Ms Aashi Parikh1, Dr Richard O'Rorke2, Assoc Prof Emma Carroll2, Dr Els Vermeulen3, Emer Prof Robert Harcourt1, Assoc Prof Anthony Chariton1
1School of Natural Sciences, Macquarie University, Macquarie Park 2109, Australia, 2School of Biological Sciences, Waipapa Taumata Rau – University of Auckland, Auckland 1142, New Zealand, 3Marine Mammal Research Institute Whale Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield 0028, South Africa
Biography:
Aashi Parikh is a PhD researcher at the Environmental DNA and Biomonitoring lab at Macquarie University with a passion for marine mammal conservation and a growing expertise with eDNA metabarcoding. Her research output so far comprises of a record of the first sighting of a sandbar shark (Carcharhinus plumbeus) in India, a methods study comparing the use of remote operated vehicles (ROVs) and snorkellers for tropical fish surveys, and a first-author publication assessing the impact of agricultural runoff on coastal and estuarine fish assemblages in the Great Barrier Reef region using eDNA sampling.
Abstract:
Baleen whales are large filter feeders that consume enormous amounts of prey whilst simultaneously sampling the surrounding marine environment. Consequently, they serve as excellent ecosystem sentinels, responding to environmental changes in a timely manner. The gut microbiome, which is highly dependent upon diet, is a useful indicator of the health of an animal and its surrounding environment. We used whale faecal samples to characterise the diet and gut microbiome of two species of baleen whales – southern right whales (Eubalaena australis, SRWs) and Bryde’s whales (Balaenoptera edeni brydei). Extracting digested prey DNA from whale faeces has been challenging, as most extraction protocols target high molecular weight genomic DNA. We performed a pilot study using five SRW faecal samples to compare a phosphate buffer DNA extraction method along with two commercial extraction kits (the QIAamp Fast DNA Stool Mini Kit and the PowerSoil kit), with variations introduced to the protocols to optimise for shorter sequences of prey DNA. We found that the choice of extraction protocol influenced the richness, diversity and composition of prey taxa detected. The PowerSoil protocol performed well overall for richness and diversity, and a modified version of this protocol was used to process >100 whale faecal samples to examine both diet and gut microbiome. The results demonstrated the variation in cetacean gut microbial compositions between two species with different diets, and among individuals of the same species from three locations subject to different levels of anthropogenic impact, with implications for the health of each population.