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BIOTIC FACTORS IN AMPHIBIAN POPULATION DECLINES
Carey, C., D F. Bradford, J. L. Brunner, J. P. Collins, E. W. Davidson, J. E. Longcore, A. P. Pessier, AND D. M. Schock. BIOTIC FACTORS IN AMPHIBIAN POPULATION DECLINES. 1stChapter 6, Greg Linder (ed.), Amphibian Decline: An Integrated Analysis of Multiple Stressor Effects. SETAC Press, Pensacola, FL, , 153-208, (2004).
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Amphibians evolved in, and continue to exist in, habitats that are replete with many other organisms. Some of these organisms serve as prey for amphibians and others interact with amphibians as predators, competitors, pathogens, or symbionts. Still other organisms in their environment have no observable relationship with amphibians. Over time, as amphibians have come into contact with new organisms as a result of range expansions, mutations, etc, novel relationships have become established that could be detrimental, neutral, or beneficial to amphibians. This process has occurred naturally over time, independent of human involvement. Success of amphibians during their 350-million year existence must have depended in part on their ability to deal with the occurrence of new species in their habitat. However, humans have contributed to this process by transporting novel pathogens or other organisms, such as predators or competitors, into new amphibian habitats and/or changing the environment in a manner that fosters the emergence of new pathogens, and/or by manipulating the environment in ways that increase the susceptibility to pathogens.