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Weekly Highlights

MEMORANDUM

From: Gabrielle Boudreaux Bodin
Subject: Weekly Highlights, USGS National Wetlands Research Center, April 04, 2013  

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Departmental/Bureau News - Current

  • Tiny Grazers Play Key Role in Marine Ecosystem Health: Jim Grace of the USGS NWRC coauthored a paper published in Ecology entitled, Temporal shifts in top-down vs. bottom-up control of epiphytic algae in a seagrass ecosystem. This work was conducted in the context of a global decline in marine seagrass beds and is part of a worldwide experimental study of the major controls of seagrass ecosystems. The paper reports on field experiments designed to better understand the mechanisms that determine the potential consequences of overfishing and nutrient pollution on near-shore marine ecosystems. Researchers found that tiny plant-eating animals feast on the nuisance algae that grow on seagrass, ultimately helping maintain the seagrass. The grazers also serve as food themselves for animals higher on the food chain. Seagrass beds provide nurseries for commercially important fish and shellfish, such as blue crabs, red drum, and some Pacific rockfish, and also help clean water and buffer coastal communities by providing shoreline protection from storms. (Jim Grace: Lafayette, La.; 337-266-8632)

  • Invasive Species and Wetland Restoration: USGS NWRC Research Ecologist Rebecca Howard authored a paper published in the journal Wetlands that addresses issues involved with the presence of Phragmites australis (common reed), an invasive plant species, in restored wetland habitats. Non-native lineages of the grass are invasive in North American wetlands. Their presence is often considered problematic because of decreased species diversity and alterations to wetland processes such as nutrient cycling. This species is particularly challenging because both native and non-native lineages occur. The authors note that non-native species can alter a system to the extent that intended management goals are not met. Scientists documented the expansion of common reed in a degraded brackish marsh that was restored by applying dredged sediments and where the invasive reed lineage was inadvertently planted. The study verified that common reed has the potential to grow relatively rapidly and persist on dredged sediments. However, long-term rapid growth of this invasive reed may be viewed as a positive attribute in areas subject to high erosion and subsidence rates, despite reductions in species diversity. According to a recent NWRC report, Louisiana lost approximately 1,900 square miles of coastal wetlands between 1932 and 2010. Therefore, the acceptability of the presence of invasive common reed is likely to vary depending on site-specific constraints and restoration goals. (Rebecca Howard; Lafayette, La.; 337-266-8639)

  • Models Show Mangrove Forests take Advantage of Warmer Temperatures: USGS NWRC scientists Michael Osland, Richard Day, and Tom Doyle, along with Five Rivers Services scientist Nicholas Enwright, recently authored an article in Global Change Biology on the effect of winter climate on salt marshes and mangrove forests. Salt marshes and mangrove forests support important fish and wildlife habitat, improve water quality, protect coastlines, and provide recreational opportunities. Both are common coastal wetland ecosystem types that occupy similar estuarine environments but have different climatic tolerances. Mangrove trees often outcompete salt marsh grasses in warmer climates. However, mangrove forests are sensitive to freezing temperatures, and along the Gulf Coast, mangrove forests are currently found only in Florida, Louisiana, and Texas (though isolated individuals have been reported in Mississippi). Salt marshes are more dominant along colder coastlines where mangroves are not able to survive freeze events. In this study, the authors developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using habitat and observed winter temperature (1970-2000) data. Their results found that relatively small changes in the intensity and frequency of winter weather events could cause relatively dramatic landscape-scale changes. Reductions in the intensity of freeze events could lead to mangrove forests replacing salt marshes in parts of the Gulf of Mexico and southeastern Atlantic coast. (Michael Osland; Lafayette, La.; 337-266-8664)

  • NRCS LASTC Meeting Held at NWRC: The USGS National Wetlands Research Center will host the Natural Resources Conservation Service Louisiana State Technical Committee quarterly meeting on April 10. The LASTC is an advisory group coordinated by the Louisiana State Conservationist to help organize and deliver Farm Bill related program benefits. General meetings of the LASTC are scheduled four times each year or announced for special program activities. NWRC Director Phil Turnipseed is a committee member. (Phil Turnipseed; Lafayette, La.; 337-266-8501)

  • Mississippi River High-Water Inspection: On April 11, USGS NWRC Director Phil Turnipseed will accompany members of the Mississippi River Commission, staff of the U.S. Army Corps of Engineers, and MRC partners on part of the annual high-water inspection trip. The river inspection will take place aboard the USACE motor vessel Mississippi. Turnipseed will join the float at Natchez, Mississippi and will accompany the group downstream to the Old River Control Structure near Lettsworth, Louisiana. A public forum is scheduled for the morning of April 12 in Port Allen, Louisiana. The purpose of the public meeting is to exchange ideas and viewpoints with the public to allow local citizens and governments a greater voice in shaping Federal policy. Since 1879, the seven-member Presidentially appointed commission has developed and matured plans for the general improvement of the Mississippi River from the Head of Passes to the Headwaters. The MRC brings critical engineering representation to the drainage basin, which impacts 41% of the United States and 2 Canadian provinces. (Gabrielle Boudreaux Bodin; Lafayette, La.; 337-266-8655)

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