Ecological studies on macrobenthic invertebrates in four northern Khors of Lake Nasser (Egypt); Community Structure, Relative Abundance and Diversity.

Abstract

The community structure, abundance and diversity of macrobenthic invertebrates were studied in relation to major physical and chemical characteristics of water and sediment during 2015 in the four northern khors of Lake Nasser (EL-Ramla, Kalabsha, Rahma and Wadi-Abyad). Twenty six macrobenthic invertebrates species belonging to Insecta (15 species), Annelida (5 species), Mollusca (5 species) and Decapoda (1 species) were recorded. The study indicated that the western khors sectors (El-Ramla and Kalabsha) or lying nearby the main stream were higher in species richness and abundance than that of the eastern khors (Rahma and Wadi-Abyad).This may be attributed to their sandy loamy bottom nature that provided with patches of aquatic plants. At the littoral stations, the magnitude of the standing crop of macrobenthic invertebrates showed the highest counts and biomass during winter with an average of 3016 orgs./m2, weighting 9.9 g. fresh wt./m2. In autumn, the standing crop was with an average of 2662 orgs./m2, weighting 19.5 g. fresh wt./m2, when the water temperature fluctuated between18.9 & 25.2°C. On the other hand, the macrobenthic invertebrates at the offshore stations remained low throughout most of the year due to the shortage of suitable substrate. Pearson correlation coefficient showed that the aquatic insects, annelids and molluscs were categorized in relation to water temperature, organic matter and dissolved oxygen, respectively.