Impacts of Coastal Development Activities On Seagrasses Along The Sudanese Red Sea Coast

Abstract

The study investigated the impacts of coastal development activities along the Sudanese Red Sea coast on the seagrass communities. Six sites were selected: Marsa Bashayer, Marsa Dama Dama, Eastern part of Port Sudan Harbour (Green Area), Northern part of Port Sudan Harbour (Shipyard), Marsa Halout and Dongonab Bay. The study covered the summer and winter seasons in 2003 and 2004. Qualitative and quantitative data were collected at each of the study sites. The seagrass species were identified and their distributions, species diversity, relative percentage cover, shoot density, shoot height and above ground biomass were measured. Some related physical and chemical parameters of the aquatic marine environment were analysed. The heavy metals concentration of Lead, Cadmium, Nickel, and Chromium in the sediment and seagrass tissues, were also analysed. Onshore and offshore development activities at the study sites were recorded. Ten species of seagrass under two families (Hydrochartiaceae and Cymodoceaceae) were encountered. The relative percentage cover of seagrass species ranged between 0 and 100 %. The mean shoot density ranged between 2 and 8050 shoot/m2. The mean shoot height ranged between 1 and 72 cm. and the mean above ground biomass ranged between 8.9 and 985.9 g dry weight/m2. The developmental human activities included trawling, harbours and jetties construction, boats propelling, anchoring, dredging and drilling, 5 dumping of material, discharging of sewage, cooling water and industrial waste and oil spill. Generally, the overall sites showed no major environmental dissimilarities among them except for the water transparency which was significantly lower in sites in the vicinity of high coastal activities area. The mean water oil concentration ranged between 0.01 and 0.3 % and the mean sediment oil concentration ranged between 0.05 and 2.12 %. Marsa Dama Dama site revealed high levels of heavy metal concentration. Some of the developmental activities affected water quality and degraded seagrass beds in some sites. However, the impact varied from site to site. The impacts magnitude ranged between very low at Dongonab Bay and high at the Northern Part of Port Sudan Harbour (Shipyard). The overall evaluation is that the impact is not severe. The study recommended that the conservation and management of seagrass environment should be one of the priorities in the Integrated Coastal Zone Management of Sudan. Policy and legislation formulation were required. Further studies on the seagrass community are urgently needed especially in the fields of taxonomy, ecology, dynamic and utilization. Additional suggestions to conserve and manage the seagrasses habitats were also sited.