Effect of Amphipods (Grandierella megnae) Density on the Growth and Survival Rate of Mangrove Crab (Scylla tranquebarica)

Abstract

This study aims to determine the effect of amphipod density on the growth, survival and molting of mangrove crabs (Scylla tranquebarica).The research was conducted in the Installation of Tiger Shrimp Hatchery (ITSH), located Lawallu Village, Soppeng Riaja District, Barru Regency, South Sulawesi, from May to June 2022.  There was 45 mangrove crabs, with an average weight of 0.04 ± 0.005 g and a carapace width of 5.4 ± 0.1 mm which were obtained from local hatcheries. The maintenance container is a glass jar containing 0.5 liters of water, each jar is filled with one crablet. The treatments tested were differences in amphipods density, namely: A) 20 ind/0.5 L, B) 30 ind/0.5 L, C) 40 ind/0.5 L, feeding frequency is once a day for first 10 days and twice a day at 8:00 AM and 5:00 PM for next 20 days. Parameters observed were growth weight (GW) and growth carapace width (GC), specific growth rate-weight (SGR-W) and specific growth carapace- width (SGR-C), survival rate (SR) and number of molting (NM). Using a completely randomized design with three treatments and three replications, each replication consisted of 5 crabs. Data were analyzed for variance and Duncan's further test, physical and chemical parameters of water were analyzed descriptively. The results showed that amphipod density had an effect on GW, GC, SGR-W and SGR-C, but had no effect on SR and NM. Amphipod densities of 20 - 40 ind/0.5 L produced good survival and a large number of molting, but amphipod densities of 30 ind/0.5 L were more efficient for the growth of mangrove crabs.