Coral Reef Project: Oʻahu

Science Center Objects

As part of the Coral Reef Project, the USGS is working closely with other local groups to investigate poor water quality issues in Maunalua Bay on the southeast coast of Oʻahu.

Aerial view of an island with mountains, ship ports, airports, cities, and an extinct volcano.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image data of Oʻahu acquired January 13, 2010

Overview

Oʻahu encompasses 1,546 sq km (597 sq mi) and is the third largest in the Hawaiian Islands chain. Also known as The Gathering Place, Oʻahu draws more visitors than any of the other Hawaiian Islands. The island was formed from joining of the Waiʻanae and Koʻolau volcanoes. Coral reefs surround the island, although active live coral growth is limited to the leeward sides of the island or in sheltered areas on the windward coasts. Reef structures on the north shore help form the waves that draw surfers worldwide. 

Motivation

The USGS is working closely with Mālama Maunalua and the Kewalo Marine Laboratory, as part of the Hawaiʻi Local Action Strategy Plan, to investigate poor water quality issues in Maunalua Bay on the southeast coast of Oʻahu. This coral-lined embayment has seen a dramatic decline in ecosystem health, including sedimentation, invasive algae species, and a reduction in reef fish. A major factor in the decline of ecosystem health is human-induced changes on land, mainly from engineering of natural drainage gulches that have become concrete-lined channels. These channels speed up the flow of storm runoff from the uplands, increasing the discharge of freshwater, sediment and other land-based pollutants to the bay. The USGS has been instrumental in measuring water-column properties in Maunalua Bay, including waves, currents, water levels, temperature, salinity, and turbidity, to provide insight into the transport and fate of these contaminants. 

We have also assisted the National Park Service (NPS) with documentation of underwater conditions around the USS Arizona Memorial (see World War II Valor in the Pacific National Monument) in Pearl Harbor. Of special concern is the fact that the hull of the USS Arizona is deteriorating and has the potential of releasing more than half a million gallons of fuel oil into the environment. By using the same instrumentation packages that we use to monitor oceanographic conditions on coral reefs, such as currents, waves, temperature and salinity, we can help the NPS get a handle on the physical dynamics surrounding the submerged hull.

Other partners working with the USGS on Oʻahu include the National Oceanic and Atmospheric Administration (NOAA)University of HawaiʻiJames Cook UniversityUniversity of California, Santa Cruz, and The Nature Conservancy.