Two-generational effects of contaminants in D. magna. Effects of offspring quality.

Abstract

The authors aim to set up a protocol to perform a two-generational ring test using the existing guidelines for the Daphnia magna reproduction test. It is well known in ecology that size and quality of offspring varies across the first clutches in D. magna and that certain chemicals affect offspring quality. Therefore, the origin of the second generation is an important factor to consider. Two-generational effects across first, second and third clutches were evaluated using 4-nonylphenol; across first and third clutches using tributyltin and across the third clutch using piperonyl butoxide. The compound showing the greatest aggravation of toxic effects between the parental and second generations was piperonyl butoxide followed by 4-nonylphenol, while inter-generational effects of tributyltin TBT varied across experiments. The studied chemicals affected the quantity and quality of the offspring produced by exposed females of the parental generation, being those effects greater in third clutch neonates. Therefore, when third clutch offspring were further exposed they turn out to be more sensitivity than the parental generation. These results are in line with those obtained in multigenerational studies in mammalian tests, which show that in many cases effects on the second generation can be predicted by evaluating the quality of the offspring produced.