Feeding ecology and prey selection of sand smelt, Atherina boyeri Risso, 1810 in Eğirdir Lake (southern Anatolia, Turkey)

Abstract

Feeding ecology and prey selection of sand smelt (Atherina boyeri, Risso, 1810) were investigated by taking monthly samples (January to December 2010) at four stations of Lake Eğirdir, (Turkey) using gill nets (mesh sizes 10–100 mm) and purse-seines (mesh size 6 mm). A total of 49 out of 612 analysed stomachs were empty (8.01%); stomach contents included eight major prey categories: zooplankton, phytoplankton, Arachnida, Arthropoda, Insecta, fishes as well as unidentified organisms and remains. Dominant prey items included cladocerans (Bosmina longirostris [% N = 67.92], Alona quadrangularis [% N = 5.06]), copepods (Nitokra hibernica [% N = 9.30], Mesocyclops leuckarti [% N = 3.35]), and arthropoda (Corophium curvispinum [% N = 3.46]). The importance of Insecta, Arthropoda, fishes, and unidentified eggs increased in the diet with increasing size of the sand smelt, whereas the contribution of Cladocera and Copepoda decreased. Sand smelt strongly preferred B. longirostris (selectivity index V = 0.639, χ2 = 81.689, p < .01), N. hibernica (V = 0.205, χ2 = 8.429, p < .01), and A. quadrangularis (V = 0.159, χ2 = 5.039, p < .01) despite their low abundance in the environment. Atherina boyeri (V = −0.699, χ2 = 97.812, p < .01), Aphanius anatoliae (V = −0.328, χ2 = 21.463, p < .01), Insecta (V = −0.229, χ2 = 10.497, p < .01), and Keratella cochlearis (V = −0.265, χ2 = 14.009, p < .01) were the most abundant prey in the environment, however they were negatively selected by sand smelt. Knipowitschia caucasica, Asplanchna priodonta, Trichocerca sp., Lecane sp., and Acaridae also inhabit the lake, but were not found in the sand smelt food items. Cladocerans dominated during autumn and winter, arthropods, copepods, rotifers and phytoplankton in spring, whereas Insecta and fishes were dominant in summer.