A new study from Griffith University shows that marine reserves (green zones) can help coral reefs withstand the impact of extreme floods.
Researchers from Griffith’s Australian Rivers Institute, CSIRO and the National Climate Change Adaptation Research Facility studied the impact of the catastrophic floods of early 2011 – which saw much of Queensland declared a disaster zone – on the health of coral reefs in Moreton Bay.
They found that while the floods impacted reefs for 30km from the mouth of the Brisbane River, reefs in marine reserves were better able to cope than similar fished reefs.
The research has significant implications for how society responds to conservation challenges in coastal waters, as well as for the benefits we can expect from marine reserves. The findings have been published in the prestigious journal Global Change Biology.
Floods dump large quantities of nutrients and sediment into coastal waters and this can smother inshore coral reefs and fuel the rapid growth of algae.
“On healthy coral reefs, the growth of algae is kept under control by herbivorous fish (fish that eat plants), like rabbitfish, parrotfish and surgeonfish,” says lead author Dr Andrew Olds.
“The recruitment of baby corals is also important and helps maintain coral dominance. Thus herbivory and coral recruitment are key processes that help sustain reef health.
“In Moreton Bay, coral reefs that are inside marine reserves support more herbivorous fish and also experience greater herbivory and coral recruitment than similar reefs that are open to fishing.
“This means that after the 2011 floods, algae was rapidly removed from reefs in marine reserves and not controlled on similar fished reefs.”
Coastal management and conservation
Conservation initiatives such as marine reserves are implemented with the primary objective of maintaining and enhancing biodiversity. There is now also great interest in using reserves as a management tool to help improve the health of degraded ecosystems, but this potential benefit has proven difficult to assess.
“By demonstrating that marine reserves enhanced the capacity of coral reefs to withstand flood impacts, this research shows that reserves can successfully promote the health and resilience of coastal ecosystems,” says Dr Olds, who has since relocated to the University of Sunshine Coast.
Griffith’s Professor Rod Connolly and Dr Kylie Pitt also contributed to the research which shows that local marine reserves can play an important role in protecting coastal ecosystems from future severe disturbance.