Ecology of an important coral predator: eDNA as a novel tool to investigate different life-history stages of Crown of Thorns Seastars (Acanthaster cf. solaris)

Ecology of an important coral predator: eDNA as a novel tool to investigate different life-history stages of Crown of Thorns Seastars (Acanthaster cf. solaris)

Advisor/s

Sven Uthicke, Morgan Pratchett

College or Research Centre

AIMS@JCU

Summary of Project

Crown of Thorns Seastars (CoTS) are important coral predators. On the Great Barrier Reef, CoTS outbreaks may have been responsible for over 40% of the recent coral cover decline. The reasons for these outbreaks are still under debate, possible explanations range from bottom-up (‘nutrient limitation hypothesis’) to top-down hypothesis (‘predator removal hypothesis’). At least to some degree, the confusion about the causes is due to a lack of knowledge on the ecology of CoTS, especially of early life history stages: Planktonic larval stages are hard to distinguish from other echinoderm species and post settlement juveniles are cryptic. Our team has recently developed molecular probes which allow detection and quantification of larval stages, and potentially also juveniles. These ‘eDNA’ tools open new alleys to investigate the ecology of larvae and juveniles of CoTS, such as temporal and (large and fine scale) spatial distribution. This project falls within the Research Goals of the ‘Tropical marine water quality and impacts’ with the objective (1.3) to ‘Develop strategic research and effective solutions for the management and control of Crown of Thorns Starfish’. It is also relevant to more projects at AIMS mainly the ‘Technology development to support studies of environmental levers for COTS, and Implementation of the crown of thorns research strategy: regional strategies’. The project is well housed in a research program on Crown of thorns sea star outbreaks at AIMS. Over the last years we had several internal and external (NESP, Australian Museum, GBRMPA) research projects to develop eDNA techniques to detect CoTS. A method to quantify larvae from the plankton has now been finalised and published. Current projects (NESP2, 3) use similar techniques to develop genetic methods to identify the presence of post-settlement CoTS based on ‘free’ DNA in the water, or identify predators on CoTS by faeces analysis. Thus, this project is well placed in ongoing AIMS projects and can contribute to further applying genetic markers to resolve ecologic questions concerning detection of outbreaks and understanding causes causing outbreaks We have an ongoing collaboration on CoTS issues with Morgan Pratchett. There is a collaboration through CoTS NESP projects, and currently one of MP’s technicians is analysing settlement traps with genetic methods at AIMS PC2 lab. SU has co-edited a special issue of ‘Diversity’ with MP early this year.

Key Words

reef-degradation; crown-of thorns-seastar; molecular tools; eDNA; echinoderms

Would suit an applicant who

is highly motivated with both genetic laboratory and ecological skills who is interested in using these tools along with the development of further methods to shed more light on the ecology of CoTS and contribute to new management solutions.

Updated: 08 Apr 2020