The Effect of Density and Temperature on Survival and Fatty Acid Profiles of Copepods (Thermocyclop sp.)

Abstract

Cyclopoid copepods (Thermocyclop sp.) have the nutritional attributes of an ideal diet for fish larvae. However, long-term production and availability of copepods for feeding larval fish in hatcheries remain a challenge. The present study investigated the effect of density and temperature on survival and fatty acid profiles of Thermocyclop sp. at densities: 1 000, 3 000, and 5 000 individuals/L and temperatures: 4 °C, 8 °C, and 12 °C. A log-rank test showed a significant difference between the percentage survival of Thermocyclop sp. at 12 °C and 4 °C (P<0.001) and a significantly higher survival at 1 000 than at 5 000 individuals/L (P<0.001). Generally, saturated fatty acids (SFAs) were dominant compared to monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). For essential fatty acids, no significant differences were observed between storage temperatures on the 7th and 14th days of the experiment. The results demonstrated that at least a 50% survival rate is obtained when these organisms are stored at 12 °C with a density of 1 000 individuals/L for 14 days, with no significant changes in fatty acid profiles. Further studies are necessary to determine the effect of increased storage conditions, perhaps with aeration, on storage time.