A Better Understanding of Coral Reef Ecosystems

Pelagic predators such as these barracuda, Sphyraena qenie, are part of the coral reef ecosystem in the U.S. Line Islands (NOAA Photo by Kevin Lino).
A team of scientists have embarked from Hawai'i on a three-month survey of coral reef ecosystems at Johnston Atoll, the U.S. Phoenix Islands, the islands of American Samoa, and the U.S. Line Islands in the tropical Pacific Ocean. The overarching objective is to better understand the coral reef ecosystems of these areas, many of which are seldom explored. The research expedition is part of a regular monitoring program, conducted by the Coral Reef Ecosystem Division (CRED), headquartered in Honolulu, Hawai'i. The expedition is supported by NOAA's Coral Reef Conservation Program and involves extensive cooperation among NOAA scientists and research partners, including the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), the U.S. Fish and Wildlife Service, San Diego State University, and the Papahānaumaokuākea Marine National Monument.

The research expedition will be carried out from February 27 to May 24, 2012 aboard the NOAA ship Hi'ialakai. Under the leadership of Chief Scientists Dr. Jill Zamzow, Dr. Bernardo Vargas-Angél, and Jamison Gove, a diverse team of researchers will be conducting multidisciplinary coral reef ecosystem surveys, assessing the status of fishes, corals, algae, marine invertebrates, and the oceanographic conditions in which these organisms exist. The scientific data collected during the three-month research expedition will enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems, helping to ensure their protection for generations to come.

Saturday, May 5, 2012

The Oceanographic Conditions at 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 between coral reef ecosystems and the surrounding oceanic environment. Variability in ocean waves, currents, temperature, salinity, and nutrient availability each play a critical role in determining not only the diversity, size, and abundance of organisms, but also the morphology (shape) of coral and algal species and the substrate they inhabit. For example, corals that are consistently battered by large 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.
Manta Rays, Jarvis Island
Jarvis, in particular, is influenced by unique oceanic conditions that have a profound impact on the island's coral reef ecosystem. Owing to its location in the central equatorial Pacific, Jarvis is in the direct path of 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 hits the island, deep water is forced upward to the near-surface, providing copious amounts of nutrients to the surrounding coral reef ecosystem. These nutrients are quickly assimilated by the coral, algal, and fish communities, fueling an astonishingly productive and ecologically vibrant coral reef system. Few places on earth have the oceanic conditions and biological productivity found at Jarvis, making it an ideal location for researching the interplay between coral reef ecosystems and the environment in which they exist.

Bottlenose dolphins are a common site at Jarvis Island

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