Effects of substrate type and locality on species diversity of diatoms in Khormarud River of Azadshahr

Diatoms are microscopic algae ubiquuitous in aquatic ecosystems and strongly influ enced by water quality. The response of a population to changes in an ecosystem is mostly reflect ed by the species composition and their abundance. On the other hand, substrate type can influ ence the responses of diatom assemblages to stresses associated with human activities. Khormarud is the main river of Azadshahr in Golestan province which various human activities occurri ng in the river basin, such as agriculture, Coal mining, fishery and recreation. This study was done to evaluate the effect of different hum an activities and substrate types on species diversity of diatoms in this river. Sampling was d one in two types of substrate, stone and sedime nt and in five sites Preparation, identificat ion and enumeration of diatoms were done in Laboratory.According to results of measurements of the species diversity indices, the hi gh value of species diversity were observed in epipel of site 1 (clean water area), and the lowest value in epilith of site 3 (after fishery activites ). In total epipelic substrates in all sites had high diversity than epilithic substrates.

Diatoms are microscopic algae ubiquuitous in aquatic ecosystems and strongly influ enced by water quality. The response of a population to changes in an ecosystem is mostly reflect ed by the species composition and their abundance. On the other hand, substrate type can influ ence the responses of diatom assemblages to stresses associated with human activities. Khormarud is the main river of Azadshahr in Golestan province which various human activities occurri ng in the river basin, such as agriculture, Coal mining, fishery and recreation. This study was done to evaluate the effect of different hum an activities and substrate types on species diversity of diatoms in this river. Sampling was d one in two types of substrate, stone and sedime nt and in five sites Preparation, identificat ion and enumeration of diatoms were done in Laboratory.According to results of measurements of the species diversity indices, the hi gh value of species diversity were observed in epipel of site 1 (clean water area), and the lowest value in epilith of site 3 (after fishery activites ). In total epipelic substrates in all sites had high diversity than epilithic substrates.