Impacts of cage culture of the common carp, Cyprinus carpio Linnaeus 1758, on water quality and phytoplankton communities in Golestan reservoir, north of Iran

Regarding to fish cage culture development in freshwater reservoirs, it is essential to evaluate its environmental impacts. The present study was aimed to evaluate the environmental impacts of common carp, Cyprinus carpio cage culture on water quality and phytoplankton communities of Golestan reservoir, north of Iran. Sampling was monthly conducted from six stations (5, 100, 200, 400, 1000 and 2000 m distance from cages) along this reservoir during April to September, 2016. The water quality parameters and phytoplankton population alterations were sampled at all stations. No significant differences were observed in the environmental variables (except for BOD) among the sampling stations. However, all these variables showed significant differences between the sampling periods. The highest abundances of identified phytoplankton were belonged to Cyanophyta, Bacillariophyta and Chlorophyta respectively in both seasons. Canonical correspondence analysis (CCA) diagrams presented differences in the temporal distribution of sampling units and phytoplankton abundances in both seasons. However, no significant spatial differences were observed. Based on results, we found no consistent environmental alteration caused by cage culture, hence it can be allowed in Golestan reservoir, Iran byclose monitoring its impacts.