Phytoplankton community and saprobic pollution index of warm water fishes ponds at East of Golestan Province, Gonbade Kavous city

The aim of this investigation is study of phytoplankton and saprobic index at warm water fishes ponds at East of Golestan province, Gonbade Kavous city. Phytoplankton and ciliate sampling was done monthly during one season culture from June to November 2011. Finally, 39 genuses from 7classes of phytoplankton's and 4 genuses from ciliate group were identified. Although, Between different classes, Chlorophyceae, Cyanophyceae, Bacillariophyceae, Charophyceae, Chrysophyceae, Dinophyceae and Euglenophyceae had highest and lowest frequency percent of phytoplankton community with 23, 21, 20, 14, 11, 6 and 5 percent, respectively. The results showed that, there is no significant differences between saprobic index of different ponds (P>0.05). But there is significant differences between saprobic index value of different months and seasons during season culture (P<0.05).Also, in current research the saprobic index indicated ß-mesosaprob water quality level. There was general tends of decreased in the saprobic index value from the beginning to end of the culture season. Parameters such as biomass increase of grower fishes, increase of introduced chemical fertilizer and manure sedimentation, uneaten fish feed, fishes fecal and no regular exchangeable water resources could be some of the reasons.