Other types of bioconcretions
Transcript
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 89 90 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. 91 92 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 93 94 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 95 96 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 97 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 98 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 99 100 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 101 ■ Polychaete reefs 102 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 103 104 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 105 106 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 107 108 ■ 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 119 120 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 121 122 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. 123 124 ■ 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. 125 126 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. 127 128 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 129 130 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 131 132 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. 135 136 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. 137 138 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