Seasonal characterization of dugong feeding and biomass utilization on selected sites in Talibong Island

Abstract

Dugong (Dugong dugon) is an herbivorous marine mammal and feeds almost exclusively on sea grass. Previous observation of the dugong feeding behavior revealed that they feed even at intertidal flats where the sea grass beds are completely exposed in the air during low tide and also at other deeper sites, where the tidal range is about 2-6m. We used a passive acoustic monitoring system to monitor their feeding behavior. Dugongs’ feeding sounds were collected at two feeding grounds at an intertidal flat and a deep site. From the result of the comparison of feeding events during daytime to nighttime, we found dugongs mainly feed during the night (Welch t-test p<0.05). We also collected sea grasses at each feeding ground and compared the species composition of sea grasses and density of sea grass between the two sites. We calculated the feeding efficiency from the density of sea grass before and after dugong’s feeding at each site and compared to them. These comparisons revealed that there was no significant difference in the amount of sea grasses fed upon by dugong between the two feeding grounds.