Diet and Feeding Habits of Arboreal Crab Labuanium politum from Samunsam Wildlife Sanctuary, Sarawak

• Main Authors: Siti Akmar Khadijah, Ab Rahim, Nur Amirah, Mohamad Alwie, Akma Iddin, Masini
• Format: Book Chapter
• Language: English
• Published: UNIMAS Publisher 2024
• Subjects: SH Aquaculture. Fisheries. Angling
• Online Access: http://ir.unimas.my/id/eprint/45543/1/Diet%20and%20Feeding.pdf; http://ir.unimas.my/id/eprint/45543/

Labuanium politum (Family Sesarmidae) is an arboreal crab that can be found in the nipa forest of mangrove ecosystem but information on its feeding ecology in a protected area is still lacking. Furthermore, Samunsam Wildlife Sanctuary (SWS) is partly disturbed by the construction of Pan-Borneo Highway which may alter food availability for L. politum. Therefore, it is important to investigate the diet and feeding habits of L. politum in the sanctuary nipa forest. Crab samples were randomly collected at night time (9-11 August 2018) in order to match their active foraging time. The stomach fullness of the crabs was scored and diet composition of L. politum was evaluated by sorting the stomach contents into five categories. A total of 41 stomach contents were analysed from crabs with carapace width ranging from 8.32 to 34.00 mm. Results of diet composition showed that L. politum consumes equally two major components i.e. plant (92.68%) and sediment materials (92.68%); and followed by small quantity of animal materials (26.73%) and diatom (9.76%). These indicate that L. politum is an herbivore-biased omnivore. Weighted Resultant Index (Rw) showed that all food materials were consumed more frequent but in small amount; and both plant and sediment materials were the most important food items as the recorded Rw values are closer to 100. It was also found that female crabs had higher degree of stomach fullness than the males. Overall, low Vacuity Index was recorded and there were no significant differences between male and female. Correspondence analysis between L. politum size classes and degree of stomach fullness suggests that smaller crabs tend to eat more than larger crabs. Findings of this rapid survey had highlighted some baseline information on L. politum feeding ecology in SWS that exclude the temporal effect. Thus, the long-term impact of the highway project and other development that will occur in future towards the crab population inside the sanctuary still remain uncertain.