GÜMÜŞ BALIĞI (ATHERINA BOYERI, RISSO 1810)’NIN DENİZ VE İÇSU POPULASYONLARININ BÜYÜME ÖZELLİKLERİ İLE SOLUNGAÇ VE BÖBREK HİSTOLOJİLERİNİN KARŞILAŞTIRILMASI

Abstract

The sand smelt, Atherina boyeri is a short-lived euryhaline fish inhabits mainly coastal and estuarine waters. It has also been illegally translocated into inland freshwater lakes and reservoirs for fisheries purpose. In Turkey, many freshwater reservoirs isolated from the sea have been rapidly invaded by A. boyeri especially during the last decades. The aim of the present study was to compare the growth performance and the histological differentiations in osmoregulatory organs such as gill and kidney that were related to the low salinity conditions of translocated inland water populations with natural marine populations of sand smelt. Marine populations of sand smelt were obtained from Mediterranean and Black Sea, Sea of Marmara, Aegean Sea and Lake Köyceğiz lagoon (Muğla). Translocated inland populations were obtained from two reservoirs; Aslantaş (Osmaniye) and Hirfanlı Dam (Ankara), and two freshwater lakes; Eğirdir and İznik. The total length and the body weight were ranged between 21.25-142.96 mm and 0.04-19.52 g, in sea populations; 27.93-97.03 mm and 0.12-6.60 g, in the lagoon; 23.87-115.65 mm and 0.08-10.94 g, in the inland populations. The difference between the b value of sea and inland populations estimated from length-weight relationships were not significant. The growth of inland water and lagoon populations showed positive allometry. The k values of the von Bertalanffy equation were ranged between 0.16-0.55 in sea populations and 0.23-0.49 in the inland populations, whereas it was 0.29 in lagoon population. The mean value of condition factor ranged between 0.25-0.85, in marine populations; 0.31-1.02, in the lagoon; and 0.21-0.97 in inland populations. The results revealed that sand smelt exhibited similar growth performance in marine and inland waters. The number and size of the chloride cells in gills and glomeruli were considerably high in inland water samples. This change in chloride cells of both gills and kidneys may have facilitated the adaptation of sand smelt to different environments with changing salinity. Despite the fact that the energy budget changes with changing osmoregulation effort in inland water populations, growth performance seem to not be affected in this study.