The effect of the toxic dinoflagellate on the fitness of the calanoid copepod .

Inshore and offshore waters of the Gulf of Maine (USA) have spring/summer harmful algal blooms (HABs) of the toxic dinoflagellate , which is responsible for paralytic shellfish poisoning (PSP) in humans. The calanoid copepod co-occurs with during the seasonal blooms. At that time, population abundances are high, dominated by immature copepods preparing for diapause, and by actively-reproducing adults. High survival has been reported for copepods exposed to toxic , but little is known about possible sublethal effects. In this study, adult females were fed either a control diet of non-toxic spp. or one of two diets containing either low dose (LD) or high dose (HD) levels (50 and 200 cells mL, respectively) of toxic for a total of 7 days in two independent experiments. As expected, ingestion of the dinoflagellate had no effect on copepod survival and grazing activity. However, significant reductions of egg production and egg viability were observed in females fed on either experimental diet. After the 7-day experiment, total nauplius production by females on the LD and HD diets was reduced by 35% to 75% compared to the control females. These results suggest that blooms of in the Gulf of Maine may be an environmental challenge for populations, with a potential negative effect on copepod recruitment.