Multi-scale biodiverity patterns in phytoplankton from coastal lagoons: the Eastern Mediterranean

Abstract

1 - The phytoplankton from Eastern Mediterranean coastal lagoons is analysed using a multi-scale approach, with the aim of testing if phytoplankton variations follow a hierarchical scheme based on eco-geographical location. The scale similarity is examined by using a taxonomic metric based on the Kullback-Leibler divergence and a related similarity index. 2 - A hierarchical sampling design was used to investigate variations in taxonomic composition and richness of phytoplankton assemblages. Data analyzed collected during summer season in 3 coastal lagoons in the Mediterranean Eco-region: two are located in Turkey (Akg�l and Paradeniz) and one is located in Greece (Korission). According to the Mediterranean typology, all lagoons are large, non-tidal and have mean salinity regimes of oligohaline (Akg�l), polyhaline (Paradeniz) and euhaline (Korission) designations. 3 - The taxonomic composition of phytoplankton assemblages varied markedly among lagoons, with the most representative phytoplankton in terms of taxa richness belonged to Chlorophyceae (33.33%) in Akg�l, to Dinophyceae (50.00%) in Paradeniz and to Dinophyceae (30.77%) in Korission. 4 - Within-habitat similarity was very high in all habitats and lagoons. At an ecosystem scale, phytoplankton was highly homogeneous in Akg�l and Paradeniz, suggesting that the distinctive physiognomic traits of the habitats exert a limited effect. In contrast, the phytoplankton is significantly heterogeneous in Korission, mostly because of the effect of the heterogeneous habitats, in fact the three sampled habitats showed well-differentiated characteristics. 5 - At an eco-regional scale, the pattern of similarity among lagoons suggests that local conditions (particularly salinity) and geographical location play roles of a comparable importance in determining the dissimilarity among phytoplankton guilds. 6 - The similarity index between adjacent lagoons having different salinity (Akg�l and Paradeniz) was comparable to the one between lagoons with similar salinity but different geographical location. This suggests that local conditions and geographical factors act in a complex way.