Spatio-temporal variations of macrobenthic fauna in Lake Nasser khors, Egypt

Spatial and temporal variations of macrobenthic fauna in Lake Nasser khors, were studied at four subsequent seasons during 2013. Khor Tushka West recorded the highest average number (597 Org./m2). It was decreased at khor Kursku (112 Org./m2) and Kalabsha (105 Org./m2) while it reached the lowest at khor Wadi Abyad (65 Org./m2). The highest average number was recorded during spring (447 Org./m2). It decreased during winter (174 Org./m2) and summer (151 Org./m2), then reached the lowest during autumn (107 Org./m2). Annelida, Arthropoda and Mollusca were the most dominant groups in the lake during the study being 72.65%, 26.09% and 1.35%, respectively. The highest number of species (16) was observed at khor Kalabsha. This may be due to its nature of sandy bottom. Biological indices showed high richness values of all the studies khors except khor Tushka West.These low values of indices may be due to the dominance of Annelids species especially, Limnodrilus spp. and Branchiura sowerbyi. There is a positive correlation between these species and total annelids with all physico-chemical parameters. The analysis of variance between the different khors based on the main macrobenthic groups showed a highly significant value (p < 0.001).