Feeding Spectra and Intensity of Freshwater Crab Isolapotamon mindanaoense (Rathbun, 1904) in Lake Sebu, South Cotabato.

The study of food and feeding of crabs is essential to provide the basis for understanding the trophic interaction in aquatic food webs. This paper evaluated the diet intensity and feeding composition of freshwater crab Isolapotamon mindanaoense (Rathbun, 1904) based on sex and size. The physicochemical properties of the water in Hikong Bente (Falls 2) were measured using multiparametric device whereas water samples were collected to assess the plankton composition in the area. The feeding intensity and spectra were assessed analyzed using Index of Relative Importance. Result show that water quality in the area can support aquatic life and are within the quality standard of the DENR. The phytoplankton communities recorded a total of 45 species whereas the zooplankton communities recorded a total of nine species. The feeding intensity of differently-sized (large and small) male and female crabs varied in different months. The stomach contents of 95 crabs consisted of macrophytic remains, fish fragments, insect fragments, and amorphous materials. No difference in food items between sexes and sizes was found. Large crabs appeared to prefer amorphous material, whereas small crabs had higher ingestion of macrophytic remains suggesting their distinct ontogenetic niche. Thus, this study proved that the endemic freshwater crab Isolapotamon mindanaoense (Rathbun, 1904) is omnivorous and detritivorous. All the food items present in their stomach indicates that they were not selective.