Heavy metals, with their persistence and toxic nature affecting marine organisms as well as their trophic bioaccumulation along food chain, are one of the major focus in coastal environmental pollution. Metal accumulate in marine fishes through two major pathways: the particulate phase (food ingestion) and dissolved phase. Water quality criteria should be set by considering both the bioavailability of metals to marine organisms and their uptake pathways. And, a bioenergetic-based kinetic model has been developed to assess the exposure pathway of metal accumulation in marine organisms. Without measuring too many parameters from the environment, the trophic transfer factor(TTF) can be predicted based on the measurements of metal AE and efflux rate, fish’s ingestion activity and growth rat...[ Read more ]

Heavy metals, with their persistence and toxic nature affecting marine organisms as well as their trophic bioaccumulation along food chain, are one of the major focus in coastal environmental pollution. Metal accumulate in marine fishes through two major pathways: the particulate phase (food ingestion) and dissolved phase. Water quality criteria should be set by considering both the bioavailability of metals to marine organisms and their uptake pathways. And, a bioenergetic-based kinetic model has been developed to assess the exposure pathway of metal accumulation in marine organisms. Without measuring too many parameters from the environment, the trophic transfer factor(TTF) can be predicted based on the measurements of metal AE and efflux rate, fish’s ingestion activity and growth rate. In this study, we have quantified these important physiological parameters and further incorporated into the model so as to predict the metal bioavailability in marine fishes.

Both intertidal carnivorous mudskipper (Periophthalmus cantonensis) and pelagic herbivorous rabbitfish (Siganus canaliculatus) were able to accumulate metals from particulate as well as dissolved phase. Particulate phase represents the major route of metal uptake for fish. Gut passage time in both fishes was found to be positively correlated to the metal AE determined in our study. Metal influx rate increases when ambient salinity decreases. Metal uptake from dissolved phase increase linearly with the increase in dissolved metal concentration. Metal concentration in food will increase the body burden but it had no significant effect on metal AE. Both nutrient level and starvation had posed some effect on metal AE in fish. Furthermore, the calculated TTF is ≥ 1 for Se and Zn at high feeding rate. Thus, our study indicates that Se and Zn may have been biomagnified in the higher trophic marine fishes. Moreover, metal accumulated in fish were being distributed in different parts of the body specific to metal species. These results are significantly important for determining the relative importance of metal uptake in marine fishes from the two exposure pathways and thus help in establishing reliable water quality criteria.