NOAA partners with Wake-U.S. Air Force, Guam, and the Commonwealth of the Northern Mariana Islands to study the condition of coral reef ecosystems in the Western Pacific

April 19, 2007

On April 19, 2007, scientists from the Coral Reef Ecosystem Division of the NOAA Pacific Islands Fisheries Science Center (CRED/PIFSC) departed on a two-month expedition in the western Pacific aboard the NOAA Ship Hi'ialakai. This purpose of this series of three biennial Reef Assessment and Monitoring Program (RAMP) cruises is to conduct ecosystem research at Wake Island, the Territory of Guam, and numerous banks and islands in the Commonwealth of the Northern Mariana Islands (CNMI). The work is sponsored by NOAA's Coral Reef Conservation Program (CRCP). The strategic goal of this research is to improve our scientific understanding of these ecosystems as the basis for improved conservation and resource management.

Figure 1: Hurricane Ioke, August 31, 2006. Image from NASA Earth Observatory.

The first RAMP leg (HI0701), led by Chief Scientist Scott Ferguson, will visit Wake Island, where the U.S. Air Force maintains a mid-Pacific airfield, and all work there is being done in cooperation with the U.S. Air Force. A previous PIFSC/CRED cruise to Wake in October 2005 provides a baseline of biological and oceanographic data for comparison to this year's survey. In August 2005, ten months after this previous cruise, typhoon Ioke, the strongest typhoon ever recorded in the central Pacific, directly hit Wake Island and caused significant damage (Figure 1). At that time it was considered a "Super Typhoon" with sustained winds of 245 km/hr (155 mi/hr).

Figure 2. Location of REA sites at Wake Atoll surveyed in 2005 by CRED, and the relative contributions at each site of coral and macro/coralline algae to benthic biota. Source: J.Kenyon, CRED-PIFSC, unpubl. data

This year's RAMP cruise to Wake provides a unique opportunity to determine the effects of such a powerful storm on the condition of the coral reef ecosystems. A suite of standard, multi-disciplinary methods are used for research throughout the Pacific. These include Rapid Ecological Assessments (REA) for fish, corals, other large invertebrates, and algae; towed diver surveys for large fish and habitat composition; measurement of conductivity, temperature, and density of the water column (CTD casts); water sampling; and deployment of sea-surface temperature (SST) and subsurface temperature recorders (STR). Previous REA stations (Figure 2) will be re-occupied to provide the most direct comparisons possible with the 2005 pre-Ioke data that showed over 50 % coral cover in most areas. In addition to the previous research methods, multibeam sonars aboard the Hi'ialakai and the 25' survey launch AHI will be used to map the seafloor around Wake Island in water depths ranging from 15 to 3000+ m. Cruise HI0701 (April 19 to May 9) is 20 days in length and only four days will be spent at Wake Island, with the rest of the time required to transit the ~ 3000 nmi between Honolulu and Guam.

Figure 3. Islands and island bands of the Mariana Archipelago

Cruises HI0702 and HI0703 (led by Chief Scientist Dr. Robert Schroeder) are the third in a series of biennial Mariana Archipelago RAMP (MARAMP) expeditions; the previous missions were conducted in 2003 and 2005. PIFSC/CRED scientists are joined or assisted by personnel from the Guam Division of Aquatic and Wildlife Resources, the Guam Fisherman's Cooperative, the University of Guam, CNMI's Division of Environmental Quality, Division of Fish and Wildlife , Coastal Resources Management, the Commonwealth Port Authority, and U.S. Fish and Wildlife Service, U.S. National Park Service. The team will conduct research in the Mariana Archipelago using the same techniques applied at Wake Island. HI0702 research will be conducted around Guam, Rota, Tinian, and Saipan Islands from May 12-22. HI0703 (May 25 to June 9) will continue northward along the chain visiting all major islands shown in Figure 3 between Saipan and Uracus. Because of time constraints, none of the major offshore banks, to the west of the main chain, will be re-surveyed this year.

Figure 4: Shallow (20-300 m) multibeam bathymetry data were collected around Saipan, Tinian, Tatsumi Reef, and Marpi Bank (north of Saipan) in 2003 aboard the R/V AHI.
Figure 5. The rare Giant Grouper [Epinephelus lanceolatus] at Agrihan. (Photo by R. Schroeder.) CRED's previous surveys found numerical and biomass densities of large fishes to be much higher in the northernmost remote islands, compared to the heavily inhabited southern islands of the Marianas Archipelago.

One noteworthy aspect of HI0702 is PIFSC/CRED's collaboration with scientists and officers from NOAA's Office of Coast Survey (OCS) to conduct nautical charting surveys at the harbors of Rota, Tinian, and Saipan. Most of the major offshore banks around Tinian and Saipan were mapped in 2003 (Figure 4), but there are critical requirements to re-survey the harbors of these three islands. Although PIFSC/CRED scientists normally conduct benthic habitat surveys, which do not need the accuracy and documentation required for nautical charting, the mapping systems aboard the R/V AHI are identical to many used for commercial nautical charting. OCS personnel spent a week in Honolulu in March 2007 doing calibration and documentation aboard the R/V AHI in order to prepare for the upcoming mission. Habitat mapping will be continued around Guam, Rota, and Aguijan, which were not completely surveyed in 2003.

HI0703 visits the northernmost Mariana islands, several of which are active volcanoes. Anatahan volcano began erupting in May 2003, only a few months before the first Mariana expedition in fall 2003, and low level seismic activity has continued since that time. During the 2003 expedition, volcanic ash covered many of the coral reefs around Anatahan. In 2005, underwater visibility was essentially zero due to a repeated low-level eruption phase prior to our visit, and no surveys were conducted. Use of NOAA ships to study in this remote area is a critical element for successful research. MARAMP cruises are rare opportunities for CNMI scientists to visit these islands and study the fish (Figure 5), algae, corals, and other invertebrates in the area. The Hi'ialakai will transit directly back to Hawaii from Saipan in early June.