Benthic fauna and microbial communities as a bio-indicator for the characteristics of the marine environment in the Suez Bay , Red Sea , Egypt.

Abstract

Environmental variables were measured with benthic fauna and bacterial organisms to assess water quality and sediments in the Suez Bay. A total of 62 species belonging to five taxonomic groups (Polychaeta, Mollusca, Crustacea, Echinodermata and Urochordata) were collected from benthic fauna at thirteen stations extending from Summer (2019) to Winter (2020) along the intertidal zone of the Suez Bay. Polychaeta accounted for 38.71% and 47.3% of the total number of species and individuals, respectively. While, Urochordata represented by one species and 50 indivi./m². In the Suez Bay, bacterial populations are present in the water with an annual density of 21598 cfu / 100ml with an average of 1661.4. At the same time they are present in the sediments with a numerical density of 16331 cfu / g with an average of 1256.23. Dissolved oxygen (DO), Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of tested samples ranged between 3.2 - 6.45 mgO2/l ; 0.995 -2.298 mg/l ; 2.298- 4.69 mg/l , respectively. This investigations revealed that, with the exception of the alien ; dominant and adherent rocks species (Spirobranchus kraussii and Brachidontes pharaonis), microbial components tend to increase their dominance, while bottom organisms were reduced during the entire study period. In addition ,this study indicated that there is a direct relationship with both salinity, dissolved oxygen and macro-benthic invertebrates, and at the same time there is an inverse relationship between them and bacterial counts, indicating thus a predominant effect of anthropogenic activities in the coastal area of Suez Bay.