernula) - 64
Pisinna glabrata - 99
Plagioecia inoedificata - 111
Plagioecia platidyscus - 111
Platydoris argo - 145
Platynereis dumerilii - 100
Pleraplysilla spinifera - 51, 52, 69
Plesionika narval - 76
Poecillastra compressa - 112
Polycarpa - 65
Polydora - 11, 34
Polydora ciliata - 104
Polydora hoplura - 72
Polysiphonia - 34, 38, 39, 91, 118
Polysiphonia opaca - 94
Polysiphonia sertularioides - 94
Pomatoceros lamarckii - 106
Pomatoceros triqueter - 63
Posidonia - 31, 59, 72, 77, 105,
110
Posidonia oceanica - 7, 14, 18,
24, 49, 50, 70, 79, 80, 83, 85, 97,
108, 118, 122, 123, 128, 138, 140
Prawn - 70
Protula - 21, 63, 67
Pseudosimnia - 75
Pseudosimnia carnea - 67
Pteria hirundo - 64
Pterocladia melanoidea - 93
Ptilophora mediterranea - 38
Puellina corbula - 111
Puellina pedunculata - 111
Pyrgoma anglicum - 65
Pyura - 65
Raspaciona - 54
Red coral - 8, 11, 16, 49, 54, 56,
66, 67, 68, 69, 76, 115, 125, 132,
135, 138
Red dead man’s fingers - 16
Red mullet - 85
Red sea fan - 63, 64, 65
Redcoat - 87
Red-mouthed goby - 84
Reptadeonella violacea - 110
Reteporella - 59, 110
Reteporella grimaldii - 62
Reteporella septentrionalis - 67
Rhynchozoon - 110
Rochinia rissoana - 112
Rodriguezella - 36, 38
Rodriguezella bornetii - 36
Rodriguezella pinnata - 36
Rodriguezella strafforelloi - 36,
119
Rynchozoon - 62
Rythiphloea tinctoria - 47
Sabella pavonina - 63
Sabella spallanzanii - 63
Sabellaria - 11, 105, 106, 107
Sabellaria alveolata - 7, 103, 105,
107
Sabellaria halcocki - 105, 106
Sabellaria spinulosa - 105
Saddled bream - 80
Salp - 83
Salmacina dysteri - 21
Sarcotragus foetidus - 52, 58
Sardina pilchardus - 80
Sargassum - 34, 119
Sargassum hornschuchii - 34, 39
Sargassum trichocarpum - 34,
39
Sargocentron rubrum - 87
Sarpa salpa - 83
Savalia (= Gerardia) - 16, 58
Savalia (= Gerardia) savaglia - 13,
58, 76, 116
Scale-rayed wrasse - 80
Scartella cristata - 101
Schizobrachiella errata - 110
Schizobrachiella sanguinea - 62,
110
Schizomavella - 110
Schizomavella auriculata hirsuta
- 62
Schizomavella cornuta - 61
Schizoporella - 110
Schizotheca serratimargo - 59
Schizothrix - 34
Sciaena umbra - 78, 83
Scorpaena porcus - 84
Scorpaena scrofa - 84, 85
Scorpionfish - 84
Scrupocellaria - 60
Scyliorhinus canicula - 85
Scyliorhinus stellaris - 85
Scyllarides - 76
Scyllarides latus - 115
Scyllarus - 76
Scyllarus arctus - 76
Sea cucumber - 77
Sea fan - 146
Sea fan - 56, 59, 62, 72, 77, 80,
86, 125, 128, 131, 134, 141, 143
Sea lace - 59
Sea lily - 71
Sea star - 71
Sea urchin - 71, 75, 82
Seabream - 81, 82
Seriola dumerili - 80
Serpula vermicularis - 63
Serpulorbis arenaria - 64
Serranus cabrilla - 81, 84
Serranus scriba - 81, 84
Setosella cavernicola - 111
Sharpsnout seabream - 82, 131
Shrimp - 70
Siganus luridus - 87
Simnia - 75
Slender goby - 84
Slipper lobster - 76
Small-spotted catshark - 85
Smittina cervicornis - 21, 59, 62,
67, 110
Smoothhound - 85
Sole - 85, 131
Solea - 85
Sparus aurata - 83
Spatangus purpureus - 47
Spermothamnion - 38
Sphaerechinus granularis - 11,
23, 77
Sphaerechinus granularis - 34
Sphaeriodiscus placenta - 77
Sphaeroma serratum - 104
Sphyraena viridensis - 80
Spicara maena - 80
Spicara smaris - 80
Spiny cushion star - 77
Spirastrella - 54
Spirobranchus polytrema - 63
Spirorbis - 67
Spiroxya - 112
Spondyliosoma cantharus - 82,
83
Spondylus gaederopus - 64
Spondylus gussonii - 112
Spongia - 55
Spongia lamella - 52
Spongia officinalis - 52
Spongia virgultosa - 55, 58
Spongites fruticulosus - 31, 46
Sporochnus pedunculatus - 38,
47
Sporolithon ptichoides - 31
Spyroxia - 54
Squat lobster - 76
Squid - 63
Stenocyathus vermiformis - 112
Stenothoe - 75
Stigonema - 34
Stoeba - 55
Striarca lactea - 106
Striped goby - 84
Striped red mullet - 85
Stylocidaris affinis - 22, 23, 77
Subadyte cfr. pellucida - 112
Swallowtail seaperch - 80, 86
Syllis - 100
Symphodus - 81
Symphodus doderleini - 81
Symphodus mediterraneus - 81
Symphodus melanocercus - 81
Symphodus tinca - 81
Syngnathus abaster - 104
Synodus saurus - 85
Taenioma nanum - 93
Tanais cavolini - 76
Tenarea - 92
Tenarea tortuosa - 90, 91, 94
Tenarea undulosa - 118
Terebella lapidaria - 106
Thalassoma pavo - 81
Thoosa - 54
Thoralus cranchii - 76
Thorogobius macrolepis - 84
Thuridilla - 75
Timea - 54
Torpedo nobiliana - 85
Trachinus - 85
Trididemnum - 65
Triptolemus - 55
Tryphosella simillima - 76
Trypterigion delaisi - 84, 101
Trypterigion melanurus - 101
Trypterigion tripteronotus - 101
Turbicellepora incrassata - 61, 62
Turtle - 79
Tylodina perversa - 55
Ulva - 106
Umbraculum mediterraneum 75
Umbraulva olivascens - 39
Uncionella lunata - 76
Upeneus moluccensis - 87
Uranoscopus scaber - 85, 86
Valonia - 34
Vermetus - 64
Vermetus triquetrus - 95, 97
Verruca spengleri - 65
Weever - 85
White coral - 72, 111, 112, 113,
129, 131, 143
White gorgonian - 14
White seabream - 82, 130, 131
Womersleyella - 34, 133
Womersleyella (Polysiphonia)
setacea - 133
Yellow polipe - 16, 17
Yellowmouth barracuda - 80
Zanardinia - 34, 39
Zeus faber - 84
Zonaria - 39
Zonaria tournefortii - 39
159
We would like to thank Luca Lantieri of the
University of Genoa, and Elisabetta Massaro,
Sara Queirolo and Rossana Simoni of SIBM for
their valuable collaboration.
We would also like to remember Anna Maria
Proietti who collaborated with Francesco Cinelli
on the iconographic section.
In the chapter on seaweeds, the section on
coralligenous assemblages was written by
Thalassia Giaccone and Giuseppe Giaccone.
The section on rhodolith beds is by Thalassia
Giaccone, Giuseppe Giaccone, Daniela Basso
and Guido Bressan.
The checklist of all the phytosociological units
of the Mediterranean Sea is published in the
“Proceedings of 1st Mediterranean Symposium
on Marine Vegetation” (Ajaccio,
3-4 October 2000).
The authors assume full responsibility for any
errors and omissions in the text.
The volume was produced with funds from the
Italian Ministry of the Environment and
Territorial Protection
Printed in september 2009
by Arti Grafiche Friulane / Imoco spa - Udine
Printed in Italy