Growth, egg production and hatching success of Acartia tonsa cultured at high densities

Acartia tonsa is a calanoid copepod with high potential as live feed for marine aquaculture. However, its usage remains limited at an industrial scale, with cost effective production being conditional on successful culture at high density. The present study took an integrated approach to provide further insight on the effects of A. tonsa stocking density on copepod growth and adult reproduction, specifically egg production and egg hatching success. The effect of stocking density was studied by following the growth and survival of A. tonsa copepods, from egg hatching to maturity, on cultures initially stocked with 250, 400,1000, 3000 and 6000 copepods l(-1). Additionally, the effects of high-density rearing, of adults kept at 100, 250, 500 and 2500 copepods l(-1), on egg production and hatching success were also evaluated over a 5-day period. Higher stocking densities were shown to have no unfavourable effect on copepod growth, though mortality significantly increased with density, from <= 2.5% d(-1) at densities of <= 1000 copepods l(-1) to 3.5-4.0% d(-1) at 3000-6000 copepods l(-1). Individual egg production decreased with increasing stocking densities, from 28 eggs female(-1) d(-1) at 100 copepods l(-1) to 7 eggs female(-1) d(-1) at 2500 copepods l(-1). However, total yield still increased with stocking density, with the cumulative egg production at 2500 copepods l(-1) being 4 times the production at lower densities (from 100 to 500 copepods l(-1)). Though adult rearing density had no effect on 96-h hatching rate (60 to 69%), a density-dependent late hatching was observed on eggs produced by adults grown in dense cultures (500-2500 copepods l(-1)), with 48-h hatching success significantly decreasing with increasing densities (from 37% to 1%). In spite of the negative effect of stocking density on survival during growth and egg production, the magnitude of these effects does not compromise the use of high density cultures. Future research should focus on the improvement of production systems, as the ability to rear calanoid copepod species at large scale would present a major advancement in larviculture of marine fish species. Supporting statement: The present research focused on the effects of A. tonsa stocking density on copepod growth and adult reproduction, specifically egg production and egg hatching success. This is the first study on A. tonsa high-density culture from copepod growth to egg production and hatching. It further provides new insight on the viability of using high-density cultures for egg production and its impact on hatching success, essential for the commercial production of this species (C) 2016 Published by Elsevier B.V.