Proceedings of the Second Mediterranean Symposium on Marine
Proceedings of the Second Mediterranean Symposium on Marine
Proceedings of the Second Mediterranean Symposium on Marine
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PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION (ATHENS, 12-13 DECEMBER 2003)<br />
218<br />
MATERIALS AND METHODS<br />
The indices were applied <strong>on</strong> existing data from <str<strong>on</strong>g>the</str<strong>on</strong>g> Maliakos Bay (Aegean Sea, Greece)<br />
(Chryssovergis & Panayotidis, 1995). The data was quantitative and c<strong>on</strong>sisted <str<strong>on</strong>g>of</str<strong>on</strong>g> a set <str<strong>on</strong>g>of</str<strong>on</strong>g> five<br />
stati<strong>on</strong>s al<strong>on</strong>g an eutr<str<strong>on</strong>g>of</str<strong>on</strong>g>icati<strong>on</strong> gradient (Fig. 1) for two years (summer and winter m<strong>on</strong>ths).<br />
Fig 1: Map <str<strong>on</strong>g>of</str<strong>on</strong>g> Maliakos Bay (Greece) showing <str<strong>on</strong>g>the</str<strong>on</strong>g> five sampling stati<strong>on</strong>s al<strong>on</strong>g a eutr<str<strong>on</strong>g>of</str<strong>on</strong>g>icati<strong>on</strong> gradient from<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> Sperchios River mouth (stati<strong>on</strong>s A & B), from were <str<strong>on</strong>g>the</str<strong>on</strong>g>re is an important nutrient input, towards <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
Aegean Sea (stati<strong>on</strong>s C & E).<br />
The Ecological Evaluati<strong>on</strong> Index<br />
The EEI was calculated according to Orfanidis et al. (2001). The macrophyte species<br />
were divided in two Ecological State Groups. In ESG I were grouped <str<strong>on</strong>g>the</str<strong>on</strong>g> thick lea<str<strong>on</strong>g>the</str<strong>on</strong>g>ry,<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> articulate upright calcareous and <str<strong>on</strong>g>the</str<strong>on</strong>g> crustose calcareous species, most <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>m being<br />
k-selected species. In ESG II were grouped <str<strong>on</strong>g>the</str<strong>on</strong>g> foliose, <str<strong>on</strong>g>the</str<strong>on</strong>g> filamentous and <str<strong>on</strong>g>the</str<strong>on</strong>g> coarsely<br />
branched upright species. Most <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>m are r-selected species. Each sampling site was<br />
classified in <strong>on</strong>e <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> five ESC after a cross-comparis<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> mean abundance value<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> ESG I and II, <strong>on</strong> a matrix. Additi<strong>on</strong>ally to <str<strong>on</strong>g>the</str<strong>on</strong>g> mean abundance value, <str<strong>on</strong>g>the</str<strong>on</strong>g> relative<br />
abundance value for <str<strong>on</strong>g>the</str<strong>on</strong>g> two groups was applied.<br />
Tax<strong>on</strong>omic diversity indices<br />
According to Warwick & Clarke (2001) <str<strong>on</strong>g>the</str<strong>on</strong>g> average tax<strong>on</strong>omic distinctness, ∆ + , is <str<strong>on</strong>g>the</str<strong>on</strong>g> mean<br />
number <str<strong>on</strong>g>of</str<strong>on</strong>g> steps up <str<strong>on</strong>g>the</str<strong>on</strong>g> hierarchy that must be taken to reach a tax<strong>on</strong>omic rank comm<strong>on</strong><br />
to two species, computed across all possible pairs <str<strong>on</strong>g>of</str<strong>on</strong>g> species in an assemblage. The<br />
species are placed within a tax<strong>on</strong>omic hierarchy, based <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> Linnean classificati<strong>on</strong><br />
(phylum, class, order, family, and genus). Thus, if two species are c<strong>on</strong>generic, <strong>on</strong>e step<br />
(species-to-genus) is necessary to reach a comm<strong>on</strong> node in <str<strong>on</strong>g>the</str<strong>on</strong>g> tax<strong>on</strong>omic tree. If <str<strong>on</strong>g>the</str<strong>on</strong>g> two<br />
species bel<strong>on</strong>g to different genera but <str<strong>on</strong>g>the</str<strong>on</strong>g> same family, two steps will be necessary<br />
(species-to-genus, and genus-to-family); and so <strong>on</strong>, with <str<strong>on</strong>g>the</str<strong>on</strong>g>se numbers <str<strong>on</strong>g>of</str<strong>on</strong>g> steps averaged<br />
across all species pairs. If ∆ + is <str<strong>on</strong>g>the</str<strong>on</strong>g> mean path length through <str<strong>on</strong>g>the</str<strong>on</strong>g> tax<strong>on</strong>omic tree<br />
c<strong>on</strong>necting each pair <str<strong>on</strong>g>of</str<strong>on</strong>g> species, Λ + is simply <str<strong>on</strong>g>the</str<strong>on</strong>g> variance <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>se pairwise path lengths<br />
and could be seen as an index <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> “complexity” <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> hierarchical tree (Fig. 2).