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Marine Resources


November 2012 Issue

EPA Creates 3D Hypoxia Model For Prediction and Management
EPA researchers are putting together a 3D computer model of hypoxia in the Gulf of Mexico to better predict where it will occur each year and perhaps suggest ways to reduce its negative effects.

The hypoxia model, which is run on an EPA super-computer, is being tested this year and will be ready by 2013 to help environmental managers make decisions about how to control the nutrient flows upstream that cause hypoxia, EPA said.

'The model and field observations are about describing the mechanisms—now we are putting it into this spatial context,' John Lehrter, EPA research ecologist, said. 'With the model results, we can go back to decision makers and show them what degree of nutrient reduction is required.'

Previous computer models of dissolved oxygen content and hypoxia have not accounted for the changing physical characteristics, such as ocean currents, winds and temperatures, that can affect the development of hypoxia.

Lehrter and his colleagues developed the 3D model with physical oceanographers at the U.S. Naval Research Laboratory in Stennis, Mississippi, who provided data about the swirling currents where the Mississippi River meets the Gulf of Mexico.

Every summer, an area of oxygen-starved water up to 20,000 square kilometers forms across the bottom of the Gulf of Mexico, adjacent to the mouth of the Mississippi River, killing bottom-dwelling marine life below and chasing some creatures farther out to sea.

This dead zone of hypoxic water is the result of an overload of nutrients—from fertilizers and storm runoff to untreated sewage and atmospheric nitrogen—being flushed down the Mississippi and into the Gulf.

The nutrients fuel an explosion of plankton in the warm surface water, which then die and are consumed by bacteria below, robbing the bottom waters of oxygen.

The biggest casualties of the dead zone are sedentary animals, such as shellfish and worms that live on the bottom. Other fish, such as croaker and menhaden, have been victims of massive fish kills as a result of hypoxia.

The Louisiana-Texas dead zone is the second largest in the world, behind the Baltic Sea dead zone.

Rising CO2 Levels Put Coastal Resources and Economies at Risk
CO2 released from decaying algal blooms and ongoing increases in atmospheric carbon emissions leads to increased levels of ocean acidification and more stress on marine resources and coastal economies, according to a study published in September in the American Chemical Society's Environmental Science and Technology.

Ocean acidification is affecting oyster shell growth and reproduction in the Pacific Northwest. Annually, the region's oyster fishery contributes $84 million to $111 million to the West Coast's economy. Ocean acidification could put more than 3,000 jobs in the region at risk.

Acidification occurs when the ocean absorbs atmospheric CO2 from the atmosphere or from the breakdown of organic matter, which causes a chemical reaction to make it more acidic. The shell and skeleton growth of species from scallops to corals is vulnerable to ocean acidification.

Researchers William G. Sunda and Wei-jun Cai show that eutrophication—the production of excess algae from increased nutrients, e.g., nitrogen and phosphorus—is a large CO2 source in coastal waters. Sunda and Cai used a new chemical model to predict acidity increase in coastal waters over a range of salinities, temperatures and atmospheric CO2 concentrations. These predictions were verified with acidity data from the northern Gulf of Mexico and the Baltic Sea, where the observed and modeled increases in acidity from eutrophication and algal decay are well within the range that can harm marine organisms.

'Acidification processes, along with increased nutrient loading of nearshore waters, are reducing the time available to coastal managers to adopt approaches to avoid or minimize harmful impacts to critical ecosystem services such as fisheries and tourism,' Sunda said.

Seawater acidity could nearly double in waters with high salinity and temperature, and could rise up to 12 times in waters with lower salinity and temperature, the researchers found.

Japanese Whaling Economy Took Big Hit Last Season
The Sea Shepherd Conservation Society cost Japanese whalers $20.5 million in losses for the 2010-2011 whaling season in the Southern Ocean Whale Sanctuary, The New York Times, citing a Japanese newspaper, reported in October.

The society said it seeks to save as many whales as possible and to bring about the economic downfall of the Japanese whaling fleet.

Last season, the whalers took only 26 percent of their kill quota, Sea Shepherd said. The season prior, they were able to take only 17 percent due to the society's interference.

The whalers continued to operate on government subsidies last season, including some $30 million from the Japanese Tsunami Relief Fund, according to Sea Shepherd.

The society has four anti-whaling vessels prepared for December as part of Operation Zero Tolerance, which aims to bring whaling kills down to zero this season. Sea Shepherd hopes this will lead to the eviction of the whalers from the Southern Ocean Whale Sanctuary.

NOAA Grants Awarded to Study Effects of Ocean Acidification
Three new research projects have been awarded NOAA grants to examine the effects of ocean acidification on fisheries and coastal economies. The research will be incorporated into advice provided to regional fishery management councils.

The Woods Hole Oceanographic Institution will receive $682,000 to understand the connection between fluctuations of CO2 levels and ocean scallop populations, harvest and economic conditions.

The State University of New York at Stony Brook will receive $533,000 to examine bay scallops and hard clams to determine acidification's effects on each species and identify the most vulnerable regions of estuaries. The University of Washington will receive $374,000 to study a large climate model with fish populations and economic models to predict ocean conditions and economic effects.


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