Long-term effects of sea-weeding on degraded coral reefs

Principal Investigator

Coral reefs around the world are under threat from the combined impacts of climate change and local stressors. Often, when corals die, macroalgae (seaweeds) rapidly take over available space on a reef, with corals struggling to regain dominance once seaweeds are established. My research has shown that a low-tech, simple approach of “sea-weeding” (i.e. removing seaweed by hand) is effective in rapidly rehabilitating degraded, macroalgae-dominated reefs. Over five years, my research program on two degraded reefs of Australia’s Great Barrier Reef saw a >600% increase in coral cover where macroalgae were removed three times annually, while no change was observed in control plots. These spectacular results provide an exciting potential management approach for other seaweed-dominated areas, as sea-weeding can be achieved through collective action via citizen science. However, because reef recovery dynamics operate on decadal time-scales, it is critical to understand the long-term effects of intervention via sea-weeding. In this project, I will extend the timeframe of the established sea-weeding experiment to document the trajectory of reef recovery. Specifically, the project will transition into a "maintenance" phase of weeding once per year (rather than 2-3 times per year in the first 5 years) to establish the efficacy of less frequent intervention. The results will help inform the best-practice application of sea- weeding in reef management strategies.

01 Oct 2024 - 30 Sep 2029

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