By Chip Young
To be working in Honolulu one day and then be scuba diving to conduct coral reef research in one of the world’s most remote atolls by the next morning is a surreal experience. Such a swift change of pace was the situation recently for 4 researchers from the PIFSC Coral Reef Ecosystem Division (CRED). On July 11, Jamison Gove, Noah Pomeroy, Kerry Reardon, and Chip Young joined the PIFSC cruise SE-13-05 aboard the NOAA Ship Oscar Elton Sette at Midway Atoll after an evening flight. That same night, the ship, which also supported deployment of monk seal camps for the PIFSC Protected Species Division during this cruise, transited to Kure Atoll, the northernmost atoll in the Pacific Ocean island chain known as the Northwestern Hawaiian Islands. Located more than 2000 km from Honolulu, Kure Atoll is an amazing natural environment and part of the Papahānaumokuākea Marine National Monument, established in 2006 and named a World Heritage Site in 2010.
Kure Atoll was formed roughly 35 million years ago when the seafloor beneath it was located over the same volcanic hotspot upon which the island of Hawai`i currently sits. A vestige of what was once a volcanic island, Kure Atoll now exists as a collection of very small, low-lying islands that make up less than 1 km2 of land and are encircled by an expansive fringing coral reef environment that includes 167 km2 of banks with depths less than 100 m. It was on these reefs that the CRED researchers conducted scuba dives on July 12–14 to establish long-term survey sites that will enable scientists to monitor the health of Kure Atoll’s reefs into the future.
The goal of this mission at Kure Atoll was to conduct the initial surveys of a broad, nationwide monitoring strategy that was established in 2012 by NOAA’s Coral Reef Conservation Program and is known as the National Coral Reef Monitoring Plan. This plan institutes survey methods that allow for the measurement of how the coral reef ecosystems of the United States change over time and incorporates most of the methods from CRED’s Pacific Reef Assessment and Monitoring Program that have been used to monitor the coral reef ecosystems of the U.S. Pacific islands and atolls since 2001.
During this expedition, the researchers focused on issues of global climate change through investigation of water chemistry, water temperature, reef calcification rates, and biodiversity of the small organisms living within reefs (cryptobiota). At Kure Atoll, scientists collected water samples for analysis of carbonate chemistry, including dissolved inorganic carbon, total alkalinity, salinity, and chlorophyll-a; retrieved and deployed oceanographic instruments, such as subsurface temperature recorders (STRs), and biological installations, such as calcification accretion units; and completed conductivity, temperature, and depth casts. The use of each method offers insight into the effects of global climate change and ocean acidification on the coral reefs of Kure Atoll, and after a long-term data set is compiled for these reefs, NOAA scientists will be able to identify the factors that influence ecosystem change and help managers of U.S. reef environments understand the processes that affect their areas of responsibility. Similar work is planned for other islands in the Northwestern Hawaiian Islands in September.
In addition to work at Kure Atoll during this cruise, scientists also retrieved and deployed STRs and retrieved other oceanographic instruments at Pearl and Hermes Atoll and retrieved STRs from Laysan Island.