Effects of salinity, cold storage and enrichment on the calanoid copepod Gladioferens imparipes

Abstract

Intensive culture techniques have been developed for the calanoid copepod Gladioferens imparipes. Despite reliable, long-term production of nauplii from these cultures, further improvements are required to maximise the number and nutritional content of nauplii available for feeding to larval fish. The effects of salinity on copepod production and prolonged algal enrichment on nutritional content of nauplii is shown. Use of cold storage for accumulating large numbers of nauplii and storing adults with minimum maintenance is evaluated. The size range of G. imparipes life history stages, particularly early nauplii, is determined. Maximum copepod production was obtained in salinities of 18–27‰. Fatty acid content of nauplii increased with prolonged enrichment. Copepod survival was poor at 4°C. At 8°C, nauplius survival was 99% after 12 days and adult survival was 90% and 68% after 21 and 42 days, respectively. Early nauplii were 67 μm in width, similar to nauplii used to rear larvae with small gapes at first feeding. Implications of these results to the use of G. imparipes as food for fish larvae is discussed.