3 resultados para Anthropogenic stressors

em DigitalCommons@University of Nebraska - Lincoln


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The U.S. Geological Survey (USGS) is committed to providing the Nation with credible scientific information that helps to enhance and protect the overall quality of life and that facilitates effective management of water, biological, energy, and mineral resources (http://www.usgs.gov/). Information on the Nation’s water resources is critical to ensuring long-term availability of water that is safe for drinking and recreation and is suitable for industry, irrigation, and fish and wildlife. Population growth and increasing demands for water make the availability of that water, now measured in terms of quantity and quality, even more essential to the long-term sustainability of our communities and ecosystems. The USGS implemented the National Water-Quality Assessment (NAWQA) Program in 1991 to support national, regional, State, and local information needs and decisions related to water-quality management and policy (http://water.usgs.gov/nawqa). The NAWQA Program is designed to answer: What is the condition of our Nation’s streams and ground water? How are conditions changing over time? How do natural features and human activities affect the quality of streams and ground water, and where are those effects most pronounced? By combining information on water chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA Program aims to provide science-based insights for current and emerging water issues and priorities. From 1991-2001, the NAWQA Program completed interdisciplinary assessments and established a baseline understanding of water-quality conditions in 51 of the Nation’s river basins and aquifers, referred to as Study Units (http://water.usgs.gov/nawqa/studyu.html).

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Black bears (Ursus americanus) forage selectively in natural environments. To determine if bears also forage selectively for anthropogenic resources we analyzed data on vehicles broken into by bears from Yosemite National Park, California. We classified vehicles into 9 categories based on their make and model and collected data on use (2001–2007) and availability (2004–2005). From 2001 to 2007 bears broke into 908 vehicles at the following rates: minivan (26.0%), sport–utility vehicle (22.5%), small car (17.1%), sedan (13.7%), truck (11.9%), van (4.2%), sports car (1.7%), coupe (1.7%), and station wagon (1.4%). Only use of minivans (29%) during 2004–2005 was significantly higher than expected (7%). We discuss several competing hypotheses about why bears selected minivans.

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Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997-98 is coincident with high El Niño temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations.