Influence of Life-History Adaptations on the Fidelity of Laboratory Bioassays for the Impact of Heavy Metals (Co2+ and Cr6+) on Tolerance and Population Dynamics of Tisbe holothuriae

To investigate the influence of life-history adaptations on the fidelity of laboratory bioassays, copepods Tisbe holothuriae were collected from two areas (polluted and non-polluted) and maintained in the laboratory under temperatures similar to their wild habitat. The sensitivity of Tisbe increased with increasing temperature. The wild animals from the polluted area were more tolerant to Co2+ and Cr6+ than those from the non-polluted area. Laboratory animals (40 generations after sampling) from the polluted area, were still more tolerant than those from the non-polluted area. These animals also exhibited a similar or increased tolerance, whereas those of the first generation showed a higher sensitivity, compared to the wild ones from the same area. Demography also varied in successive generations after sampling. Laboratory bioassays using T. holothuriae can predict most of its responses in the field, but attention should be paid to adaptations to temperature, pollution and the laboratory environment.