Ecological Observations on the Macrobenthos of the Nawran Stream, Mosul, Iraq

Abstract

Ecological observations on the macrobenthos of the running stream of Nawran have been made for the past several years. The geography, physical and chemical environmental factors, and the seasonal variation in different populations of macrobenthos living there have been studied with respect to seasonal changes in the environment. The regional community comprises of Dugesia sp., Dendrobaena atheca, Allolobophora, .Eropbdella, Potamon magnum, Rivulogammarus syriacus, Caridina fossarum, Chironomoid sp., Melanoides tuberculata, Melanopsis praemorsa carraruta, and nymphs of may fly and caddis fly. In spring and autumn the fauna is rich in number as well as in diversity. The stream consists of two sections. The upper one has hard substratum and more slope gradient. resulting a fast current of water. The lower section has soft and muddy substratum. The current in this section is slow. Owing to such physical differences, these two sections of the stream support different groups of biota. Biota shows neither upward nor downstream movements but shows attitudinal secession. A statistical analysis has been made between the water temperature and different populations. The degree of association between the water temperature and the population density of different species is measured by the correlation coefficient positive and by significant at 0.05 level.