408 research outputs found
Marine Debris Survey Manual
Over the last several years, concern has increased about
the amount of man-made materials lost or discarded at
sea and the potential impacts to the environment. The
scope of the problem depends on the amounts and types
of debris. One problem in making a regional comparison
of debris is the lack of a standard methodology. The
objective of this manual is to discuss designs and methodologies for assessment studies of marine debris.
This manual has been written for managers, researchers,
and others who are just entering this area of study
and who seek guidance in designing marine debris surveys.
Active researchers will be able to use this manual
along with applicable references herein as a source for
design improvement. To this end, the authors have synthesized their work and reviewed survey techniques that
have been used in the past for assessing marine debris,
such as sighting surveys, beach surveys, and trawl surveys,
and have considered new methods (e.g., aerial photography).
All techniques have been put into a general survey
planning framework to assist in developing different marine
debris surveys. (PDF file contains 100 pages.
WOODLAND POND SALAMANDER ABUNDANCE IN RELATION TO FOREST MANAGEMENT AND ENVIRONMENTAL CONDITIONS IN NORTHERN WISCONSIN
Woodland ponds are important landscape features that help sustain populations of amphibians that require this aquatic habitat for successful reproduction. Species abundance patterns often reflect site-specific differences in hydrology, physical characteristics, and surrounding vegetation. Large-scale processes such as changing land cover and environmental conditions are other potential drivers influencing amphibian populations in the Upper Midwest, but little information exists on the combined effects of these factors. We used Blue-spotted (Ambystoma laterale Hallowell) and Spotted Salamander (A. maculatum Shaw) monitoring data collected at the same woodland ponds thirteen years apart to determine if changing environmental conditions and vegetation cover in surrounding landscapes influenced salamander movement phenology and abundance. Four woodland ponds in northern Wisconsin were sampled for salamanders in April 1992-1994 and 2005-2007. While Bluespotted Salamanders were more abundant than Spotted Salamanders in all ponds, there was no change in the numbers of either species over the years. However, peak numbers of Blue-spotted Salamanders occurred 11.7 days earlier (range: 9-14 days) in the 2000s compared to the 1990s; Spotted Salamanders occurred 9.5 days earlier (range: 3 - 13 days). Air and water temperatures (April 13- 24) increased, on average, 4.8 oC and 3.7 oC, respectively, between the decades regardless of pond. There were no discernible changes in canopy openness in surrounding forests between decades that would have warmed the water sooner (i.e., more light penetration). Our finding that salamander breeding phenology can vary by roughly 10 days in Wisconsin contributes to growing evidence that amphibian populations have responded to changing climate conditions by shifting life-cycle events. Managers can use this information to adjust monitoring programs and forest management activities in the surrounding landscape to avoid vulnerable amphibian movement periods. Considering direct and indirect stressors such as changing habitat and environmental conditions simultaneously to better understand trends in space and time can help improve monitoring programs for this taxa, which is at major risk of continued declines
Influence of Climate Change and Postdelisting Management on Longâterm Population Viability of the Conservationâreliant Kirtland\u27s Warbler
Rapid global climate change is resulting in novel abiotic and biotic conditions and inâ teractions. Identifying management strategies that maximize probability of longâterm persistence requires an understanding of the vulnerability of species to environmenâ tal changes. We sought to quantify the vulnerability of Kirtland\u27s Warbler (Setophaga kirtlandii), a rare Neotropical migratory songbird that breeds almost exclusively in the Lower Peninsula of Michigan and winters in the Bahamian Archipelago, to proâ jected environmental changes on the breeding and wintering grounds. We develâ oped a populationâlevel simulation model that incorporates the influence of annual environmental conditions on the breeding and wintering grounds, and parameterâ ized the model using empirical relationships. We simulated independent and addiâ tive effects of reduced breeding grounds habitat quantity and quality, and wintering grounds habitat quality, on population viability. Our results indicated the Kirtland\u27s Warbler population is stable under current environmental and management condiâ tions. Reduced breeding grounds habitat quantity resulted in reductions of the stable population size, but did not cause extinction under the scenarios we examined. In contrast, projected large reductions in wintering grounds precipitation caused the population to decline, with risk of extinction magnified when breeding habitat quanâ tity or quality also decreased. Our study indicates that probability of longâterm perâ sistence for Kirtland\u27s Warbler will depend on climate change impacts to wintering grounds habitat quality and contributes to the growing literature documenting the importance of considering the full annual cycle for understanding population dynamâ ics of migratory species
Micromechanical fatigue experiments for validation of microstructure-sensitive fatigue simulation models
Crack initiation governs high cycle fatigue life and is sensitive to microstructural details. While corresponding microstructure-sensitive models are available, their validation is difficult. We propose a validation framework where a fatigue test is mimicked in a sub-modeling simulation by embedding the measured microstructure into the specimen geometry and adopting an approximation of the experimental boundary conditions. Exemplary, a phenomenological crystal plasticity model was applied to predict deformation in ferritic steel (EN1.4003). Hotspots in commonly used fatigue indicator parameter maps are compared with damage segmented from micrographs. Along with the data, the framework is published for benchmarking future micromechanical fatigue models
Micromechanical fatigue experiments for validation of microstructure-sensitive fatigue simulation models
Crack initiation governs high cycle fatigue life and is sensitive to microstructural details. While corresponding microstructure-sensitive models are available, their validation is difficult. We propose a validation framework where a fatigue test is mimicked in a sub-modeling simulation by embedding the measured microstructure into the specimen geometry and adopting an approximation of the experimental boundary conditions. Exemplary, a phenomenological crystal plasticity model was applied to predict deformation in ferritic steel (EN1.4003). Hotspots in commonly used fatigue indicator parameter maps are compared with damage segmented from micrographs. Along with the data, the framework is published for benchmarking future micromechanical fatigue models
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