Corsica Island is a sub-basin of the Northwestern Mediterranean Sea, with hydrological features typical of both oligotrophic systems and eutrophic coastal zones. Phytoplankton assemblages in two coastal ecosystems of Corsica (the deep Bay of Calvi and the shallow littoral of Bastia) show contrasting patterns over a one-year cycle. In order to determine what drives these variations, seasonal changes in littoral phytoplankton are considered together with environmental parameters. Our methodology combined a survey of the physico-chemical structure of the subsurface water with a characterization of the phytoplankton community structure. Sampling provided a detailed record of the seasonal changes and successions that occur in these two areas. Results showed that the two sampled stations presented different phytoplankton abundance and distribution patterns, notably during the winter–spring bloom period. Successions in pico-, nano-, and microphytoplankton communities appeared mainly driven by differences in the ability to acquire nutrients, and in community-specific growth rates. Phytoplankton structure and dynamics are discussed in relation to available data on the Northwestern Mediterranean Sea. These results confirm that integrated monitoring of coastal areas is a requisite for gaining a proper understanding of marine ecosystems.

The parasitofauna of 148 salmonids has been analyzed. Three host species have been recorded in the insular hydrographic network: the brown trout, Salmo trutta, the rainbow trout, Oncorhynchus mykiss and the brook trout, Salvelinus fontinalis. In order to characterize the parasites in these salmonids a Factorial Analysis of Correspondances (FCA) has been used. Four parasites species have been found in Salmo trutta, one in Oncorhynchus mykiss and one in Salvehnus fontinalis. Data on parasites species composition, and infection levels, would help improve in the biodiversity conservation by preventing the fusion of autochtonous stocks of Salmo trutta (Corsican and Mediterranean) and the introduced stocks (Atlantic) in only one stock.