Algae still poses a threat to protected reefs

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Preventing people from fishing in coral reefs does not necessarily protect them from being overrun by algae, according to a recent study.

Timothy McClanahan and coauthors publish their findings in the most recent issue of the journal Aquatic Conservation: Marine and Freshwater Ecosystems.

While it stands to reason that closing a coral reef to fisheries is likely to aid in its recovery because this would increase the number of herbivores available to graze on the algae, the results of the study, conducted in Glover's Reef Atoll in Belize, showed that this is not necessarily the case.

Field surveys were carried out over a 14-year period on eight patch reefs, divided equally between a conservation zone closed to fisheries and a general-use zone with managed fisheries. The authors found that although there was a very slight increase in the number of herbivorous fish in the protected area, this increase was neither significant, nor did it protect the hard coral from being outcompeted by algae in the protected areas.

According to the authors, the results "…suggest a need to further evaluate fisheries management systems, contingencies, and interventions that will promote coral reef resilience to climate change and ecosystem sustainability."

For more information, see the paper: McClanahan, TR, NA Muthiga and RA Coleman (2011) Testing for top-down control: can post-disturbance fisheries closures reverse algal dominance? Aquatic Conservation: Marine and Freshwater Ecosystems 21, pp. 658–675.

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