Abstract

Mercury (Hg) is considered to be one of the most dangerous global environmental pollutants. The toxicity and bioavailability
of Hg depend on its chemical form, and the greatest hazard is posed by the organomercurial compounds. Hg is introduced into the human body primarily through the consumption of fish and seafood. Despite numerous studies on Hg in marine organisms, there is still a gap in the knowledge on Hg uptake and accumulation by primary producers and animals that occupy a low trophic position, such as benthic invertebrates. The main aim of this study was to investigate the trophodynamics of Hg at the base of the marine food pyramid. The research was carried out in a shallow bay located in the southern Baltic Sea, which is considered a good model of a temperate marine ecosystem. The results showed that the level of Hg in a benthic fauna was strongly affected by the amount and origin of organic matter, both suspended in the water and deposited in bottom sediments. The bioaccumulation of Hg was dependent on the environmental conditions and biomass of the primary producers and consumers. A similar trend occurred in the case of biomagnification of Hg along the trophic chain. The increase in the trophic position of the studied organisms was accompanied by an increase in Hg concentration and an increase in the organic Hg percentage. Despite the differences in the distribution of individual Hg forms in the studied organisms, the bioavailable labile Hg fractions represented more than 90% of total Hg. This indicates an effective transfer of Hg between successive links of the trophic chain and is particularly important because of exposure of Hg to marine organisms but also to humans consuming them.

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