University of Connecticut researchers have won a federal grant of nearly $160,000 toward a project this fall and winter to study whether cultivated seaweed can help remove harmful nitrogen and carbon, which sap oxygen from Long Island Sound.

The grant is part of $760,000 for research being distributed through the Long Island Sound Futures Fund, a partnership of the federal Environmental Protection Agency and the Long Island Sound Study.

The study -- to be directed by Charles Yarish, a professor in UConn's Department of Ecology and Evolutionary Biology and Marine Sciences -- will grow sugar kelp, a native brown seaweed, at three sites in Long Island Sound and gauge whether it helps lower harmful levels of nitrogen.

"This is a very important project," Yarish said. "Ultimately, the aim is to increase the use of `green infrastructure,' meaning natural biological materials, to reduce water pollution in the Sound and provide a new source of jobs for the region."

Higher nitrogen levels caused by sewage plant discharges and other sources, such as agriculture, gardens, and stormwater runoff, cause a condition known as hypoxia, or depletion of oxygen, which harms or kills marine life, including crabs and fish.

Elevated nitrogen levels enable growth of aquatic micro-algae, which, when consumed by oxygen-using bacteria can cause oxygen levels to plummet, Yarish said.

The three experiment sites are near the mouth of the Bronx River, off the coast of Fairfield, and in the Thimble Islands near Branford. The study will involve high school and in-state college students along with UConn researchers and commercial fishermen.

The goal is to remove 53 pounds of nitrogen and 343 pounds of carbon at the test sites, and then see how the work can be scaled up by the cultivation of the kelp.

In 2011, the amount of daily trade-equalized nitrogen discharges from Connecticut sources increased from 9,900 pounds to just over 11,000 pounds according to the state Department of Energy and Environmental Protection. The trade-equalized total aims to take into account mitigating factors, thus reflecting the true impact of nitrogen discharges.

The effects of an especially hot summer also created more extensive hypoxia in Long Island Sound during 2012 so far than in 2011, said Mark Tedesco, director of the EPA's Long Island Sound office.

On average, the condition of hypoxia has covered 288.5 square miles of Long Island Sound, compared to 130.3 square miles in 2011, according to the Long Island Sound Study Water Monitoring Program.

"Year to year there is variability influenced by weather conditions, water conditions and wind," Tedesco said. "Because of the very warm temperatures and not having much storm mixing to re-aerate the waters we had more severe hypoxia."