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Fieldwork

Monitoring the Coral Reef Off Moloka'i, Hawai'i


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a diver works to secure the camera package
Setting up: Securing the underwater camera package to the seabed in April 2001.
In late July and early August, scientists from the USGS and several universities converged on the south shore of the island of Moloka'i in the Hawai'ian Islands. They came to continue a project aimed at identifying changes in coral reef health due both to human and natural causes, including sediment processes. This multi-agency effort is spearheaded by Mike Field (Santa Cruz) and Bob Halley (St. Petersburg), and includes researchers from Woods Hole, Menlo Park, BRD-Corpus Christi, the University of California, University of Washington, University of Hawai'i, and University of Colorado.

A large number of offshore instruments has been deployed for continual monitoring of oceanographic conditions that may affect the reef. The instruments include wave gauges, ReefProbes (instrumented tripods that measure currents, conductivity, temperature, and turbidity), tube and rotating sediment traps, and an underwater camera system--all self-logging. Approximately every 100 days, researchers retrieve the instruments to download data ashore and refurbish the instruments before re-installing them on the reef.

the camera package on land, prior to deployment
Prepped and ready: Camera package before deployment. The Canon high-resolution digital still camera, strobe light, and battery pack are in separate underwater housings mounted within an adjustable stainless-steel frame.
This past spring, a new underwater-camera system was established on the reef to monitor the flux of sediment on and over coral. The camera system, designed by Hank Chezar (Menlo Park), consists of a Canon high-resolution digital still camera, strobe light, and battery pack, all in separate underwater housings mounted within an adjustable stainless-steel frame. The camera is positioned over a small coral colony with a gridded concrete block placed next to the colony for scale. The camera collects a digital image every four hours, day and night. The objective is to record the period and frequency of sediment stress and to correlate these data with data on swell, wind and wind waves, and tides. The results will help scientists identify the principal agents of sediment re-suspension and movements on corals of the shallow forereef (~10 m deep). This first three-month deployment successfully captured more than 650 time-series images without a missed frame.


click on any of the three images below to view a larger version
Coral and clean concrete block after initial deployment (April 27, 2001). Movement of sediment during a re-suspension event (May 19, 2001). Progressive settling of sediment on both the coral and the concrete block (June 5, 2001).
The camera at work: Examples of images from the underwater digital camera. The lines on the gridded concrete block are 2 cm apart and are used for scale. (A) Coral and clean concrete block after initial deployment (April 27, 2001). (B) Movement of sediment during a re-suspension event (May 19, 2001). (C) Progressive settling of sediment on both the coral and the concrete block (June 5, 2001).

Also participating in the field studies were researchers from BRD-Corpus Christi (Scott Carr and Marion Nipper), who sampled interstitial pore water from reef sediment to analyze for environmental toxicity. Several areas of the reef are severely degraded, and pollution, along with sedimentation stress, is being studied as a possible cause.


Related Sound Waves Stories
USGS Participates in the Moloka'i Earth Day Festivities
May, 2001
USGS Coral Reef Studies Receive Honors at Conference
June, 2000
Biologic Monitoring Sites Enhance Hawai'i Coral Reef Studies
April, 2000
CMG Coral Reef Studies Featured in Moloka'i's Newspaper
March, 2000
Coral Reef Studies on Moloka'i: a Progress Report
December, 1999
USGS Looks at Moloka'i's Coral Reefs
May, 1999

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California Offshore Oil Seeps

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Coastal Issues at GSA

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