Investigation of gill mucus cells of Van fish (Alburnus tarichi) during reproductive migration

Lake Van, largest lake of Turkey. It is one of the few lakes in the world. Lake Van is quite different from other aquatic ecosystems due to its physico-chemical properties. Its water is brackish and soda. The lake water has a salinity ratio of 19 ‰ and a pH of 9.8. The salty-soda content of the lake greatly limits biodiversity. Since Van fish is an anadromic fish, it migrates from the extreme conditions of Lake Van to the fresh waters pouring into the lake. In the same way, the reproduction of the fish returned to the lake environment to feed again. In this study, the changes in Van fish gill mucus cells were examined using different histological stains. Mucus cells were located in the primary and secondary coverslips of the gill arches, coverslip tips. Mucus cells were oval and round in the different sizes. Mucus cell areas and densities were observed to change in aquatic areas of different physicochemical properties due to reproductive migration. The intensity of mucus staining was also found to vary in different aquatic locations and gill regions. As a result, it has been clearly demonstrated that mucus cell contents and levels found in Van fish gills vary in different lake freshwater and aquatic environments. In addition, it was determined that mucus cell areas and density varied during reproductive migration. It is thought that the change in mucus cells is caused by salinity, pH, bacterial and parasitic infections encountered in different aquatic environments. These changes in gill mucus cells play an important role in aquatic adaptation of fish.