Abstract

In this study, the phytoplankton composition and some water quality parameters of cultured sea bass (Dicentrarchus labrax, L., 1758) earthen ponds were investigated in Muğla Province, Turkey. Sea bass which production significantly increased since the 1980s, is accepted as one of the popular species in the Mediterranean region. Samples were collected from the fish farm when algal blooms are observed in May 2017, from 6 sampling points, including the main drainage, clean water, and 4 earthen ponds. In total 31 taxa belonging to 7 divisions as Bacillariophyta (13), Charophyta (1), Chlorophyta (7), Cryptophyta (2), Cyanobacteria (3), Euglenozoa (4), and Ochrophyta (1) of phytoplankton were determined. Recorded species of the phytoplankton indicated organic pollution at the studied earthen ponds. Excessive algal blooms, particularly caused by blue-green algae, pose a great threat to all fish farm organisms by causing massive fish deaths in aquaculture ponds. The toxin-producing Cyanobacteria Microcystis aeruginosa (Kütz.) Kützing and Merismopedia glauca (Ehr.) Kützing were found often in water samples. Since pond management is essential for a productive fish farm obtained results indicated that the first step to enhancing good quality products in the aquaculture sector should have the sustainable monitoring of phytoplankton by farmers and adequate supplying water.