Mapping coral reefs' health

Three agencies have teamed up to develop digital, high-resolution maps of the nation's coral reefs in the first step in understanding and protecting these threatened habitats.

A U.S. Coral Reef Task Force working group, co-chaired by the National Oceanic and Atmospheric Administration, the U.S. Geological Survey and NASA, this month released the first detailed plan to map all U.S. coral reefs by 2007 using a mix of satellite, aircraft and data collection technologies. The project will produce the first set of comprehensive digital maps that will provide the data necessary to monitor the health, status and characteristics of coral reefs.

"There is some [anecdotal] evidence to suggest that coral reefs are in serious decline and have been for decades," said Jeff Williams, director of the USGS' coastal and marine geology program. "In many cases, we don't know the extent of coral reefs or the health of coral reefs. What we need is good, sound scientific information that partners and managers can use to make decisions on how we protect and preserve coral reefs."

Coral reefs are found off the coast of Florida, Hawaii, Guam and the U.S. Virgin Islands, among other locations. The impact of overfishing, global warming and pollution are some of the factors the government wants to study.

The task force wants to develop coral reef maps that have one- to two-meter resolution, said Mark Monaco, a marine biologist and team leader of NOAA's biogeography program. Currently, the resolution on reef maps typically is 30 meters. Maps of coral reefs have not been available in any consistent manner.

Specially equipped aircraft will provide the detailed resolution. For example, an airborne laser mapping instrument will produce accurate detailed charts of reefs located in water 25 meters to 50 meters deep. Meanwhile, a hyperspectral imager, which has been used for military applications, will for the first time be used to detail specific characteristics of the reefs. For example, the imager can pick up different shades of green that distinguish sea grass from algae.

NASA is providing its Sea-Viewing Wide Field-of-View Sensor satellite to take extensive pictures of the reefs from space, which also has never been done before.

"We're trying to use a satellite that was never designed to look for coral reefs to see whether we can retrieve information about the depth of water and what might be on the bottom of shallow water environments," said Gene Carl Feldman, an oceanographer at NASA. "We want to see if we can use [the satellite] to come up with the first map of coral reefs in the world."

Potentially, NASA can equip the International Space Station with a hyperspectral sensor and other instruments for continual worldwide coverage of reefs, Feldman said.

Ultimately, the map information will go into a geographic information system database that will integrate other information already being collected, such as the location of navigation routes and industrial discharge pipes.

Some mapping efforts already are under way in the U.S. Virgin Islands and Puerto Rico.