Effects of Temperature and Different Feed Uptake on Mercury (Hg) and Cadmium (Cd) Accumulation in Nile Tilapia

Abstract

Climate warming due to increases in atmospherictemperature and heavy metal contamination constitutesa major issue for the aquatic ecosystem. Heavy metal toxicity hinges on an organism’s tolerable limit ofexposure to these elements, and in the aquatic environment, higher temperatures enhances this toxicity infish. The purpose of this study was to investigate the combined effects of higher temperature and differentfeed uptake on Hg and Cd accumulation in Nile tilapia (Oreochromis niloticus). Fish were exposed to asingle concentration of 10 μg/l mercury (Hg) or 100 μg/l cadmium (Cd) for 30 days under 24 °C (roomtemperature) and 32 °C (elevated temperature) conditions in a 7-L aquaria. The feed used in this experimentcomprised pellets, water and pellets, and water and silkworms, in combination with temperature andheavy metal exposure. Results demonstrated Hg and Cd accumulation in flesh, kidney and liver increasedwith increasing temperature. The influence of different uptake mediahas an effect onHg and Cdconcentration levels in fish organs. The order of Hg and Cd accumulation in organs, from the highest levelto the lowest, was kidney, liver and flesh.