Dr Katrina West1, Sahan Jayasinghe1, Florian Devloo-Delva1, Bruce Deagle1
1CSIRO, , Australia
Biography:
Dr Katrina West is a Research Scientist at CSIRO specialising in eDNA-based technology for marine species monitoring. She completed her PhD at Curtin University (2016–2020), applying eDNA metabarcoding in novel environments such as aquatic caves and across large spatial scales in Australia's Indian Ocean region to identify biogeographic breaks in marine biodiversity. As a CSIRO Postdoctoral Fellow (2021–2024) with the Australian National Fish Collection, she conducted large-scale eDNA surveys of marine fishes and sharks across coastal and offshore ecosystems. Katrina now works within CSIRO's Environomics Team, developing new approaches for eDNA enrichment, quantification and ecological modelling.
Abstract:
The gradual warming of sea-surface temperatures, punctuated by severe marine heatwaves, is driving the ‘tropicalisation’ of temperate marine communities worldwide. Early detection of climate-driven poleward range expansions is critical given the potential displacement and local extinction of temperate taxa, with subsequent effects on ecosystem dynamics, food security and coastal economies. Environmental DNA (eDNA) metabarcoding provides a powerful whole-ecosystem approach to characterise marine communities and detect emerging biogeographic change. A suite of eDNA metabarcoding assays was applied to profile marine vertebrate and invertebrate communities across three Australian tropical-temperate transition zones: the Houtman Abrolhos Islands (WA), Solitary Islands (NSW) and Lord Howe Island (NSW). Across all regions, 2,329 marine taxa were detected, including 628 new taxa occurrence records at the Abrolhos Islands, 493 at the Solitary Islands and 456 at Lord Howe Island. Numerous previously unrecorded tropical fishes and corals were detected at higher-latitude reefs, providing a clear signal of marine tropicalisation. Furthermore, to investigate whether these changes may extend to higher trophic levels, eDNA from 100 Australian Lesser Noddy (Anous tenuirostris melanops) guano samples collected at the Abrolhos Islands was also analysed. Diet detections included both temperate and tropical fishes, including tropical taxa not previously recorded in the species’ diet. These findings demonstrate the value of eDNA for broad-scale, non-invasive detection of climate-driven biogeographic change across multiple trophic levels, while providing early-warning signals for targeted ecological validation.