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.

Sunday, April 26, 2009

Does Sand Kill Corals?

Depending on the scenario, sand can hurt corals … but corals have also developed ways to protect themselves from sand or sedimentation.  Sand can affect corals in a number of ways:
  • When there are a lot of waves, sand particles can become suspended in the water column and as the waves move the water back and forth, these particles can scour the reef (and corals) like a slow but steady sand blaster.
  • When there is a lot of sand in the water, the visibility (how far you can see) and the amount of sunlight reaching the bottom is decreased.  Since corals use sunlight for energy(by way of their symbiotic zooxanthellae) this can reduce the rate at which the corals grow and in extreme cases can cause bleaching or even kill the coral.
  • Even in calmer areas, where there are not as many waves, sand can sometimes land on corals. If too much sand lands on a coral it can be smothered and killed.  ... but many corals have a way to rid themselves of this “unwanted sand.”  They can secrete a mucous layer which acts as a protective shield.  When sand lands on the coral, it gets stuck in the mucous layer and then when water motion increases, the coral sheds the mucous layer – and all the sand that was stuck to it.

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