University of Hawaii

UH studies runoff
effect on reefs

Researchers develop new
techniques to find how activities
on land affect isle waters

By Helen Altonn

Three University of Hawaii scientists are developing techniques to better monitor the relationship between urban runoff and coral reef damage.

"The degradation of coral reefs is a widespread phenomenon often caused in part by land-based human activity," said Fred Mackenzie, professor of oceanography.

Fertilizer runoff from urban and agricultural areas, disposal or leakage of nutrient-rich sewage, sediments from construction sites, excessive use of herbicides and pesticides and heavy metals such as lead, copper and zinc, and petroleum products from automobiles and roadways and other materials flow into the ocean from the land, he said.

John Runcie, research specialist at the Hawaii Institute of Marine Biology at Coconut Island, Robert Kinzie, professor of zoology, and Mackenzie are investigating how activities on land affect Hawaii's ocean.

The UH team is developing techniques for long-term monitoring of nutrients in the water. Results of the first continuous record of coastal water quality in Hawaii are expected late this year.

"What we want to do is identify nutrient loading in the coastal waters," said Runcie.

Generally, nutrient concentrations are measured by taking water samples, Runcie said.

"If you can take a sample every five minutes for weeks and weeks, you can get a good understanding, but that is not possible."

Runcie and Kinzie, a specialist on coral algae, are working with a submersible instrument called a pulse amplitude modulated fluorometer, one of only two in Hawaii. It rapidly measures photosynthetic rates of seaweeds and other plants and animals, such as corals and sponges.

Runcie said the device can be used on the surface or underwater.

"The way I've designed these experiments requires us to be there in person to take the measurements, but you can develop it to do it more remotely."

The researchers are focusing on Kaneohe Bay and West Maui, where a high concentration of algal growth was linked in February with nitrogen-rich fresh water from land.

Kaneohe Bay is "a world-recognized case study" for effects of nutrients on the coral reef ecosystem because of sewage previously pumped into the bay, Runcie said.

Nutrient levels in the water are fairly low now, but sporadic pulses of nutrients quickly pour into the bay after a storm, he said.

"They dissipate fairly quickly but still have an effect. What we need to do is figure out, What is the effect? Is it causing degradation of water?"

Sedimentation and other factors also come into play, he said.

Runcie said he and Mackenzie are working on different but complementary techniques of assessing nutrient concentrations in coastal waters over extended periods.

Runcie and Kinzie are using the fluorometer to look at biological organisms to indicate what is happening in the marine environment, and Mackenzie is developing continuous monitoring technology.

The Hawaii Coral Reef Initiative Research Program, established in 1998 to improve management and protection of coral reef ecosystems, is sponsoring the project.

University of Hawaii

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