Invasive Species Compendium

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Abstract

Influence of the different feeding schedule of food organisms for larval swimming crab Portunus trituberculatus.

Abstract

An experiment was conducted to investigate a suitable feeding schedule for different larval stages of the swimming crab, P. trituberculatus when fed on rotifer and/or Artemia nauplii enriched with n-3 highly unsaturated fatty acids (n-3 HUFA) at zoea 3 and zoea 4 stages. Two feeding experiments were carried out in 1-litre beakers with duplicate lots, each holding 30 larvae. The moulting rate and the inter-moult period in days to reach each larval stage were measured. The data were compared with n-3 HUFA contents in live foods (rotifer and Artemia). When the zoea 3 stage larval crabs were introduced to the live foods containing n-3 HUFA, especially Artemia, the moulting rate of the megalopa and the inter-moult period were much improved compared with the zoea 3 stage fed unenriched live foods or when live foods were initiated at the latter zoea 4 stage. It was also found that the incorporation of n-3 HUFA content in Artemia (2.7%) was higher than that in rotifer (1.6%), even though both were enriched with the same amount of emulsified oil (EPA28G: 25.0% eicosapentaenoic acid and 10.1% docosahexaenoic acid). Therefore, the enriched Artemia appears to be a better vehicle for fatty acid delivery to the crab larvae. The results suggest that larval crab should be fed Artemia containing n-3 HUFA from the zoea 3 stage in order to get a high survival rate for the first swimming crab.