Dr Sven Uthicke1, Mr Jason Doyle1, Dr Maria Gomez-Cabrera1, Mrs Frances Patel
1Aims, Townsville, Australia
Biography:
Sven Uthicke is a molecular ecologist working at AIMS for nearly 30 years. He investigated many different aspects of coral reef ecology, including the effect of fishing on sea cucumbers, interactive effects of climate change and land runoff on marine invertebrates, and effects of ocean acidification on a variety of taxa. His current main interests are crown of thorn seastar ecology and eDNA method for monitoring.
Abstract:
Coral loss through predation by Crown-of-Thorns Seastars (CoTS) is a major contributor to the coral reef crises in the Indo-Pacific Region. Early detection of emerging outbreaks is essential for timely intervention. However, current monitoring methods only identify established CoTS outbreaks. Working on the Great Barrier Reef (GBR), we developed an environmental DNA (eDNA) method using digital droplet PCR to detect and quantify CoTS. We collected several (12-30) samples per time and location, and use both proportion of positive samples and average copy number as metric. The proportion of positive samples exhibited a significant relationship with CoTS densities measured by scooter surveys. This metric detects CoTS distinctively below outbreak levels of around 3 Individuals ha-1, whereas the average copy number is more useful for higher densities. A five-year time series using eDNA detected a developing 5th outbreak in the Lizard Island area, where several locations were sampled. Similarly, during annual surveys of 20-30 reefs from 2021 to 2023, we also detected increasing CoTS eDNA in the northern section of the GBR. We propose to use eDNA monitoring for early outbreak detection and early management intervention. Our findings underscore the importance of proactive monitoring for mitigating the impact of CoTS on coral reefs.