Case study of marine pollution in Teluk Bahang, Penang, Malaysia

Teluk Bahang is a small fishing village located in the north-western of Penang Island, Malaysia. It has several attractions which include forest reserved park, ecotourism sites, theme parks and famous for its aquaculture activities. On 18th April 2019, fish farmers in Teluk Bahang experienced mass mortality of cultured fishes, namely groupers, barramundi, golden and red snappers due to a sudden change in water quality. Hence, this study was conducted to discuss marine pollution that occurred in Teluk Bahang that had caused the death of tonnes cultured fishes. Water samples were collected at the fish cage to investigate the water quality (physical and chemical parameters), heavy metals content, cell density and phytoplankton composition for determination of algal bloom that might be the cause of this crisis. Water samples were collected three times on 19th April 2019, 8th May 2019 and 26th May 2019. The results for physical and chemical parameters (pH, salinity, surface temperature, nitrate and phosphate) were all within the permissible limit according to Malaysia Marine Water Quality Class 2 (for aquaculture and recreation). Almost no harmful dinoflagellate species were detected in the water samples which indicated that phytoplankton did not cause a direct effect on the fish mortality. The concentration of heavy metals namely Cu, Cd, Ni, Fe, As and Hg in water samples were measured by atomic absorption spectroscopy (AAS). Results showed no detection of As and Hg concentration. The concentration of Cd, Cu and Fe in water ranged from 0.058-0.065ppm, 0.057-0.077ppm and Fe 0.326-0.389ppm respectively. These levels exceeded 20-100 times from the permissible limit. Ni concentration detected at 0.472-0.513ppm which was 990 times exceeded the permissible levels. These results indicated that metal pollution occurred in the marine water of Teluk Bahang and the possibility that the area may no longer be suitable for aquaculture or recreational purposes.