Dr Sven Uthicke1, Dr Maria Gomez Cabrera1, Mrs Iris Yat-Yi Lai1, Mrs Frances Patel1, Dr Kennedy Wolfe2
1Australian Institute Of Marine Science, , Australia, 2Marine Biology and Ecology Consultant, Geeveston, Australia
Biography:
Sven Uthicke is a molecular ecologist working at AIMS for over 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-thorns seastar ecology and eDNA methods for monitoring and as aquatic health indicators.
Abstract:
eDNA has become a mainstream tool for species detection and monitoring, but it also offers powerful opportunities to address questions in species biology and ecology. We illustrate this potential through studies of three life-history stages – larvae, juveniles and adults– of the Crown-of-thorns seastar (CoTS, Acanthaster cf. solaris), a coral predator whose episodic outbreaks contribute substantially to coral loss on the Great Barrier Reef.
We developed species-specific eDNA assays and used digital droplet PCR to detect and quantify CoTS eDNA. To investigate the ecology of CoTS larvae, plankton samples collected by researchers and citizen scientists were analysed for CoTS eDNA to reveal the timing, peak, and duration of the spawning period. Depth-stratified sampling resolved the previously unknown vertical distribution of larvae. Combined water-quality measurements and biophysical modelling characterised the larval environment and suggested a link between ocean upwelling and larval food supply.
The preferred locations and water depths for settlement of CoTS juveniles were revealed through eDNA detection in settlement traps. Trophic interactions were examined by eDNA screening of gut contents of potential predators of juvenile CoTS, identifying a decorator crab as an important predator and a likely contributor to population control.
Adult ecology was studied through a long-term eDNA survey program across the Great Barrier Reef, enabling early outbreak detection and documentation of outbreak progression. Collectively, these studies demonstrate how eDNA has advanced the understanding of CoTS ecology across life stages, improved the knowledge of drivers of population outbreaks, and supported more effective interventions to control of CoTS populations.