La comunità dei Peracaridi come indicatore di eterogeneità spaziale in ambienti lagunari adriatici.

The community of Peracarids from hard bottoms was studied in 2004 in two lagoons at different climatic and hydromorphologic regimes: the Sacca di Goro in the Po river delta, of about 26 km2 and depth between a few centimetres and over 2 metres, and the Lesina lagoon, in the Gargano promontory, of about 53 km2, almost uniform depth of about 80 cm and two narrow lagoon mouths. The differences between the two basins, outlined by the multivariate analysis, were mainly due to the different abundance of the 30 identified species rather than to their mere presence. Peculiar elements were not lacking, and were particularly related to seawater exchange at Goro, and to a moderate desalination, that involved almost the entire basin, at Lesina. This condition resulted in a strong biocenotic homogeneity, with dominance of the isopod Sphaeroma serratum and presence of other eurihaline species such as Gammarus sp. pl., Echinogammarus pungens and Melita palmata. At Goro, instead, a more marked spatial heterogeneity could be noticed, related to an active harbour and to the noteworthy freshwater supply from the Po river, that also generated some localized estuarine communities. Globally, the lagoon was characterized by Corophium sp. pl. and Melita palmata. The comparison with data from previous years in the Sacca di Goro allowed to investigate the response of the Peracarid community to variations of the seawater exchange.