Marine Habitats and Ecosystems

A significant part of the Center's research is directed at surveying, monitoring, modeling and assessing marine habitats and ecosystems and integrating information to support an ecosystem approach to management. Research is conducted in waters within the U.S. 200-mile Exclusive Economic Zone of the Pacific Islands Region and on the high seas of the central and western Pacific. Studies range from surveys of coral reef ecosystems and oceanic habitats using NOAA research vessels to complex modeling of ocean properties and investigations of ocean warming, acidification, and other aspects of climate change. During 2010, progress was noted in several areas:

Coral Reef Ecosystems Assessed in American Samoa and the Pacific Remote Islands

Grey reef sharks at Jarvis Island.
Grey reef sharks at Jarvis Island.

In early 2010, as part of its ongoing Pacific Reef Assessment and Monitoring Program (Pacific RAMP), PIFSC scientists surveyed shallow reef ecosystems of American Samoa and several components of the U.S. Pacific Remote Island Areas —Johnston Atoll, Howland Island, Baker Island, Jarvis Island, Palmyra Atoll and Kingman Reef. PIFSC researchers were joined by partners from American Samoa and several universities. Operating from the NOAA Ship Hi'ialakai, the field party surveyed waters of all American Samoa islands, permitting comparisons with data from earlier surveys. At Rose Atoll, now protected within the Rose Atoll Marine National Monument, conditions overall were similar to those observed in 2008. Surveys at Ta'u Island indicated an increase in crustose coralline red algae and a dramatic increase in the density of an invasive didemnid tunicate. Towed divers surveying Tutuila Island noted evidence of damage to coral reefs in some areas caused by the devastating September 2009 tsunami that struck American Samoa; other islands surveyed showed no evidence of tsunami impacts. At Howland and Baker Islands, scientists observed mass coral bleaching, likely caused by elevated water temperatures associated with El Niño conditions that prevailed through winter 2009–2010. Data from temperature recorders at Howland Island show that water temperature from the sea surface to about 40 m depth increased during 2009 and remained above 30°C after mid-October; the instruments were recovered in February 2010. Bleaching was widespread and severe at both Howland and Baker, particularly on eastern sides of the islands. Coral bleaching can undermine the health of coral reefs. At Howland and Baker, branching and table corals (e.g., Acropora sp.) appeared to be more affected by the bleaching than massive corals.

High densities of giant clams were observed at Kingman Reef.
High densities of giant clams were observed at Kingman Reef.

At Jarvis Island, counts of sharks were higher in 2010 than during the 2008 survey. Reefs at Jarvis were generally dominated by hard corals. However, on the western side of the island, an area noted for upwelling, an extensive population of soft corals was found, covering almost all the sea floor at the survey depth.

At Palmyra Atoll, divers saw few giant clams or other macroinvertebrates, whereas at nearby Kingman Reef, sampling sites on the southeastern backreef continued to harbor the highest concentration of giant clams of any area explored during the Center's Pacific reef surveys.

While PIFSC researchers and colleagues were collecting new data in the 2010 Pacific RAMP surveys of American Samoa and the remote island areas, information collected in several previous Pacific RAMP expeditions was published in the Atoll Research Bulletin. The peer-reviewed journal issued three papers authored by scientists from PIFSC, the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), and the U.S. Fish and Wildlife Service. In one article, collaborating ichthyologists compiled a comprehensive list of shore fishes observed at Howland and Baker Islands (in the Phoenix Islands group) and Jarvis Island, Palmyra Atoll, and Kingman Reef (in the Line Islands group). In each location, Pacific RAMP surveys during 2000–2008 identified many fish species previously unrecorded there. In another pair of articles based on the earlier Pacific RAMP surveys, benthic ecologists described the species composition and abundance of coral communities in different reef habitats at Kingman Reef and at Rose Atoll, in American Samoa. During 2010, several other articles on the Center's coral reef ecosystem research were published in the Journal of Marine Biology. Together, the new publications expanded knowledge of corals, inshore fishes, and other biota inhabiting U.S. islands and atolls across the Pacific Islands Region. The Pacific RAMP research surveys, funded by the Coral Reef Conservation Program, study invertebrate fauna, algae, and other biota as well as corals and fishes, and provide the best available information on marine biological diversity in the U.S. Pacific islands and atolls. They provide an important record for monitoring the response of these coral reef ecosystems to climate change, ocean acidification, and land-based sources of pollution.

Survey Explores Mesophotic Coral Reefs in the Au'au Channel

In early July, 2010, scientists from PIFSC and the University of Hawaii Joint Institute for Marine and Atmospheric Research boarded the NOAA Ship Oscar Elton Sette for an expedition to the Au'au Channel between the islands of Maui and Lana'i in the main Hawaiian Islands. The cruise mission was to study a series of light-dependent deep coral reefs in the Au'au Channel. The reefs there feature luxuriant expanses of stony, or scleractinian, corals as well as macroalgae, reef fishes, and other coral reef organisms. Most reefs in Hawaii are found at depths of about 100 ft or less and are most prolific at depths of around 40 ft. The reefs studied in the Au'au Channel are unique in that they are most prolific at a depth of about 280 ft and have been found to flourish even below 400 ft. Using mixed-gas scuba technology, divers surveyed the fish community to identify fish associated with the reefs and estimate their sizes and abundance. Along the same survey transects, other divers recorded high-definition video images of the sea floor; video data will be analyzed to assess the mesophotic coral community. Scientists aboard the ship used sonar to assess the communities of small fishes, squids, and other organisms that typically live offshore but may contribute nutrients to the reefs. And the field party recovered data from oceanographic instruments deployed earlier to learn about currents, water temperature and the passage of tagged fishes over the reefs. Data from the Au'au Channel expedition and subsequent studies will help NOAA understand the factors important to the sustenance and dynamics of mesophotic reef communities and their role in local and archipelago-wide ecosystems.

Climate Model Used to Explore Possible Future Changes in the North Pacific Ocean

Ecosystem scientists at PIFSC have recently made several contributions toward better understanding of potential impacts of climate change. In 2010, they joined with a colleague at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) to explore possible future changes in the North Pacific ecosystem. These researchers used a complex computer simulation model (the NOAA GFDL Earth System Model ESM2.1) that mimics the dynamics of temperature, ocean biogeochemistry and phytoplankton. Simulations were run under the so-called A2 greenhouse gas scenario which assumes little international effort to curtail emissions of anthropogenic CO2 and other greenhouse gases. Output from the model included monthly predictions of several physical, chemical and phytoplankton quantities over the period 1998–2100 at a spatial resolution ranging from 1 degree at high latitudes to 1/3 degree at the equator.

The team used model predictions of phytoplankton density to define distinct regional ecological communities, or biomes, in the North Pacific; specifically, the temperate, subtropical, and equatorial upwelling biomes. Then they examined how the spatial extent and other characteristics of these oceanic biomes changed over time.

A key model projection was that by the end of the 21st century, the subtropical biome, marked by waters with phytoplankton density less than 1.35 g C/m2, will expand northward and southeastward, increasing in area by about 30%, while the temperate and equatorial biomes shrink by similar amounts. The model predicts a warming of ocean waters during the 21st century, with the 10°C and 20°C surface isotherms shifting northward. Further, there would be a marked expansion of waters within the subtropical and upwelling equatorial biomes warmer than 30°C, creating a new thermal habitat. The suitability of this high-temperature habitat to pelagic biota in the region is unknown.

High densities of giant clams were observed at Kingman Reef.
Hawaii lies within the subtropical biome, characterized by waters with phytoplankton density less than 1.35 g C/m2. The region is predicted to expand during the 21st century, as shown by expected boundaries for 2000 (black lines) and 2100 (red lines). Waters farther north are in the temperate biome; these regions have higher phytoplankton density.

The model's biological projections indicate that primary productivity (primary production per unit area) will increase by 17% in the equatorial biome while decreasing slightly in the other two regions by the end of the century. Total primary production by phytoplankton in the equatorial and temperate biomes will likely decrease by 15% and 38%, respectively, as those areas shrink, but will increase in the expanded subtropical biome by 26%. In each biome, proportional changes would be expected in total fish catch. Projected trends in biome carrying capacity and fish catch suggest resource managers may need to address long-term trends in fishing capacity and quota levels.

The research is slated for publication in the peer-reviewed journal Bulletin of Marine Science.

Integrated Ecosystem Assessment Program Established on the Kona Coast

The Center launched a pilot Integrated Ecosystem Assessment (IEA) program for the Kona Coast region of the island of Hawaii. The purpose of the program is to compile, synthesize and analyze information on natural and socioeconomic factors in the region, specifically in relation to identified ecosystem management goals. The Kona Coast was a natural choice for the project because of its dynamic ecology and the extensive research already done in the region. It is home to a diverse group of marine species including ornamental fishes, corals, sea turtles, cetaceans, manta rays, and more. The region supports eco-tourism, aquaculture, fisheries and other ecosystem services. The goal of the IEA program is to achieve a comprehensive understanding of the Kona Coast ecosystem enabling scientific advice for ecosystem-based management. During 2010, strides were made to develop a knowledge base and to identify key management issues, ecosystem drivers, data sources, and key research projects. The ongoing process is guided by a working group composed of Center staff and a growing list of public and private partners and collaborators. The IEA pilot program established a website which will include an interactive data portal enabling users to access and view available data. The program has also begun projects in ecosystem modeling and provided support to survey local coral reefs and develop ecosystem indicators. During July 2011, the Center will conduct a 10-day research cruise in the region to support the Kona IEA project. Then in September 2011, the project will convene a 2-day Symposium on Kona's Marine Ecosystem: Past, Present and Future. Scientists, managers and other symposium participants will share their knowledge of the Kona region's marine ecosystems; describe previous, current and planned research; and provide guidance for further IEA project development and integration.

Yellow tang are a primary target of collectors in the aquarium fish trade along Hawaii's Kona Coast.
Yellow tang are a primary target of collectors in the aquarium fish trade along Hawaii's Kona Coast.