Trophic transfer and biomagnification potential of contaminants in aquatic ecosystems.

This review summarizes information obtained from published literature to determine to what degree biomagnification of organic compounds and metals occurs in freshwater and marine food webs. This review was conducted by: (1) examining data from studies conducted in laboratory experiments to establish body burden ratios between trophic levels (trophic transfer coefficients; TTCs); (2) comparing laboratory-derived TTCs with data obtained from field studies; and (3) comparing biomagnification predictions described by published aquatic food-web models with data obtained in this review. It was determined that: (1) the majority of chemicals evaluated (both organic and metals) do not biomagnify in aquatic food webs; (2) for many of the compounds examined, considerable trophic transfer does occur in aquatic food webs; (3) DDT, DDE, PCBs, toxaphene, methyl mercury, total mercury, and arsenic have the potential to biomagnify in aquatic systems; (4) the lipid fraction of receptors directly influences biomagnification of lipophilic compounds; (5) the food web model reviewed provided similar estimates for most of the organic compounds examined (log Kow values between 5 and 7), with model predictions falling within the range of values of all compounds except dieldrin; (6) for many organic compounds, lack of information precludes assessing the relative importance of biomagnification for these contaminants; and (7) even those compounds for which evidence for biomagnification is strongest show considerable variability and uncertainty regarding the magnitude and existence of food-web biomagnification in aquatic systems.

Lethality of a suspended clay to a diverse selection of marine and estuarine macrofauna.

In this investigation, an evaluation was made of the lethality of suspended clay mineral texturally representative of the sediment-size fraction with which contaminants are most commonly associated. The study involved a phylogenetically diverse selection of marine and estuarine macrofauna. The time-concentration mortality response of 16 species of fish and invertebrates indicated widely differing sensitivities to high concentrations of clay suspended in the water. Organisms restricted to muddy bottoms were found to be very insensitive to high suspended clay concentrations. However, some open water fish, fouling organisms, and sandy bottom epifauna were found to be relatively sensitive. Tolerant species were also identified from these groups.