Bioenergetic calculation of mercury accumulation in fish

A numerical model was developed for the bioaccumulation of mercury (Hg) in fish. The model is based on the bioenergetic calculation of fish growth, food consumption, respiration, specific dynamic action and waste losses (egestion/excretion) using the program of Hewett and Johnson (1992). Based on the predation and food results obtained, the accumulation of Hg in fish is calculated taking into account the concentrations of methyl mercury (MeHg) in food and water, its intake and accumulation from food and from water, and the removal of Hg from the body. Some species at various levels of food web are considered in the multistep model applications. The model is used to compute the changes of Hg contents in perch (as prey) and pike (as predator) caused by the release of Hg from the bottom sediments when the Kokemäki River in Western Finland was dredged. The model results were not far from the observed results even though the forcing conditions had been described only roughly.