Assessment of two-compartment models as predictive tools for the bioaccumulation of trace metals in the amphipod Gammarus oceanicus Segerstråle, 1947 from Grunnfjord (Northern Norway)

Abstract

The objective of the present study is to evaluate the suitability of the eulittoral gammaridean amphipod Gammarus oceanicus Segerstråle, 1947 from Grunnfjord (Northern Norway) as a biomonitor for trace metals Cd, Cr, Pb, Cu, Ni and Zn and to analyse whether the two-compartment model could be used as a predictive tool to assess environmental quality. The focus here is on the adjustment of this model to situations where a linear extrapolation of accumulated metals to increasing external metal exposures is not applicable. The amphipods tested accumulated metals upon exposure and it was possible to estimate significant model parameters of two-compartment models, with the sole exception of Zn. These could be used to predict accumulation of Cd, Cr and Pb in a concentration-dependent uptake study, for Cr directly and regarding simultaneous parameter estimation, for Cd and Pb after adjustment taking into account a non-linear relationship between bioconcentration factors (BCFs) and external metal exposures. The elements Cu and Ni need further evaluation, since linear predictions from the two-compartment models were not applicable, whilst a relationship between kinetic parameters and metal exposures could not be established. Kinetic BCFs at theoretical equilibrium were 80–202 for Cd, 80–112 for Cr, 306 for Cu, 251–520 for Pb and 23 for Ni. A tentative estimation showed the following sequence of sensitivity of G. oceanicus to an increase of soluble metal exposure: 0.6 μg Cd l −1, 0.8 μg Pb l −1, 2.5–2.9 μg Cr l −1, 8.5 μg Cu l −1 and 11 μg Ni l −1. Available information can be used to quantify a measure of agreement or disagreement between bioaccumulation in different amphipods. This can be regarded as an important step in the calibration of biomonitors, which is necessary to assess the potential for bioaccumulation on a large geographical scale.