Siqwepu, O. (2016). The effect of dietary microalgae on the fatty acid profile, fecundity and population growth of the calanoid copepod Pseudodiaptomus hessei (Mrázek 1884) (Copepoda: Calanoida). M.S. Thesis, University of Fort Hare, South Africa. 64 pp.

427922

Siqwepu, O.

2016

64 pp.

Publication

Available for editors   [request]

This study compares the efficiency of different dietary microalgae on the fatty acid profile, especially the essential fatty acids Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA) of the calanoid copepod Pseudodiaptomus hessei (Mra´zek 1884), a potential live food for finfish larvae in aquaculture. The effect of different dietary microalgae on fecundity and population growth was also investigated. Two mono-algal diets, the Tahitian strain of Isochrysis galbana (Parke) and Rhodomonas salina (Wislouch) and a 50:50 binary diet of the two were fed to copepods. Wild caught copepods were used as a baseline reference point. Copepods fed I. galbana had the highest DHA: EPA ratio and DHA content; although it was not significantly different from those fed the 50:50 binary diet, it significantly differed from those fed R. salina. The EPA content was similar for all three diets. Copepods were collected and preserved in 10 % buffered. The membrane sac was dissolved in a 5 % solution of sodium hypochlorite and gently agitated to dissolve the egg sac. Copepods fed R. salina produced the highest number of eggs per female (34.60 ± 5.97 eggs/female (mean ± standard error)), and were significantly different from those fed I. galbana (22.8 ± 5.44 eggs/female) and the 50:50 binary diet (23.30 ± 6.77 eggs/female). Copepods were counted under a microscope and each stage of development was identified. The highest population was obtained when the copepods were fed I. galbana (709 ± 92.23 individuals/treatment), and was significantly different from R. salina (433 ± 78.08 individuals/treatment) and the 50:50 binary diet (437 ± 40.02 individuals/treatment) populations. The results of this study show that the fatty acid composition of P. hessei can be altered by feeding a variety of dietary microalgae and that the copepod can accumulate fatty acids from their diet, especially DHA and EPA. It is also evident that diet has an effect on fecundity and population development. This makes P. hessei an ideal live food candidate for marine finfish larvae as its nutritional composition and productivity can be manipulated to suit the needs of marine finfish larvae. Based on this study, it is suggested that a 75: 25, I. galbana to R. salina treatment be tested in order to improve both fecundity and population gowth.

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