engleski

Fish farming impact on foraminiferal community: preliminary results from fish farm at Drvenik Island, Adriatic Sea, Croatia

Foraminifera are unicellular marine organisms increasingly used as bioindicators. The fish farming impact on sediment and foraminifera has been studied at fish farm near Drvenik Island. Samples were taken under the cage (DT1, 44.9 m), near the cage margin (DT2, 52.3 m) and on reference station (DTR, 55.7 m). The association at the station DT1 is characterized by Epistominella exigua, Globocassidulina subglobosa, Haynesina germanica. The abundances of listed species are decreasing toward DTR station. Representatives of genera Elphidium, Bulimina and Brizalina have same trend in abundances. Contrary, species Asterigerinata mamilla, Neoconorbina terquemi and genus Cibicides are dominant at DTR and almost absent from DT1 and DT2 samples. Total phosphorus (TP) and total nitrogen (TN) concentrations in the sediments are enhanced at station DT1 and are decreasing gradually from the cage. The abundances of E. exigua, G. subglobosa, H. germanica and genera Elphidium, Bulimina and Brizalina are correlated with TP and TN, indicating their dependence on nutrient input. The absence of A. mamilla, N. terquemi and genus Cibicides at DT1 and DT2 is consequence of degraded community of marine plant Posidonia.

Foraminifera; Marine fish farm; Phosphorus; Nitrogen; Sediment; Adriatic Sea

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