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Macroinvertebrate trophic structure on waterfalls in Borneo
Waterfalls have unique physical characteristics and harbour highly specialized macroinvertebrate communities, but have been the subject of very few ecological studies. There are no previous studies of trophic structure of waterfall assemblages. It was hypothesized that due to the steep gradient of waterfalls and low retention of terrestrial based resources, the abundant basal food resources would be periphyton. In addition, due to the frequent scouring flood events, it was predicted that periphyton would be a significant source of food for filter feeders. Waterfalls in the Ulu Temburong National Park (Brunei Darussalam) were used as this case study. Methods included stable isotope analysis (SIA; δ13C and δ15N of leaf litter and periphyton) and gut contents analysis (GCA) of the most the abundant macroinvertebrates. δ15N values ranging from -1.9‰ to 5.5‰, literature suggests that this indicates there were herbivores (Heptageniidae and Blephariceridae), omnivores (Simuliidae and Hydropsychidae) and predators (Buccinidae) living on the waterfalls. Apart from Buccinidae, the taxa had δ13C signatures ranging from -33‰ to -26‰, with a high dependence on periphyton, which is like other tropical stream biotopes. This study does suggest that despite scouring velocities, waterfalls support animals with a range of diets, based on grazing/scraping, filter feeding and predation.
MF16373 Accepted 14 February 2017
© CSIRO 2017