Poster Presentation Australian Marine Sciences Association Annual Meeting 2023

What’s on the menu? What stingray vomit tells us about species-specific resource partitioning and foraging strategies   (#362)

Jaelen N Myers 1 , Kevin Crook 1 , Michael Bradley 1 , Adam Barnett 2 , Carlo Mattone 1 , Marcus Sheaves 1
  1. James Cook University, Douglas, QLD, Australia
  2. James Cook University, Cairns, QLD, Australia

Intertidal flats provide rich foraging opportunities for juvenile stingrays. Studying diets of rays in these ecosystems is necessary for understanding how they participate in intertidal food webs and their unique feeding ecology. Rays are believed to be generalist feeders that consume a range of benthic invertebrates, but differences in dietary composition across species can be driven by their unique habitat preferences and foraging strategies. At Lucinda Beach, North Queensland, two sympatric species, Himantura australis and Pastinachus ater, employ unique foraging behaviours to feed in different patches within a shared sandflat area (Crook et al., 2022), suggesting that these species may be targeting different benthic prey and have different functional roles. To investigate this hypothesis, I used non-lethal gastric lavage to extract stomach contents from stingrays at this site. My aim was to characterise the dietary habits of these species and compare species and size classes. Calculating frequency of occurrence (%) of each prey taxa in the stomachs showed significant dietary differences between species. Specifically, Pastinachus ater consumed more polychaetes than Himantura australis, which consumed more brachyuran crabs and prawns. Dietary variability between species aligned with known differences in foraging behaviours that have been observed at Lucinda, and together, results provide evidence of species-specific resource partitioning within the sandflat boundary. Efforts are currently underway at this location to map invertebrate distributions, which will allow for exploration on how benthic prey influences prey choice and fine-scale habitat use.

  1. Crook, K. A., Sheaves, M., & Barnett, A. (2022). Species‐specific foraging behaviors define the functional roles of sympatric stingrays. Limnology and Oceanography, 67(1), 219-230.