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.

Friday, September 17, 2010

Kure Atoll, the Darwin Point

By Jamison Gove

We finished work at Pearl and Hermes Atoll today, and are now en route to Kure Atoll.

Kure Atoll lies at the northwest tip of the Northwestern Hawaiian Islands at 28.50° N, 178.50° W and marks the end of a long string of islands and atolls originating 2400 kilometers away at the island of Hawaii. Kure was formed roughly 35 million years ago when the sea floor beneath it was located over the same volcanic hotspot on which the Big Island is currently situated. In fact, Kure Atoll is the vestige of what was once a volcanic island, probably not too different than Lana’i, with an expansive fringing coral reef encircling the island. Through time, Kure has gradually moved to the northwest due to plate tectonics and has slowly subsided due to the weight and higher density of the volcanic island compared to the sea floor. The coral reef surrounding the island continued to grow upward staying near the sea surface, keeping pace with the island sinking. Eventually, the volcanic island was enveloped by the sea, leaving behind a large, circular lagoon surrounded by a ribbon of coral reef.

A Landsat satellite image of Kure Atoll

In addition to being located at the northern end of the Hawaiian Archipelago, Kure Atoll is the northernmost coral atoll in the world and also lies on the Darwin Point; the point marking the geographic extent in which coral reefs are able to exist. Corals require warm and clear tropical waters to photosynthesize, grow, and maintain their hard calcium-carbonate structures. In general, ocean water temperature decreases moving away (north or south) from the equator, reaching a point where temperatures are too cold for coral reefs to grow. This is the Darwin Point, named after Charles Darwin who devised a number of theories related to coral reefs in the 1800’s. Presently, the corals at Kure Atoll are growing slightly faster than the atoll is subsiding; however, as the Pacific Plate continues to move to the northwest, Kure will slowly move beyond the Darwin Point, sink below the ocean surface and no longer be the thriving coral reef ecosystem that we know today.

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