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125 Years of Science for America - 1879 to 2004
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U.S. Geological Survey
Open-File Report 2004-1309
Version 1.0

Application of GPS Drifters to Track Hawaiian Coral Spawning

By Gerald A. Hatcher, Thomas E. Reiss and Curt D. Storlazzi

photograph of buoy-like device floating on the ocean surface
Drifter equipped with navigation system and radio transmitter tracks the movement of newly spawned coral larvae in Hawaii.

From June 30 to July 3, 2003, scientists from the U.S. Geological Survey's (USGS) Coral Reef Project conducted an experiment to investigate one possible cause of large variations in the amount of new reef production in adjacent areas around West Maui, Hawaii. The goal was to determine whether the areas of poor growth were simply not getting enough new coral larvae recruits because of local coastal-circulation characteristics. The experiment studied the larvae dispersion by the reef-building coral Montipora capitata, locally known as "rice coral," which simultaneously release bundles of eggs and sperm into the water column each summer shortly after the new moon during spring tides. The bundles rise to the surface, break apart, and then rely on chance encounters with the eggs and sperm from other bundles for fertilization. Once fertilized, most of the eggs settle to the bottom, generally within 2 to 4 days, and attach to hard substrate to begin the creation of a new coral colony.

The project objectives are to track the water containing the Montipora capitata sperm and eggs bundles as it moved during several days from its origin above a healthy reef, a system of current drifters with an integrated real-time tracking system was developed by the USGS

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For questions about the content of this report, contact Gerald Hatcher

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Maintained by: Michael Diggles
Date created: September 20, 2004
Date last modified: September 30, 2004 (mfd)