Health assessment of fishes from coastal lakes on the east coast of South Africa

MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2018Kosi Bay located on the subtropical east coast of South Africa bordering the south of Mozambique is a unique Ramsar system that is composed of four interconnected, roughly circular lakes that is considered the most pristine system left in KwaZulu-Natal. Kosi Bay is classified as an estuarine wetland which includes mangrove swamps, tidal marshes and deltas that are considered as an important nursing area and feeding source for marine and estuarine fish. According to the Water Research Commission (WRC), a workshop in 2013 indicated there is a general lack of aquatic biodiversity in selected Ramsar sites in South Africa. Limited sampling efforts have been done in Kosi Bay referring to more detailed health investigations. Studies on the fish of Kosi Bay have been done with limited detailed investigations on the fish health. The aim of the study was thus to assess the health on Oreochromis mossambicus, Rhabdosargus sarba and Terapon jarbua. This investigation is important because Kosi Bay is an important nursing and breeding area for fishes and the local community rely on the system to catch these fish. Fish collection surveys took place during the wet and dry seasons, August 2015, December 2015 and February 2016, using hand line and rod and reel. Water quality and sediment samples were also collected in the Kosi Bay and Lake Sibaya systems to determine the metals present in these areas. Only water and sediment samples of Lake Sibaya were collected during this study. The Fish Health Assessment Index protocol (FHAI) was used on the selected fish to determine the health of the fish with a detailed investigation of the abnormalities that may be present in the fish. Metal bioaccumulation, metallothioneins inductions and human consumption hazard of selected fish species in Kosi Bay were investigated. The fish of Kosi Bay was in a relatively good condition with no serious abnormalities present in the fish and the methods used on these surveys were successful with positive resultsWater Research Commission (WRC)Master