Evaluation of zooplankton community and saprobi index of carp’s culture ponds (Case study: East of Golestan Province-Gonbade Kavous city)

Abstract

The aim of this study was to evaluate of zooplankton communities as bioindicator of water quality and saprobi index at six Chinese carp ponds at East of Golestan province, Gonbade Kavous city. Zooplankton sampling was done monthly during one culture period from June to November 2011. Finally, 27 genus from 4 class were identified. Between these groups, 12 genus belong to Protozoa, 8 genus from Rotatoria, 4 genus from Copepoda and 3 genus from Cladocera were recorded. The highest and lowest frequency percentage were belongs to Rotatoria and Protozoa with 46 and 3 percent, respectively. The results show that, there is no significant differences between saprobi index of six ponds (p>0.05). During the whole period of study, the saprobi index indicated Class ß-mesosaprob as water quality. There was significant general tends of decrease in the saprobi index from the beginning to end of the culture period (p<0.05), its value ranged was 1.52 to 1.70. Also, gradual improvement of water quality observed toward the end of culture period and these reasons are partly a result of natural and management processed such as seasons changes (climate), water exchange (replacement of water) and pause of introduce of fertilizer materials to the ponds.