Biol. Mar. Mediterr. (2010), 17 (1): 162-163
E. Cecchi, L. Piazzi*
ARPAT – Area Mare, Via Marradi, 114 – 57124 Livorno, Italia.
[email protected]
*CIBM, Centro Interuniversitario di Biologia Marina, Livorno, Italia.
A NEW METHOD FOR THE ASSESSMENT OF THE
ECOLOGICAL STATUS OF CORALLIGENOUS ASSEMBLAGES
UN NUOVO METODO PER LA DETERMINAZIONE
DELLA QUALITÀ ECOLOGICA DEI POPOLAMENTI CORALLIGENI
Abstract – The paper proposed a new method for the assessment of ecological status of Mediterranean
coralligenous assemblages. The proposal is based on data obtained from photographic samplings carried
out by ARPAT in 5 locations along the coast and islands of Tuscany. Results showed that the proposed
method allowed to clearly separate the studied locations, in agreement with other methods already used
in monitoring survey.
Key-words: coralligenous assemblages, environmental quality, Tuscany.
Introduction – Coralligenous habitat represents one of the most important
Mediterranean coastal systems in relation to its distribution, biodiversity and
production (Ballesteros, 2006). The maintenance of this habitat is due to a balance
of constructive and destructive forces and each impact can influence this balance.
Thus, coralligenous assemblages are considered sensitive to disturbance and they can
represent effective bio-indicators in monitoring programs (Balata et al., 2005; Piazzi
et al., 2010). We proposed a new method for the assessment of Ecological Status of
Coralligenous Assemblages (ESCA index) .
Materials and methods – The proposal is based on data obtained from samplings
carried out by ARPAT in 5 locations along the coast (Meloria Shoals, Livorno, Vada
Shoals, Monte Argentario) and islands (Montecristo) of Tuscany. In each location,
two sites were chosen and in each site two areas were sampled; in each area 15
photographic samples of 1878 cm 2 were collected on vertical bottom at the depth of
30 m. Images were analyzed by Image J to evaluate the cover of the main taxa or
groups. An ecological values ranging between 1 and 10 was attributed to each taxon/
group identified with photographic sampling (Tab. 1).
Tab. 1 - Sensitivity levels of the taxa/groups identify with photographic sampling.
Sensitivity levels dei taxa/gruppi identificati mediante campionamento fotografico.
Taxa/group
Gorgonacea
Halimeda tuna, Cystoseira spp.
Flattened corticated Rhodophyta, erect Bryozoa, Madreporaria
Large-size terete Rhodophyta with cortication
Flabellia petiolata
Zanardina typus, Hydrozoa, Tunicata, encrusting Bryozoa
Peyssonnelia spp, Palmophyllum crassum, Valonia spp., Porifera, Polychaeta
Encrusting Corallinales
Dictyotales, articulated Corallinales
Turf, Caulerpa spp.
Sens. lev.
10
9
8
7
6
5
4
3
2
1
A new method for the assessment of the ecological status of coralligenous assemblages
163
Three descriptors have been considered: ecological values of organisms (values
attributed at each sample correspond to values of the organism with the highest
sensitivity level present in the sample), number of organisms/groups, heterogeneity
of assemblages (calculated through PERMDISP analysis; Anderson, 2006). Values of
Environmental Quality (EQV) calculated from these three descriptors were divided
from reference values (values obtained from Montecristo Island) to obtain the
Environmental Quality Ratio (EQR’). The EQR of the water bodies was evaluated
as the mean of the three EQR’. According to the European Water Framework
Directive, five ecological status classes were defined (0-0.4 bad, 0.4-0.55 poor, 0.550.7 moderate, 0.7-0.85 good, 0.85-1.0 high).
Results – The application of the proposed method to the 4 locations sampled
along the coast of Tuscany, showed that Monte Argentario resulted in high condition,
while the other locations resulted in good condition (Tab. 2).
Tab. 2 - Results of application of the new method to 4 locations of Tuscany coasts.
Risultati dell’applicazione del nuovo metodo (E.S.C.A.) nelle quattro località toscane.
Location
Argentario Month
Vada Shoal
Meloria Shoal
Calafuria (LI)
EQR’
sensitivity level
0.97
0.92
0.90
0.90
(high)
(high)
(high)
(high)
EQR’
Number of
taxa/group
0.99 (high)
0.89 (good)
0.82 (good)
0.77 (good)
EQR’
heterogeneity
EQR
Ecological
status
0.79 (good)
0.66 (moderate)
0.61 (moderate)
0.54 (moderate)
0.92
0.83
0.78
0.74
High
Good
Good
Good
Conclusions – The proposed method allowed to clearly separate the studied
locations, in agreement with results obtained with other methods already used in
monitoring programs (eg. CARLIT). The three selected descriptors sowed similar
patterns in the attributing ecological values at the five locations. The widest range
of EQR values was related to the level of heterogeneity, that seems to represent a
valid descriptor of ecological quality of coralligenous assemblages. The proposed
method shows the advantages that it is not a destructive method, it does not require
highly specialized taxonomists and it considers different ecological aspects of the
assemblages. However, this method needs to be tested on a large set of data, in
order to evaluate its effectiveness and to highlighted possible differences related to
geographic areas.
References
ANDERSON M.J. (2006) - Distance-based test for homogeneity of multivariate dispersions.
Biometrics, 62: 245-253.
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PIAZZI L., BALATA D., CECCHI E., CINELLI F., SARTONI G. (2010) - Species composition
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