Inhibition of Diatom Diet on the Reproduction of Paracalanus parvus

In this paper the effects of food type on reproduction of copepods were investigated by feeding the planktonic copepod Paracalanus parvus in laboratory. Paracalanus parvus reared on diatom Chaetoceros muelleri (CM) had lower egg production (0.31 plusmn 0.05 eggs female -1 d -1 ) and female longevity. In contrast, the flagellate Isochrysis galbana (IA) supported relatively high egg production (6.98 plusmn 1.02 eggs female -1 d -1 ) and female longevity. The analysis of egestion indicated that the inhibition of CM was mainly due to deterrence. In filtered seawater, CM had lower hatching success than IA, indicating that the difference in hatching of Paracalanus parvus were associated with maternal effect. Among all treatments, hatching success in filtered seawater were significantly higher than that in algal suspension, indicating that probably not only diatom but also other phytoplankton could release inhibitory agents at high concentration.