Feeding Choice and the Fate of Organic Materials Consumed by Sesarma Crabs Perisesarma bidens (De Haan) When Offered Different Diets

The feeding preference of the sesarmid crab Perisesarma bidens was investigated when offered different diets: Enteromorpha intestinalis (algae), Kandelia obovata leaves, and propagules. Nutritional value of food, its assimilation, and fates were evaluated using a combination approach of the fatty acids (FAs) and C/N ratios. When offered a mixed diet, male crabs preferred algae than leaves and/or propagules, while a female preference was equally for leaves and algae but less than propagules. The nutritional value of algae was higher as indicated by low C : N ratios and high ω3/ω6 ratios than leaves and propagules. FAs comparison of tissues and faeces indicated that crabs efficiently assimilate essential fatty acids (EFAs) from a given diet in the order of algae greater than leaves and propagules. Despite of sesarmid crabs being a mangrove leaf-eater, E. intestinalis can potentially be important source of nitrogen supplement for P. bidens under mangrove forests.