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Mulholland is Member of NASA Coastal Ocean Research Team

Margaret Mulholland, an Old Dominion University biological oceanographer, is one of the primary investigators on a new NASA-funded project designed to produce a clearer picture of how climate variability and change affects the carbon cycle, productivity and relative health of coastal oceans.

The project will provide data input to validate models that are used to estimate ocean productivity. In addition, the data gathered will be used to ground-truth satellite images of ocean color that are used to extrapolate ocean productivity from space. Although the $1.1 million study, which is scheduled to extend until 2013, will focus on the coastal waters of the mid-Atlantic Bight along the East Coast of the United States, from the Gulf of Maine to Cape Hatteras, it is expected to provide insight about coastal productivity and carbon cycling as they are influenced by climate variability worldwide.

Mulholland, who is an associate professor of ocean, earth and atmospheric sciences, is collaborating with government agency scientists including Antonio Mannino and David Lary of NASA's Goddard Space Flight Center and John O'Reilly and Kimberly Hyde of the National Oceanic and Atmospheric Administration. Mannino is the team's leader and the project title is "The Impacts of Climate Variability on Primary Productivity and Carbon Distributions in the Middle Atlantic Bight and Gulf of Maine."

Researchers will conduct an extensive field campaign comprised of seven 18-20 day cruises over three years and four seasons to make measurements of ocean productivity and collect related data. At the same time NASA and NOAA scientists will examine images taken from the MODIS and SeaWiFS satellites between 1997 and 2012. Information they glean will help them connect short-term and long-term climate variability to primary productivity and organic carbon distributions along the continental margin of the East Coast.

Primary productivity in marine environments refers to the production of microscopic algae that are at the base of most marine food webs. All life on Earth relies upon primary producers who fix carbon dioxide from the atmosphere into plant biomass that can be consumed by other organisms. Primary production can be highly variable and highly sensitive to environmental and climatic factors and forcing. Like other plants, as algae grow, they take in carbon dioxide and essential nutrients from the air and water and produce oxygen, and productivity by these organisms respond to nutrient pollution and increases in atmospheric carbon dioxide caused by humans.

Mulholland and her colleagues will use their measurements of productivity in the mid-Atlantic coastal waters to evaluate the Ocean Productivity from Absorption of Light (OPAL) Model currently used to predict coastal productivity from satellite images of ocean color. "Field measurements of particulate and dissolved organic carbon, primary productivity, and the absorption coefficients of phytoplankton and colored dissolved organic matter will allow us to extend the validation range for our coastal algorithms and reduce the uncertainties in satellite-derived estimates of OPAL primary productivity," the researchers wrote in their project proposal.

The researchers note that the waters where they will conduct their field work are at the crossroads of major ocean circulation features such as the Gulf Stream and Labrador Current and are influenced by highly variable river discharge, summer upwelling, warm core rings and intense seasonal stratification. "Our work will focus on the impacts of variable river discharge, sea-surface temperature, wind stress and large-scale climate indices on primary production and particulate and dissolved organic carbon distributions," they wrote.

Because the processes being studied are not unique to the East Coast study area, "the results from the proposed activity can be applied to understanding how inter-annual and long-term variability in climate patterns can impact the carbon cycle of continental margins throughout the globe."

Mulholland's other current research includes a $500,000 award from NOAA and $244,000 project from Florida Fish and Wildlife Research Institute in which she is studying the nutrient triggers that cause deadly red tide blooms in the Gulf of Mexico, three awards from the National Science Foundation that include a $413,000 project to understand how CO2 controls oceanic nitrogen fixation and carbon flow through diazotrophs, a $137,000 project to determine the bioavailability of organic nitrogen in effluents from wastewater treatment plants, and a $276,000 project to explore the role that decay-resistant proteinaceous material plays in the sequestration of carbon and nitrogen in seawater. She also has a $66,000 award from the Virginia Environmental Endowment to determine the causes of harmful algal blooms in the James River and Lower Chesapeake Bay.

This article was posted on: April 21, 2009

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