Bioaccumulation of trace metals in marine and estuarine amphipods: evaluation and verification of toxicokinetic models

The suitability of the marine and estuarine gammaridean amphipods Gammarus locustra (Linneaus 1758), Gammarus zaddachi Sexton (1912), and Gammarus salinus Spooner (1947) from the Island of Heligoland and the Weser and Ems estuaries, northwestern Germany, as biomonitors was tested in a toxicokinetic study with the elements Cu, Zn, Pb, Cd, and Hg. The organisms responded with metal uptake upon exposure, and it was possible to estimate parameters of two-compartment or logistic regression models that were statistically different from zero. In most cases, the toxicokinetic models obtained were successfully verified in a second toxicokinetic uptake study for Cu, Zn, Pb, and Cd. Data for Cd were additionally verified with previously reported kinetic parameters. Results for Hg indicate that the organisms tested may not be suitable as biomonitors for this element. The calibration of gammarids as biomonitors was extended in a third toxicokinetic uptake study for Cu and Pb showing a linear increase from the control level to external waterborne metal exposures of 240 µg Cu·L-1 and 60 µg Pb·L-1, while Zn tended to level off above 120 µg·L-1 and Cd above 10 µg·L-1. These figures largely determine the range for which the models may serve as a predictive tool.