Status of Mercury Concentration in Mudskipper Goby (Periophthalmussobrinus) Found in Zanzibar Intertidal Areas
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THE STATE UNIVERSITY OF ZANZIBAR
Marine pollution by heavy metals is a worldwide issue of concern today. Improper waste disposal in Zanzibar, especially electronic waste that releases different chemicals such as Arsenic, Chromium, lead and mercury to the environment, together with agricultural activities, tanning and municipal waste which contain harmful chemicals poses a threat to aquatic environment. The present study aimed to determine the concentration of total mercury concentration in goby fish (Periophthalmussobrinus) tissues found in Zanzibar Islands. A total of 75 fish were collected during low tides at four sites found in Unguja Island which are Bumbwini, Kilimani, Kinazini and Malindi. Twenty fish were captured per site, except Kilimani intertidal area where only fifteen fish were collected due to weather conditions. The collected fish were first stored at – 20 0C refrigerator and then dissected and lyophilised (freeze-dried) by using Labconco Freezone 2.5 L freeze drier for sampling analysis. The total mercury concentration of fish tissues was analysed by using DMA-80 Direct Mercury Analyser with the DORM 4 certified reference material. Data showed that the total mercury concentration in fish samples did not exceed the standard set by of 0.5 mg/kg dry weight of methylmercury concentration. However, three goby fish collected at Bumbwini intertidal area were found to have total mercury concentration which range from to 0.224 -0.2811(mg/kg) which exceed the 0.2 mg/kg allowable limit of total mercury concentration for vulnerable groups (frequent fish consumers, pregnant women, and children under 15 years old).The correlation between total mercury concentration with fish weight and length was evaluated by using Pearson correlation model. Comparisons yielding probability values of less than 0.01 were considered to demonstrate the correlation. Overall, there was a positive correlation between fish length and total mercury concentration but not significant; except for the fish collected at Kilimani intertidal area, which showed significant positive correlation between fish length and total mercury concentration (correlation= 0.932, p =0.000). However, the fish collected at Malindi intertidal area shows negative significant correlation between fish length and total mercury concentration(correlation = - 0.653, p =0.002).Generally these results suggest that the goby fish from Bumbwini, Kilimani, Kinazini and Malindi are safe for human consumption but this is an alarm of mercury contamination to the coastal marine ecosystem of Zanzibar.
Marine pollution by heavy metals is a worldwide issue of concern today. Improper waste disposal in Zanzibar, especially electronic waste that releases different chemicals.
Marine pollution, Mercury concentration