The harpacticoid copepod Tisbe holothuriae is resistant to the insidious effects of polyunsaturated aldehyde-producing diatoms

Numerous species of diatoms liberate oxylipins including polyunsaturated aldehydes (PUAs) in response to cellular damage such as may occur during grazing. PUAs are cyto- and genotoxic and negatively disrupt reproductive processes in copepods, their principal grazers, although experimental evidence would suggest that the grazer response may be species specific. The reproduction of the benthic harpacticoid copepod Tisbe holothuriae was compared over two generations. Copepods were reared using four diet treatments: PUA-producing diatom strains Skeletonema marinoi (Adriatic Sea Isolate FE6) and Melosira nummuloides (CCAP 1048/6); and non-PUA-producing diatom strains Phaeodactylum tricornutum (CCAP 1052/A) and S. marinoi (Seasalter (Walney) Ltd). Life tables were generated for each treatment using measured reproductive parameters and the net reproductive rate (R0) calculated. No significant differences were observed between the individual reproductive parameters of T. holothuriae fed PUA-producing diatoms compared to those fed non-PUA-producing diatoms although diets of P. tricornutum resulted in some decreases in individual reproductive parameters in the second generation. There were no significant differences in the R0 values between the four tested diets. These observations indicate that T. holothuriae exhibits a tolerance of known PUA-producing diatom diets that has not been similarly demonstrated in pelagic calanoid copepods. Harpacticoid copepods may have a greater capacity to detoxify diatom oxylipins than their planktonic calanoid counterparts.

► Tisbe holothuriae is resistant to the toxic effects of polyunsaturated aldehydes. ► Diatom diets did not affect individual reproductive parameters over two generations. ► Phaeodactylum tricornutum reduced reproductive output in the second generation. ► Harpacticoids may detoxify algae toxins more effectively than pelagic calanoids.