Density and biomass different species of Amphipoda in the southern of Caspian Sea (Goharbaran region)

This study was carried out in line with the Caspian Sea Central Plateau Water Transmission Program in the southern shores of the Caspian Sea and Goharbaran region in 2013-2014. Sampling was carried out monthly at 8 stations at depths of 5, 10 and 15 meters in 2 transects. The purpose of this study was to investigate the relationships between some physico-chemical parameters of water and TOM (total organic matter), distribution, abundance and biomass of different species of Amphipoda in half-lines, depths, stations and seasons. Overall, one species of Niphargoides caspius from the Gammaridae and four species of Stenogammarus similis, Stenogammaus macrorus, Stenogammarus carausuii and Stenogammarus compenus of Pontogammaridae were identified. A total of 15118 individuals of the benthic organisms were counted, in which, S. compresus and N. caspius with 68 and 2 percentages, respectively. Overall, the mean (± standard error) density and biomass of benthic organisms during the period were 128±14.08 ind.m-2 and 0.15±0.01 g.m-2, respectively. According to Spearman test, density of S. carausuii, S. macrorus and S. similis was significantly correlated with sedimentation (sand) (p<0.01). Multivariate cluster analysis based on Spearmanchr('39')s correlation coefficient on the relationship between density and biomass of different species of Amphipoda with some environmental parameters, grain size and total organic matter (TOM) of bed sediments showed that the members of this group belonged to a sand bed and dissolved oxygen are more strongly correlated in which could be due to ecological origin of Amphipoda groups.