62 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
Monitoring of a Southern Giant Petrel Macronectes giganteus population on the Frazier Islands, Wilkes Land, Antarctica
Abstract Since 1956, Southern Giant Petrels on the Frazier Islands, East Antarctica, have been counted with different census techniques, sometimes varying within seasons and among islands, which hindered analysis of the data. Protective measures for the islands from 1986 onwards have increased the need for reliable long-term census data, but reduced the ways to collect these data. Published and unpublished data were re-examined, and population trends were reconstructed based on two relatively standardised techniques: the number of active chicks (AC) and the number of apparently occupied nests (AON) around hatching. AC-values from Nelly Island from 1959 to 1998 indicate substantial periodic fluctuations, but no consistent long-term change. Since the late 1970s, AC-values on the other two islands and AON-values suggest that the breeding population may have grown by 35%. This recent growth, however, is within the extent of periodic fluctuations observed in Southern Giant Petrel population that is stable over the long term
Top predators in relation to bathymetry, ice and krill during austral winter in Marguerite Bay, Antarctica
Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 485-499, doi:10.1016/j.dsr2.2007.11.006.A key hypothesis guiding the U.S. Southern Ocean Global Ocean Ecosystems Dynamics (U.S. SO GLOBEC) program is that deep across-shelf troughs facilitate the transport of warm and nutrient-rich waters onto the continental shelf of the Western Antarctic Peninsula, resulting in enhanced winter production and prey availability to top predators. We tested aspects of this hypothesis during austral winter by assessing the distribution of the resident pack-ice top predators in relation to these deep across-shelf troughs and by investigating associations between top predators and their prey. Surveys were conducted July-August 2001 and August-September 2002 in Marguerite Bay, Antarctica, with a focus on the main across-shelf trough in the bay, Marguerite Trough. The common pack-ice seabird species were snow petrel (Pagodroma nivea, 1.2 individuals km-2), Antarctic petrel (Thalassoica antarctica, 0.3 individuals km-2), and Adélie penguin (Pygoscelis adeliae, 0.5 individuals km-2). The most common pack-ice pinniped was crabeater seal (Lobodon carcinophagus). During both winters, snow and Antarctic petrels were associated with low sea ice concentrations independent of Marguerite Trough, while Adélie penguins occurred in association with this trough. Krill concentrations, both shallow and deep, were also associated with Adélie penguin and snow petrel distributions. During both winters, crabeater seal occurrence was associated with deep krill concentrations and with regions of lower chlorophyll concentration. The area of lower chlorophyll concentrations occurred in an area with complex bathymetry close to land and heavy ice concentrations. Complex or unusual bathymetry via its influence on
physical and biological processes appears to be one of the keys to understanding how top predators survive during the winter in this Antarctic region.This material is based upon work supported by the National Science Foundation under Grants No. OPP-9910096 (to C. Ribic), OPP-9910307 (to P. Wiebe), OPP-9632763,
OPP-0120525, OPP-0217282 and OPP-0224727 (to W. Fraser), and a Fulbright Scholarship and Office of Naval Research Grant N00014-03-0212 (to G. Lawson)
Particle export from the upper ocean over the continental shelf of the west Antarctic Peninsula: A long-term record, 1992â2007
Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 2118-2131, doi:10.1016/j.dsr2.2008.04.028.Includes supplemental materialsWe report on results of a long-term (1993-2007) time series sediment trap moored at 170 m to
the west of the Antarctic Peninsula in the mid-continental shelf region (350 m depth; 64Âș30â S,
66Âș00â W). This is a region characterized by late spring-summer diatom blooms, moderately high
seasonal primary productivity (50-150 mmol C m-2 d-1 in December-February) and high
phytoplankton and krill biomass in the seasonal sea ice zone. The mass flux ranged from near 0
to over 1 g m-2 d-1 and was near 0 to >30% organic carbon (mean 8%). Sedimentation from the
upper ocean as estimated by the trap collections at 170 m exhibited strong seasonality with high
fluxes (1-10 mmol C m-2 d-1) in November-March following ice retreat and very low fluxes
(<0.001 mmol C m-2 d-1) during the Austral winter and under sea ice cover. An average of 85%
of the annual export of 212 mmol C m-2 occurred during the seasonal peak flux episodes. Over
the trap record, the annual peak flux episode has tended to occur later in the Austral summer,
advancing by about 40 days since 1993. The time-integrated sedimentation during the peak flux
episode was <1 â 50% of the SeaWiFS-estimated primary production (mean 4%) at the trap site
over the period 1998-2006. The elemental composition of material captured in the traps had an
average C:N:P of 212:28:1, greater than the canonical Redfield values. High C:P ratios (400-
600) corresponded with the annual flux peak, indicating preferential loss of P from the sinking
particles in the summer, ice-free period. The composition of the exported material more closely
approximated the Redfield composition during the low-flux, winter period.This research was supported by NSF Grants OPP 9011927, 9632763 and 0217282 for the
Palmer Long Term Ecological Research project
The impact of buffer strips and stream-side grazing on small mammals in southwestern Wisconsin
The practice of continuously grazing cattle along streams has caused extensive degradation of riparian habitats. Buffer strips and managed intensive rotational grazing (MIRG) have been proposed to protect and restore stream ecosystems in Wisconsin. However, the ecological implications of a switch from traditional livestock management to MIRG or buffer strip establishment have not been investigated. Differences in small mammal communities associated with riparian areas on continuously grazed and MIRG pastures, as well as vegetative buffer strips adjacent to row crops, were investigated in southwestern Wisconsin during MayâSeptember 1997 and 1998. More species (mean of 6â7) were found on the buffer sites than on the pasture sites (mean of 2â5). Total small mammal abundance on buffer sites was greater than on the pastures as well; there were 3â5 times as many animals on the buffer sites compared to the pasture sites, depending on year. There were no differences in species richness or total abundance between MIRG and continuously grazed pastures in either year. Total small mammal abundance was greater near the stream than away from the stream, regardless of farm management practice but there were no differences in species richness. Buffer strips appear to support a particularly rich and abundant small mammal community. Although results did not detect a difference in small mammal use between pasture types, farm-wide implications of a conversion from continuous to MIRG styles of grazing may benefit small mammals indirectly by causing an increase in the prevalence of pasture in the agricultural landscape
POST-BREEDING SEASON HABITAT USE AND MOVEMENTS OF EASTERN MEADOWLARKS IN SOUTHWESTERN WISCONSIN
Volume: 119Start Page: 198End Page: 20
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