Proceedings of the Second Mediterranean Symposium on Marine

PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION (ATHENS, 12-13 DECEMBER 2003)
194
Six samplings were carried out between
summer 1998 and spring 2002 (August 98,
March 99, June 99, June 01, September 01 and
March 02) in order to monitor <strong>the</strong> marine
benthic vegetation characteristics. The sampling
was destructive (1 random sample from a
permanent station-square 5 x 5 m per sampling
period) on a quadrate 20cm x 20cm, which is
considered to be <strong>the</strong> minimal sampling area in
<strong>the</strong> case <strong>of</strong> <strong>the</strong> <strong>Mediterranean</strong> infralittoral
communities.
Phytobenthos community structure was
analyzed in terms <strong>of</strong> species number, total
coverage, Shannon-Weaver diversity (H’, log2
basis) and Pielou evenness (J’) indices.
Fig. 1: The study area
The Ecological Evaluation Index (EEI) was calculated according to Orfanidis et al. (2001),
described also on <strong>the</strong> site: www.fishri.gr (Laboratories / Marine Ecology / Water quality).
The EEI is an original metric for <strong>the</strong> ecological status evaluation based on <strong>the</strong> concept <strong>of</strong>
morphological and functional groups (Littler and Littler 1980; 1984). The species were
divided in two Ecological State Groups (ESG):
In <strong>the</strong> ESG I were grouped <strong>the</strong> thick lea<strong>the</strong>ry, <strong>the</strong> articulate upright calcareous and <strong>the</strong>
crustose calcareous species. Most <strong>of</strong> <strong>the</strong>m are k-selected species. In <strong>the</strong> ESG II were
grouped <strong>the</strong> foliose, <strong>the</strong> filamentous and <strong>the</strong> coarsely branched upright species. Most <strong>of</strong>
<strong>the</strong>m are r-selected species.
Each sampling station was classified in one <strong>of</strong> <strong>the</strong> five classes <strong>of</strong> ES after a simple crosscomparison
<strong>of</strong> <strong>the</strong> coverage value <strong>of</strong> <strong>the</strong>
ESG I and <strong>the</strong> ESG II on a matrix (Fig. 2). The
numerical scoring system was used to
express <strong>the</strong> category <strong>of</strong> ecological status as
a number (Bad=2, Low=4, Moderate=6,
Good=8 and High=10).
RESULTS
In total 60 taxa were identified (12
Chlorophyceae, 16 Phaeophyceae and 32
Rhodophyceae). At all <strong>the</strong> studied stations
<strong>the</strong> Rhodophyceae were qualitatively
Fig. 2: Matrix for <strong>the</strong> evaluation <strong>of</strong> <strong>the</strong> ESC
dominant and <strong>the</strong> Phaeophyceae were
quantitatively dominant (Table 1).
The canopy layer <strong>of</strong> <strong>the</strong> vegetation was well developed at Stations 1, 4, 5 and 6, mainly
due to <strong>the</strong> presence <strong>of</strong> Cystoseira species. O<strong>the</strong>r species, e.g. Dictyopteris
membranacea, formed a pseudo-canopy layer when <strong>the</strong>y were massively present. A
well-developed bushy layer, composed mainly by Jania rubens, Laurencia optusa,