Feeding ecology of Portunus pelagicus (Linnaeus, 1758) (Brachyura, Portunidae) in the southern Gulf of Thailand: influences of habitat, season, size class, shell stage and ovigerous condition

Abstract

The aim of this study is to simultaneously evaluate the impact of ecological and biological conditions on feeding habits of Portunus pelagicus (Linnaeus, 1758). Samples were collected from May 2013 to September 2014 using gill nets. Four moulting stages, three berried stages and four size classes were distinguished in the material collected. It was found that P. pelagicus is omnivorous, feeding on a wide range of benthic invertebrates, scavenging on dead pelagic animal remains, and ingesting significant amounts of plant material. Seasonally, no difference in the stomach fullness index was observed (), but there was a difference in the average number of items (). Both stomach fullness and average number of food items differed between habitats (). Results from multivariate analyses indicated that the diets of P. pelagicus did not change with season but did vary with habitat. Crabs with different biological conditions ingested different food packages. This finding helps in understanding how P. pelagicus copes with different ecological and biological conditions in ingesting its preferred food (under the circumstances).