Algal Bloom Affecting Guam's Manell-Geus Habitat Focus Area

NOAA scientists are working with the local government and community members to determine what's causing an unidentified species of macroalgae to bloom on Guam's coasts, including the Manell-Geus Watershed Habitat Focus Area.

Last year, residents noticed thick, green mats of algae washing up on the southeastern shores of the island. Large accumulations of decaying algae now cover much of the eastern shoreline of Cocos Island, an important tourist destination.

Macroalgal blooms can create serious and long-lasting impacts to coral reef ecosystems and the people who depend on them. Manell-Geus and the surrounding region contain extensive sea grass beds, coral reefs and other habitat types that support a wealth of marine life including fish and sea turtles. Residents are concerned as the dense algal mats impede fishing, tangle in boat propellers, and shade out corals, seagrasses, and other benthic species.

Although tentatively identified as a Chaetomorpha species by local experts, genetic analysis is necessary to determine if it is a native or an invasive species. NOAA biologists will continue efforts with local partners to monitor and address this novel threat to Guam's reefs before it spreads further.

Partners in this work include: NOAA Coral Reef Conservation Program, NOAA Pacific Islands Regional Office, University of Guam Marine Laboratory, Guam Bureau of Statistics and Plans, Guam Department of Agriculture, and Guam Environmental Protection Agency.