Investigating the effects of trout farms effluent on riverine macrobenthic fauna based on alpha diversity indices and principal component analysis

Incerease of fish production and necessity of developing this industry by environmental measures show the importance of studing the aquaculture effects. In this stydy, the alpha biodiversity indices for macrobenthic community in response to trout farm effluent located at Gamsiab River were calculated in 2013.
Sampls were collected from four stations at the inflow, outflow, and 500 meter and 1000 meter away from the farm and in three replicates from the middle and sides of the river by surber sampler. After identifying and counting the samples, the different biodiversity indeces including Shanon H', Berger-Parker, Alpha, Casewell, Simpson, Hill-Ho, Margalef and Ept/chir were calculated.
Findings: Results showed that EPT/Chir index decreased in the outflow station in all seasons. Changes in alpha biodivesity indeces showed that some indices, such as Alpaha and Hill indices, in most cases decreased in the outflow station, while some others, such as Margalef richness index, increased. PCA analysis showed the relationship between biodiversity indices and both sampeling units in different stations and seasons and EPT/Chir index. Accordingly, all sampeling units were not related to one index and had stronger relationship wih some of the indices. Therefore, it was concluded that index type affects the study.
Generally, analysis of the biodiversity indices showed that in different seasons and stations and in changing river conditions these indices had meaningful differences with one another, and did not lead to a single result for health situation of ecosystem.