Africa's Super Reefs

April 23, 2009

In the face of warming ocean waters due to climate change, some coral reefs off East Africa are demonstrating unusual resiliency. A WCS study shows that successful fisheries management is key.

In the face of warming ocean waters due to climate change, some coral reefs off East Africa are demonstrating unusual resiliency. Throughout the world’s seas, rising surface temperatures make reefs susceptible to fatal “bleaching”—a sickness that occurs when coral species discharge the algae that live within their tissues. But new research by the Wildlife Conservation Society (WCS) shows that the “super reefs” can get by when fisheries management improves.

The team of researchers, which included Drs. Tim McClanahan and Nyawira Muthiga of WCS, found “super reefs” in the waters between northern Madagascar, northern Mozambique, Tanzania, and southern Kenya. Their existence makes them a high priority for future conservation action.

After a 1998 bleaching event off Tanzania’s coast wiped out up to 45 percent of the region’s corals, they recovered rapidly. WCS conservationists monitored these reefs, and continue to protect the corals by training park staff in protected areas. The researchers attribute the reef recovery partly to bans on commercial fishing. Such closures allows the reef fish to thrive, and the fish, in turn, keep the algae population in check. Without enough fish to feed on the algae, it would otherwise smother the corals. Those sites without any specific management measures remain degraded; one site has experienced an explosion of sea urchins—pests that feed on corals.

The scientists also found that the structure of the reefs play a major factor in their resiliency. Tanzania’s reefs are particularly complex and experience unusual variations in current and water temperatures. These factors promote the survival of a higher diversity of coral species, including those that can quickly re-colonize after bleaching.

McClanahan sees the resilience of Northern Tanzania’s reefs as a promising sign. “This gives cause for considerably more optimism that developing countries can effectively manage their reefs in the face of climate change,” he said.

WCS is actively conserving nearly 90 percent of the world’s tropical coral reef species in priority seascapes in Belize, Indonesia, Papua New Guinea, Fiji, Kenya, and Madagascar.

From Fiji to Glover’s Reef, the Western Indian Ocean Marine Science Association (WIOMSA) and the Tiffany & Co. Foundation have provided generous support for Dr. McClanahan’s research, which examines the ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world.

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