Trophic ecology of tropical riverine and coastal sharks

Determining the trophic niche of tropical euryhaline elasmobranchs is critical to understanding their functional role as potential apex predators within estuarine ecosystems. Due to a severe decline in abundance and lack of taxonomic clarity, there is a paucity of data on the dietary preferences of euryhaline elasmobranchs that encompasses both spatial and seasonal axes of variation. Euryhaline and coastal elasmobranchs occur in moderate abundance within the World Heritage Kakadu South Alligator River, Northern Territory, Australia, which is considered a ‘near pristine’ system with populations of Glyphis garricki, Glyphis glyphis and Carcharhinus leucas. Using a novel combination of techniques, Sharon is exploring both the trophic (via stable isotopes and fatty acid analysis) and spatial (via acoustic tagging) niche occupied by a range of elasmobranch species to reveal links between these predators and their prey across wet and dry seasons along a series of key habitats throughout the length of the South Alligator River.