A tropical Pacific coral reef at Palmyra Atoll National Wildlife Refuge in the Pacific abounds with fish. Ocean warming and acidification, tied to climate change, are taking a toll on coral reefs. Photo: Jim Maragos, USFWS. Download. Photos: Coral reef photos by USFWS on Flickr

Tropical coral reefs are among the world’s most diverse ecosystems, harboring thousands of species in a complex community built by living corals. But in the Hawaiian and Pacific Islands, as elsewhere, these ecosystems are declining because of human impacts, including climate change.

“Coral reefs are on the front line of climate change,” explains Jeff Burgett, a U.S. Fish and Wildlife Service biologist and science manager for the Pacific Islands Climate Change Cooperative (PICCC), a conservation research coalition based in Honolulu and part of a national network of 21 such cooperatives. “Scientists around the world are documenting severe impacts to reefs from warming seas, and the lowering pH of the oceans will hurt their ability to recover.”   

In the Pacific, where the Service manages more than one million acres of coral reef habitat in 11 refuges, including the Hawaiian Islands National Wildlife Refuge, Service scientists are seeking ways to reduce coral vulnerability. 

High water temperatures stress corals, causing them to expel the algae they normally shelter and nourish. These algae do more than give coral their vivid colors; they also release glucose needed for healthy coral function. Without the symbiotic algae, the white skeleton of the translucent coral animal is exposed. Intense coral bleaching often leads to coral death, as the coral starves without the algae; even corals that regain their algae are weakened, and often succumb to opportunistic diseases. 

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