New London - Although Long Island Sound is surrounded by some of the most heavily populated and oldest communities in the country, a comprehensive and detailed scientific picture of the estuary does not exist.

That began to change Friday with the announcement of the start of a multiyear project to survey the sea floor of the Sound and map bottom habitats, marine life communities and other conditions.

"This will arguably be the most comprehensive study of Long Island Sound ever," said Ivar Babb, director of the Northeast Underwater Research Technology and Education Center located at the University of Connecticut's Avery Point campus in Groton.

Babb was among speakers at an event on the pier at Fort Trumbull State Park, where two of the vessels involved in the project were docked. UConn's RV Connecticut, normally kept at Avery Point, and the Thomas Jefferson, a 208-foot National Oceanic and Atmospheric Administration (NOAA) mapping vessel, will be joined by research vessels from other academic institutions that will collect data to characterize sediments, salinity and temperature, marine life communities and habitats.

It will begin as a pilot project in an area of the Sound between Bridgeport and Milford on the Connecticut side south to the area along the north shore of Long Island around Port Jefferson, N.Y.

"What we're here today to celebrate is an investment in science that will help us to defend a natural resource that has incalculable value for us," said Macky McCleary, deputy commissioner of the state Department of Energy and Environmental Protection.

Researchers and students from UConn, the University of Rhode Island, Wesleyan University, Stony Brook University, Columbia University and the City University of New York will be working with colleagues from NOAA, the Connecticut DEEP and its New York state counterpart, Sea Grant offices in Connecticut and New York, the U.S. Geological Survey, the U.S. Environmental Protection Agency and other partners on various aspects of the project.

The project is being funded by a $6 million settlement of a 2004 dispute between the two states that share the Sound and two power companies and a cable company over electric cable crossings that did not comply with permits.

"That (dispute) highlighted the conflicts that can occur when we don't have adequate knowledge of the habitat," said Mark Tedesco, director of the EPA's Long Island Sound office. "We would never accept not knowing where the important habitats are on the uplands."

The detailed portrait of the Sound that will emerge from the study, he said, will help government officials make better decisions about proposals affecting the estuary "in less time and less cost" than is currently possible, he said.

While much information has been gathered about the Sound over the years, he said, current technology allows for much more detailed and accurate data to be gathered that will be useful in making decisions about such areas as energy infrastructure, stewardship of marine resources, climate change adaptation and management of dredge spoils.

"We now have the ability to see and understand the sea floor in a way that we would not have had without a much more intensive effort," Tedesco said. "There is nothing that has been done that will be quite comparable to this. It will be new information and new products that we will be able to offer."

During a tour of the Thomas Jefferson after the ceremony, NOAA Corps Cmdr. Lawrence Krepp described the vessel's multibeam and side-scan sonar equipment used to map the bottom contours and create maps showing depths and navigational hazards such as large rocks and shipwrecks. "We call it mowing the grass - just moving back and forth mapping the bottom," he said, showing a screen image of the vessel passing over an area, gathering data.

Ocean floors, Krepp said, are dynamic environments that change with tides, rising sea levels and other conditions, so maps must be updated periodically for navigation as well as fisheries management and ocean planning decisions.

In one room of the vessel filled with banks of computers, Douglas Wood, senior hydrographic survey technician, explained how the sonar data is corrected for tides and errant sounds to produce accurate data that can be used to make navigational maps.

"For every hour we have of data, it takes about three hours down here," he said.

j.benson@theday.com