American Samoa & the Pacific Remote Islands: The Oceanography of Jarvis Island

About the Expedition

On January 21, 2010, scientists from the Coral Reef Ecosystem Division of the NOAA Pacific Islands Fisheries Science Center (CRED/PIFSC), along with visiting scientists from the Hawaii Division of Aquatic Resources, Scripps Institution of Oceanography, San Diego State University, the US Fish and Wildlife Service, and local agencies in American Samoa, departed on a three month expedition to Johnston Atoll, Howland and Baker Islands, American Samoa, Jarvis Island, Palmyra Atoll, and Kingman Reef aboard the NOAA Ship Hi'ialakai. This is the fifth biennial Pacific Reef Assessment and Monitoring Program (Pacific RAMP) expedition to American Samoa and the seventh to the Pacific Remote Island Areas. The expedition is sponsored by NOAA's Coral Reef Conservation Program (CRCP) and is divided into three segment sequentially led by Chief Scientists Benjamin Richards, Rusty Brainard and Jamison Gove.

The strategic goal of this research is to improve scientific understanding of coral reef ecosystems throughout the Pacific, and serve as the basis for improved conservation and resource management. The recent designation of the Pacific Remote Islands Marine National Monument highlights the importance of this research.

With their extremely isolated location, many of the Pacific Remote Island Areas host a vibrate marine ecosystem. Previous Pacific RAMP cruises have documented relatively high coral cover and diversity; and high densities of large-bodied reef fish including large numbers of apex predators such as Grey Reef Sharks (Carcharhinus amblyrhynchos) and Scalloped Hammerhead sharks (Sphyraena lewini). Many of these apex predators are rare near human population centers. AS in previous years, this Pacific RAMP cruise will perform a suite of standardized multi-disciplinary methods which include Rapid Ecological Assessments (REA) for fish, corals, other large invertebrates, and algae; towed-diver surveys for large-bodied fish and habitat composition; and oceanographic studies, which include the measurement of conductivity, temperature, and density of the water column (CTD casts); water sampling; and deployment of sea-surface temperature (SST), subsurface temperature recorders (STR) and acoustic doppler current profilers (ADCP). Scientists will also be deploying Ecological Acoustic Recorders (EARs) to learn about changes in the presence and activity of marine mammals, fish, crustaceans and other sound-producing marine life when researchers aren't there to record it otherwise. Autonomous reef monitoring structures (ARMS) will also be deployed as part of the CReefs project. ARMS are simple, standardized collecting structures designed to roughly mimic the structural complexity of reef habitats. They allow for the identification of small, hard-to-sample, but ecologically important cryptic invertebrates. ARMS are being utilized throughout the Pacific and globally to systematically assess spatial patterns and temporal changes of biodiversity. Use of the EARS and ARMS are an exciting addition to RAMP data collection efforts.

Follow along below to learn more about where we are going, what we are seeing, and what we have found ...

Saturday, April 3, 2010

The Oceanography of Jarvis Island

By Jamison Gove

Grey Reef Sharks often congregate in the tens to hundreds at Jarvis Island

There is an intimate and inseparable link that exists between oceanography and coral reef ecosystems. Ocean waves, currents, temperature, salinity, and nutrient availability are each important and play a significant role in determining not only the diversity and abundance of organisms an a coral reef, but can also dictate the morphology (shape) of coral and algae species and the substrate they inhabit. For example, corals which are consistently battered by ocean waves tend to be low-lying and mound-shaped, lacking the large, delicate and branching structures that are often found in more benign, wave-free environments.

A few Raccoon Butterfly fish
make their way down the reef

In some places around the world, this connection between coral reef ecosystem dynamics and the surrounding environment can be subtle; however, at Jarvis Island this elemental relationship is so abundantly clear you would have to be sound asleep to miss it. In other words, you can actually see oceanography in action.

Schools of small fish are common
at Jarvis Island

Due to its location in the central equatorial Pacific, Jarvis is impacted by a strong, cold, nutrient-rich ocean current flowing below the surface, centered at approximately 150 meters depth. This current, known as the Equatorial Undercurrent, is spawned in the far western Pacific and flows eastward along the equator and across the entire Pacific Ocean. When this fast-moving current interacts with Jarvis Island, it forces deep water to the near-surface, providing copious amounts of nutrients to the surrounding coral, algal, and fish communities. These nutrients are quickly assimilated by the reef community, fueling an astonishingly productive and ecologically vibrant coral reef system. Few places on the planet have the oceanographic and coral reef environment that is found at Jarvis, making it a unique and special place not only for scientific research, but also for protection for many generations to come.

1 comment:

RielleApril 9, 2010 at 12:18 PM
You mention that "few places on the planet have the oceanographic and coral reef environment that is found at Jarvis"-- could you tell me what other places in the Pacific have both the oceanographic features and the high-productivity coral reef that Jarvis does? I guess what I'm wondering is how Jarvis compares to other sites where the same naturally occurring "experiment" takes place. I guess something similar happens around the Galapagos and that is a result of the Cromwell Current, as well, but how does the situation there compare to the oceanographic conditions at Jarvis? (Which is kind of a giant question, sorry-- a general answer would be awesome, or maybe just take that one as a hypothetical.) But specific to Jarvis, I wonder: does the size of the island result in differences between one side and the other; does the upwelling affect all sides equally? Also, could you briefly describe what kind of seasonal variation you see, or variation in El Nino years, and whether you've yet observed organism behavioral adaptations in relation to any variation? Thanks to everyone for all the great posts, and for answering my questions, if you have time. No rush at all, promise.
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