By Jan TenBruggencate
Advertiser Columnist

A team of University of Hawai'i researchers working under the umbrella of the Hawai'i Coral Reef Initiative Research Program is looking for new ways to identify land threats to marine life.

"We've been looking at stream inputs," said oceanography professor Fred Mackenzie.

Streams are one of the main avenues by which land pollutants reach the sea. Some of those pollutants are obvious, such as sewage. Others might not be so clear.

Mackenzie listed fertilizer from farms and homes, sediment in muddy water from improperly managed construction sites, various pesticides, and pollutants from roads and vehicles, such as lead, copper, zinc and oil products.

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

Coral specialist Robert Kinzie and marine scientist John Runcie also are studying the impacts.

"As we live on relatively small islands in Hawai'i, almost anything on land ultimately ends up on our coral reefs," Runcie said.

He works with a device called a pulse amplitude modulated fluorometer, which is a kind of plant stress meter, he said. "It measures the ability of the chlorophyll in marine species to absorb light."

The healthier that plants, coral or even certain sponges are, the more efficiently they process light. Unhealthy plants don't do it so well.

In some marine situations, fertilizers from the land can increase the chlorophyll capacity of almost all marine plants. At first glance, this might seem to be a good thing. But sometimes weedy or pest species may grow much faster, overwhelming the others so that the balance of life on the reef is changed.

Runcie said the researchers also are studying the role of sediments on the reef. Nutrient-rich sediments can be churned up with every storm, repeatedly changing the environment for reef creatures.

"We don't know whether that's significant or not," he said.

The researchers said coastal waters in Hawai'i tend to get hit hard by storms. For long periods there may be very little pollution flowing into coastal areas, then a rainstorm may dump immense amounts of mud, oil, fertilizer, pesticides and other pollutants at once.

Some protected areas, such as Kane'ohe Bay, Hilo Bay and Pearl Harbor, which have reduced flushing action, may be more at risk from land pollution, which stays around longer.

The coral reef research program has a Web site.

Jan TenBruggencate is The Advertiser's science and environment writer and Kaua'i bureau chief. Contact him at (808) 245-3074 or jant@honoluluadvertiser.com.