macrophytes as biological element for the assessment and

Biol. Mar. Mediterr. (2010), 17 (1): 67-70
A. Sfriso, C. Facca
Department of Environmental Sciences, University of Venice, Calle Larga, S. Marta, 2137, Venice, Italy.
[email protected]
MACROPHYTES AS BIOLOGICAL ELEMENT FOR THE
ASSESSMENT AND MANAGEMENT OF TRANSITIONAL WATER
SYSTEMS IN THE MEDITERRANEAN ECOREGION
L’ELEMENTO BIOLOGICO MACROFITE PER LA VALUTAZIONE
E LA GESTIONE DEGLI AMBIENTI DI TRANSIZIONE
NELL’ECOREGIONE MEDITERRANEA
Abstract – Macrophytes (macroalgae and angiosperms) are one of the biological quality elements
(BQE) proposed by the European Water Framework Directive (WFD, 2000/60/EC) to assess the
ecological status of coastal waters and transitional systems. Here the application of the available indices
(MaQI, Italy and EEI, Greece) set up to attempt to the WFD requirements for the Mediterranean
Ecoregion are presented and applied to 5 Venice Lagoon areas of different ecological status. Indices are
based on a different rationale but whereas MaQI can be used also in the presence of a single taxon with
a negligible biomass coverage, EEI requires a coverage >30%.
Key-words: phytobenthos, aquatic plants, environmental monitoring, MaQI, EEI, Venice Lagoon.
Introduction – The first studies that related macrophytes to some environment
pollution events go back to the 1970s. Phytosociological studies and the
Rhodophyceae/Phaeophyceae ratio (R/P) were the most interesting application
of macrophyte vegetation in the coastal waters of Trieste, Marsiglia and in some
Sardinia and Sicilia areas but only in the 2000s, under the WFD promotion, the
first well structured phytobenthic indices were proposed (Giaccone & Catra, 2004).
In 2001, some Greek researchers proposed the application of the Ecological
Evaluation Index (EEI) based on the per cent coverage and macrophyte distinction
in two functional groups: the late successional (ESG I) and the opportunistic (ESG
II) species (Orfanidis et al., 2001, 2003). The index is applied both to coastal and
transitional waters and now it is also accepted by Cipro, Slovenia and Croatia. In Italy,
since the 2002 (Sfriso et al., 2002), a strong relationship between the Rhodophyta/
Chlorophyta ratio (R/C) and the environment ecological status was recorded and
this index was employed for the assessment of both coastal waters and transitional
systems. Concurrently, for transitional systems, a more precise methodology: the
Macrophyte Quality Index (MaQI), both in an expert (E-MaQI) and rapid (R-MaQI)
version was set up (Sfriso et al., 2007, 2009). In 2009 MaQI was accepted by Italy for
the national transitional water assessment.
At present an intercalibration exercise between the Mediterranean Geographycal
Intercalibration Groups (Med-GIG) of each Mediterranean Member State is
occurring by applying the national method of Greece (EEI) and the national method
of Italy (MaQI).
In this paper an example of their application in stations of different ecological
status sampled in Venice Lagoon in 2008 is presented.
Materials and methods – Fig. 1 shows the central part of the Venice Lagoon and
the 5 sampling sites. Each station has a ray of 15-20 m and it includes both soft and
hard substrata. Macroalgae have been recorded in June and October 2008 by SCUBA
divers. Concurrently, total macrophyte coverage was determined. The coverage of the
dominant taxa was obtained by sorting and weighting the dominant taxa of 3-6 samples
recorded by a rake according to ISPRA sampling methodologies (ISPRA, 2008) and
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A. Sfriso, C. Facca
their successive integration which is under publication. The reference EQR values are
1.03 and 1.00 for euhaline and polyhaline stations, respectively (Sfriso et al., 2009).
Fig. 1 - Central part of the Venice Lagoon and sampling stations. Assessment by MaQI application.
Parte centrale della laguna di Venezia e stazioni di campionamento. Valutazione dello stato ecologico
mediante l’applicazione dell’indice MaQI.
Results – Total macrophytes ranged from 107 taxa (105 macroalgae and 2
angiosperms) at St. 1 (San Nicolò) to 17 taxa at St. 5 (Marco Polo Airport) (Tab. 1).
The numbers are the sum of the taxa recorded in June and October and, obviously
they are higher than each single sampling. Seagrasses were recorded only at St. 1
(San Nicolò) and at St. 2 (Alberoni Ottagono). The R/C ratio, ranged from 1.8 at
St. 1 to 0.4 at St. 5. By normalising the values with the highest values recorded in
the reference areas (2.21 and 2.00 for euhaline and polyhaline stations, respectively,
Sfriso et al., 2009) the station assessment is “High” for St. 1, “Good” for Sts. 2
(Alberoni Ottagono) and 3 (Lido watershed), “Poor” for St. 4 (San Giuliano) whereas
at station 5 (Marco Polo Airport) the index is not applicable because of the number
of species is lower than 20.
The results obtained by applying E-MaQI are similar to the R/C assessment,
except at St. 3 (Lido watershed) where the classification results to be “Moderate”.
However, the normalised scores obtained by the two indices are very close one to the
other and to the boundary classes. Also E-MaQI is not applicable at St. 5 (Airport)
because of the low number of taxa.
On the contrary R-MaQI can be applicable also if macrophytes are quite missing
and St. 5 (Marco Polo Airport), as expected, is assessed as “Bad”. For all the other
stations the environmental assessment is the same of that obtained by E-MaQI.
EEI is applicable only at Sts. 1, 2, 3 where macrophyte biomass was higher
than 30%. However, the classification is the same only at St. 2 (Alberoni Ottagono)
whereas the assessment of the other two stations differs even of two classes: St. 1 (S.
Nicolò) is assessed as “Moderate” and St. 3 (Lido watershed) is assessed as “Bad”.
In fact, that index is mainly based on macrophyte coverage whereas MaQI takes
Macrophytes as biological element for the assessment and management of transitional water systems
69
into consideration mainly the presence of high score taxa and their relationship with
some environmental parameters and pollutants.
Tab. 1 - Check-List of macrophytes (macroalgae and angiosperms) recorded in some stations of
the Venice Lagoon in June and October 2008 and indices of ecological status application.
Lista delle macrofite (macroalghe e angiosperme) raccolte in alcune stazioni della laguna di Venezia in giugno ed in ottobre 2008 ed applicazione di indici di stato ecologico.
Conclusions – Macrophytes are very sensitive to the ecological conditions of
transitional waters and some indices can supply a very useful tool both in their
monitoring and management. In fact, the presence/absence of high score taxa such
as angiosperms and many macroalgae is strongly related to the environment trophic
state and pollution level. Therefore, the preservation or restoring of angiosperm
meadows should be the first objective for the transitional system management.
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A. Sfriso, C. Facca
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