Streams Show Signs of Degradation at Earliest Stages of Urban Development plus 2 more

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Title: USGS Newsroom

Streams Show Signs of Degradation at Earliest Stages of Urban Development plus 2 more

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• Streams Show Signs of Degradation at Earliest Stages of Urban Development
• USGS Study Tracks Pacific Walrus, Observes Effects of Arctic Sea Ice Loss on Behavior
• Project to Support Future Global Food Security Enhanced by Major NASA Grant

Streams Show Signs of Degradation at Earliest Stages of Urban Development

Posted: 15 Nov 2012 06:12 AM PST

The loss of sensitive species in streams begins to occur at the initial stages of urban development, according to a new study by the USGS. The study found that streams are more sensitive to development than previously understood.

"We tend not to think of waterways as fragile organisms, and yet that is exactly what the results of this scientific investigation appear to be telling us," said USGS Director Marcia McNutt. "Streams are more than water, but rather communities of interdependent aquatic life, the most sensitive of which are easily disrupted by urbanization."

Contaminants, habitat destruction, and increasing streamflow flashiness resulting from urban development can degrade stream ecosystems and cause degradation downstream with adverse effects on biological communities and on economically valuable resources, such as fisheries and tourism.

For example, by the time urban development had approached 20 percent in watersheds in the New England area, the aquatic invertebrate community had undergone a change in species composition of about 25 percent.

The study also found that the health of highly-degraded streams can be improved by implementing management actions that are designed to reduce specific stressors.

"Biological communities were not resistant to even low levels of urban development. In the study sensitive invertebrate species were being lost over the initial stages of development in relatively undisturbed watersheds," said Dr. Gerard McMahon, lead scientist on the study. "Understanding how stream ecosystems are impacted by urban development can assist in the development of management actions to protect and rehabilitate urban stream ecosystems."

Multiple streams in nine metropolitan areas across the continental U.S. were sampled to assess the effects of urban development on stream ecosystems. Study areas include Atlanta, Ga., Birmingham, Ala., Boston, Mass., Dallas, Texas, Denver, Colo., Milwaukee, Wis., Portland, Ore., Raleigh, N.C., and Salt Lake City, Utah.

The study also found that the effects of urbanization on the biological community vary geographically depending on the predominant land cover and the health of the community prior to urban development. In the study, the greatest loss of sensitive species occurred in Boston, Portland, Salt Lake City, Birmingham, Atlanta, and Raleigh metropolitan areas, where the predominant land cover was forested prior to urban development. The smallest loss of sensitive species occurred in Denver, Dallas, and Milwaukee metropolitan areas where land cover was primarily agriculture before urban development.

"The reason for this difference was not because biological communities in the Denver, Dallas, and Milwaukee areas are more resilient to stressors from urban development, but because the biological communities had already lost sensitive species to stressors from pre-urban agricultural land use activities," said McMahon.

Although urban development creates multiple stressors, such as an increase in concentrations of insecticides, chlorides, and nutrients, that can degrade stream health—no single factor was universally important in explaining the effects of urban development on stream ecosystems. The USGS developed an innovative modeling tool to predict how different combinations of urban-related stressors affect stream health. This tool, initially developed for the New England area, can provide insights on how watershed management actions to improve one or more of these stressors may increase the likelihood of obtaining a desired biological condition.

The effects of urbanization on streams, including information about this and past studies, as well as graphics and maps, and videos can be online.

Results of this nationwide study and details about the effects of urbanization on the nine metropolitan areas can be found in a new USGS publication titled, "Effects of urban development on stream ecosystems in nine metropolitan study areas across the United States."

Management strategies used throughout the U.S. to reduce the impacts of urban development on stream ecosystems are described in a new USGS report written in partnership with the Center for Watershed Protection in Maryland titled, "Strategies for Managing the Effects of Urban Development on Streams.”

This study was done by the USGS National Water-Quality Assessment Program, which conducts regional and national assessments of the nation’s water quality to provide an understanding of water-quality conditions, whether conditions are getting better or worse over time, and how natural features and human activities affect those conditions.

USGS Study Tracks Pacific Walrus, Observes Effects of Arctic Sea Ice Loss on Behavior

Posted: 14 Nov 2012 02:00 PM PST

ANCHORAGE, Alaska — Sparse summer sea ice in the Arctic over the past five years has caused behavioral changes in Pacific walruses according to research published by U.S. Geological Survey and Russian scientists. The effects on the walrus population are unknown.

"The loss of sea ice is the 'why' for the change in walrus behavior; the tracking data tells us the 'where' in terms of their new forage patterns," said USGS Director Marcia McNutt. "What awaits to be seen is 'how much will it matter?'"

Using a simple darting system, scientists attached radio-tracking tags to 251 walruses in the Chukchi Sea. The tags transmitted the animals’ whereabouts and whether they were in the water and feeding. Using the tagging data gathered from 2008-2011, scientists created detailed maps of the walruses’ seasonal movements and feeding patterns relative to the location and amount of sea ice. 

The study found that due to earlier melting of the ice in the summer, walruses arrived earlier to their northern feeding grounds on the broad continental shelf of the Chukchi Sea. When the sea ice over the continental shelf melted completely in the fall, they "hauled out" onshore in large aggregations and foraged for food closer to shore. Hauling out refers to the behavior associated with seals and walruses of temporarily leaving the water for sites on land or ice. 

The specific effects of these behavioral changes are not yet understood; however, it is known that while onshore, young walruses are susceptible to mortality from trampling. Additionally, hauling out onshore and using nearshore feeding areas may require more energy. 

Adult female walrus on ice floe photographed shortly after receiving a behavior monitoring satellite-linked radio tag from USGS researchers.

Data acquired from such radio-tags are providing insights on the distribution and behavior of Pacific walruses during a time when their summer sea ice habitat is rapidly changing.

The longer open water season in the Arctic is creating opportunities for shipping, tourism, energy production and other human activities in this remote region. Data from this study will provide resource managers with basic information on areas important for walruses, such as the Hanna Shoal region, as human activities in the Arctic increase. The areas of walrus foraging overlap with oil and gas lease blocks administered by BOEM.

The information gained through tracking large marine mammals such as polar bears and walruses, is helping USGS scientists understand how disappearing Arctic sea ice is affecting the region's ecosystems. The Arctic sea ice is melting faster than forecasted by many of the top climate models: the first ice free summer is now predicted to occur by 2035, perhaps as soon as 2025. 

The U.S. Fish and Wildlife Service's Alaska Regional Director Geoffrey Haskett said, "The U.S. Fish and Wildlife Service welcomes this new research from our valued partners at USGS. It will provide us with yet another piece of information to consider as we develop management actions for this iconic arctic species."

A new film, "Tracking Pacific Walrus: Expedition to the Shrinking Chukchi Sea Ice," explores the walruses habitat and follows USGS researchers as they conduct their studies in the Arctic. The USGS-produced film contains exclusive footage of the large mammals in their natural habitat.  B-roll footage is also available online.

The study, published as this month’s feature article in the journal Marine Ecology Progress Series, is part of the USGS Changing Arctic Ecosystems initiative at the Alaska Science Center.

 

Project to Support Future Global Food Security Enhanced by Major NASA Grant

Posted: 14 Nov 2012 11:23 AM PST

A $3.5 million dollar, 5-year grant from the NASA program: Making Earth System Data Records for Use in Research Environments (MEaSUREs), was recently awarded to a U.S. Geological Survey led, multi-agency team of scientists studying future global food security. 

The proposal, "Global Cropland Area Database (GCAD30) through Landsat and MODIS Data Fusion for the Years 2010 and 1990 and Its Dynamics Over Four Decades using AVHRR and MODIS", was one of 27 awardees, and was developed as a product from a USGS-supported John Wesley Powell Center for Earth System Science Analysis and Synthesis Working Group, Global Croplands and Their Water Use for Food Security in the 21^st Century. 

"The trends in land use to feed a growing global population derived from this landmark effort will inform critical studies in planetary sustainability, such as the availability of fresh water and fertile soil, and the effects of increasingly intense cultivation on essential carbon and nitrogen cycles," said USGS Director Marcia McNutt. "It is through the unbiased eye of these satellites that we see how a myriad of independent local decisions can sum up to major global impact." 

The main goal of this project is to produce consistent and unbiased estimates of global agricultural cropland areas, types, watering method, and intensities using multi-sensor Earth Observation Data from satellites and mature cropland mapping algorithms. The project will create a Global Cropland Area Database, consisting of four distinct products. The series will include cropland extent\area, crop type, irrigated versus rainfed crops, and cropping intensity. 

"The data and products will make a significant contribution towards addressing global water and food security in the 21^st century, taking into consideration complexities of ballooning populations, greater nutritional demands from the expanding economies, and virtual water and food trade of modern, globally inter-linked economies," said Dr. Prasad Thenkabail, the project's principal investigator. 

"We are thrilled to see this kind of product from the USGS Powell Center; it is a shining example of how multidisciplinary synthesis efforts can advance the state of the science," said Jill Baron, Powell Center Co-Director. 

Team members are listed on the Current Projects site.