Saturday, March 8, 2008

Hawai'i coral capitol discovered

It may seem counterintuitive to many residents, but new studies show that the island with the most live coral cover in Hawai'i is the Big Island.

(Image of Big Island corals courtesy NOAA)

Most would think of the reef flats of 'Anini on Kaua'i, or O'ahu's Kāne'ohe Bay, or perhaps the vast reef flats of South Moloka'i—but of course there are reasons for the Big Island's pre-eminence.

Live coral covers 57 percent, or 29 square miles, of the waters surrounding the Big Island of Hawaii,” said Timothy A. Battista, an oceanographer with NOAA’s Center for Coastal Monitoring and Assessment. “That is the most live coral coverage of any of the main Hawaiian islands.”

The conclusion is based on a remarkably thorough new mapping study of the coral communities of the coasts of all the islands.

The new NOAA reef mapping study is available on the Web at

It is entitled “Shallow-water benthic habitats of the Hawaiian Islands 2007.” The report has zoomable maps of the entire coastline of each island.

NOAA's press release on its report is here:

Here's what NOAA says about its new maps:

The maps are the result of the most comprehensive assessment of the extent and types of shallow-water seafloor habitats in Hawaii to date. In all, the NOAA mapping effort covered 506 square miles of ocean habitat on Hawaii, Kahoolawe, Maui, Lanai, Molokai, Oahu, Kauai, Niihau and Kaula. The Hawaii survey was part of a larger effort by NOAA and partners to map all U.S. shallow water coral reef ecosystems and associated deeper reefs.”

Why would the Big Island's reefs have more coral than other islands? Perhaps because the waters around much of the state's youngest island are cleaner, less contaminated with sediment from runoff. But also because the waters there are generally warmer, and reef corals tend to do better in warmer water.

On most of the islands in the Hawaiian Archipelago, the reefs are largely constructed of coralline algae, a plant, rather than reef corals, which are an animal that lives in a symbiotic relationship with single-celled algae.

© 2007 Jan W. TenBruggencate