Ecological and Biological studies on some molluscs in Abu Qir Bay, Mediterranean Sea, Egypt

Abstract

Abu Qir Bay was considered as a fertile marine habitat when compared with the other Egyptian Mediterranean coastal waters. The present study was amid to assess the water quality of Abu Qir Bay by measurement the local and seasonal variation of physical and chemical characteristics of the bay water, in addition to determine the concentration of heavy metals (Cd, Cu, Pb and Zn) in water, sediments and bivalve, Donax venustus.As well as, study impact the environmental conditions on the distribution, biodiversity and population dynamics of some molluscs in the investigated area. The obtained data showed that the highest mean values of BOD and COD (3.81 and 15.29 mg/l, respectively) were recorded at station V.While, ammonia and nutrients recorded its highest mean values at stations II and III. Present study showed high value of Cu at station I with a mean value of 9.31 mg/l. Station V recorded maximum concentration of Pb (29.40mg/l) with mean value of 23.32 mg/l. The mean value of Cu in sediment was(17.27 mg/g), station V showed the maximum mean.While the mean value of lead showed that the highest value was at station I (42.97g/g) According to the distribution of the studied metals in the tissues of Donax venustus, it can be stated that Cd, Cu and Zn are lower than the permissible. While Pb recorded higher values which may pointed a problem of lead contamination in Abu Qir Bay. The values of species diversity, density and abundance were seasonally fluctuated. For bivalves, the values of Shannon-Weaver (H), Evenness and Simpsons Indices were high in spring, but declined remarkably in winter, while Margalef's Index had higher value in winter and lowest one in autumn. In gastropods, the values of Shannon-Weaver, Simpsons and Margalef's Indices were higher in winter and lower in autumn, while the values of Pielou’s Index (E) were nearly close with the maximum value in autumn and lowest one in summer.