Effect of newly isolated high antioxidant diatom on the reproduction and stress tolerance of the marine copepod, Acartia erythraea under crowding stress

Abstract

This study evaluated the effect of antioxidants on a tropical coastal copepod, Acartia erythraea, under crowding stress by using the high-antioxidant, diatom algal strain Thalassiosira weissflogii TRG10-P105 (TW P105) as feed. This newly isolated diatom strain has higher antioxidants than the generic strain Thalassiosira weissflogii (generic TW), which is used as a common feed in copepod culture. Incubation experiments were carried out under various crowding levels (100, 250, 500 and 1000 ind/L). Acartia erythraea, on Day 1, showed comparable and highest egg production and hatching success rate (ca. 68%) at Day 1 with the lowest initial stocking density (100 inds/L) regardless of prey type, indicating both algal strains have similar nutritional potential for egg production under less stressful conditions. However, declining reproduction with increasing initial stocking density through the experimental period was more obvious in copepods with generic TW than in those with TW P105. At initial stocking density of 500–100 inds/L, no egg hatching was observed with generic TW during the latter half of the experiments, while those with TW P105 showed a constantly higher hatching success (30%–80%) during the same period. Overall, A. erythaea fed on TW P105 had much better stress tolerance at high initial stocking density (~1000 inds/L) with 2–3 times higher cumulative number of egg and nauplii compared with generic TW. This result implies that the high-antioxidant diatom algal diet is more effective in ameliorating the adverse effects caused by high density cultivation of copepods than a diet of cogeneric strains.