Effects of dietary n-3 highly unsaturated fatty acids on larval performance in the coconut crab <i>Birgus latro</i> () (Decapoda: Anomura: Coenobitidae)

Abstract The coconut crab Birgus latro () is a terrestrial hermit crab that requires a marine environment for larval development. Populations have declined across its range due to overexploitation and habitat degradation. Artificial propagation techniques have been explored to support breeding programs that release captive-bred juveniles into the wild to aid population recovery. As a basis for developing larval mass-culture methods, we examined the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFAs) on the survival and development of zoeae, and on the survival and emigration behaviors of megalopae (landing, shell carrying, and landing while carrying shells) during the sea-to-land transition. These fatty acids are known to be essential for larval development in some decapod crustaceans. Zoeae were fed zooplankton prey enriched or unenriched with n-3 HUFAs. Although enrichment did not affect the survival of zoeae, it significantly accelerated development to the megalopa stage and promoted earlier expression of emigration behaviors. Enriched diets also increased overall shell-carrying activity. Because shell use reduces desiccation risk and may lower cannibalistic mortality in mass-culture settings, particularly in early-stage megalopae before their shell-wearing behavior is fully developed, n-3 HUFA enrichment may enhance survival. These findings support the use of enriched prey to improve the effectiveness of mass-rearing techniques for B. latro juveniles.