This report discusses the negative and positive aspects of aquaculture as an alternative to harvesting wild stocks of fish. The report defines aquaculture and describes its recent growth, as well as its ecological impact. Practices to sustain aquaculture operations, such as habitat modification and the use of wild-caught seedstock are discussed. Changes to ocean food webs, the introduction of...
This report addresses the conservation of freshwater ecosystems within the United States. A comparison of the pre-settlement and current conditions of U.S. freshwater resources is provided. Requirements for maintaining freshwater ecosystem physical and biotic components, such as flow patterns, sediment/organic inputs, temperature, light, chemical/nutrient conditions, and plant/animal assemblages...
A herd of alpine ibex (Capra ibex) struggles through deep snow. A recent study examined 45 years of census data for a population of alpine ibex in Gran Paradiso National Park in northwestern Italy. Researchers found that in the absence of natural predators and human hunting, density dependence and the severity of winter weather limit the population’s size. Severe winter weather affects populatio...
African elephants (Loxodonta Africana) have an important impact on that ecosystem type, influencing its structure, function, and composition. In Kruger National Park, South Africa, park scientists, academics, and managers work synergistically within a strategic adaptive management framework to understand and manage elephant populations as an integral component of ecosystem structure, function, and...
Different land uses have created a varied landscape in the Willamette Basin of Oregon that supports a rich array of species as well as an array of economic activities. Researchers have recently developed a spatially explicit model for analyzing the consequences of alternative land-use patterns on various species and market-oriented economic returns. They found that, with careful land-use planning,...
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