I mpact of some trace metals on bryozoan occurrences, Red Sea coast, Egypt

Abstract

7 9 bryozoan species have been identified from the recent sediments of 5 stations along the Egyptian Red Sea coast. Thirty sediment samples were selected to chemical analysis of Fe, Zn, Pb, Mn, Ni, Co, Cu, and Cd. The analysis indicated that sediments of El-Hamrawen, Hurghada and El Fanader areas recorded the highest concentrations of almost trace metals in comparison with those of Makadi bay and Al Qweh area. Bryozoan colonies showed high frequency and diversity in Makadi bay and Al Qweh area in comparison with El-Hamrawen, Hurghada and El Fanader lagoon. Differences in frequency and diversity of bryozoans among studied areas are attributed to anthropogenic pollutants resulted from diving and snorkeling activities, as well as phosphate dust, especially in El-Hamrawen area. [Key words: Bryozoa, Trace metals, Red Sea coast, Egypt]. Introdu ction Bryozoa is a group of aquatic, sessile invertebrates with circumglobal distribution and includes about 6000 recent species. Although a bryozoan individual is barely visible with the naked eye, all bryozoans form colonies, which are often macroscopic in size and display a variety of beautiful shapes and forms 1 . Recent sediments along the Red sea coast and their gulfs have been studied from sedimentological, geochemical and faunal points of view 2-8 . From studies on bryozoan content along the Red Sea coast 9-18 . Bry ozoans as all marine organisms can be exposed to high metal concentrations resulting of near shore developmental activities, urbanization and over population 19, 20 . Many studies were done on the Red Sea environment, and tourism projects and their impact on coastal zone based on the ecological analysis by several authors 4, 5, 7, 21, 22 . T he main objectives of the present study are to evaluate the levels of trace metals in Recent sediments along the Red Sea coast and an attempt to find a relationship between trace metals in sediments (almost of anthropogenic origin) and bryofaunal occurrences.