Ecological survey on some invertebrates of three stations (Al-Nasir, Al-Shatra, Al-Gharaf), in Al-Gharaf River was conducted. Some chemical and physical factors of the study area have been measured also species diversity, evenness and richness of the invertebrates has been quantified.
58 species of invertebrates were recorded comprised: 3 Annelida, 10 Mollusca, 3 Copepoda, 17 Cladocera, 20 Rotifera, 2 Ostracoda, 3 Crustacean larva. The highest density were recorded in st2 (3201.2 ind/m2 and 5742.22 ind/L) in comparison with st1 (3327 ind/m2 and 423.32 ind/L) and st3 (2369.2 in/m2 and 400.18 ind/L).
Mollusca had higher values of diversity in all stations (1.3, 0.9, 0.85 in st1, st2 and st3 respectively), moreover st1 was higher than that in other stations in ecological indices. Evenness was found to be 0.57, 0.62 for Cladocera and Copepoda in st1 in comparison to st2 (0.53, 0.8) and st3 (0.31, 0.51) respectively. Annelida had a comparable in seasonal values and low in all ecological indices among three stations.
Evenness varied inversely to the temperature. Invertebrate species diversity was positively correlated with chlorophyll a and nitrate, but negative correlated with temperature, salinity , and BOD. |