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71.
The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U.S. Endangered Species Act. 相似文献
72.
Christine Wallgren 《Local Environment》2013,18(2):233-251
Abstract This study compares energy use for food transport to a farmers' market in Sweden with energy use for transport in the conventional food system. The farmers' market was investigated through data sampling from on-site investigations. The conventional food system was studied with the aid of life cycle assessments reported in the literature. Overall, the study found no significant differences in levels of energy use for transport to the farmers' market compared with the conventional food system. For certain products, such as fresh fruits and vegetables, transport-related energy use was much lower in the local system although the season in Sweden for this kind of product is restricted to two or three months at the end of the summer. However, there is considerable potential to increase energy efficiency in local food systems by organizing the selling in new ways and by using more energy efficient vehicles. 相似文献
73.
Oram JJ McKee LJ Werme CE Connor MS Oros DR Grace R Rodigari F 《Environment international》2008,34(8):1137-1147
A mass budget of polybrominated diphenyl ethers (PBDEs) in San Francisco Bay is developed as a first step towards understanding the local sources and transport processes controlling PBDE fate in a highly urbanized estuary. Extensive monitoring of PBDEs in estuarine water and sediment, freshwater tributaries, air, and wastewater effluents and sludges were integrated with a mass budget model to provide a synthetic view of these emerging contaminants. The Bay inventories of BDE 47 and BDE 209 in 2006 were estimated to be 33+/-3 kg and 153+/-45 kg, respectively. Empirically derived estimates of annual inputs of BDE 47 and BDE 209 from all quantifiable external sources ranged from 11 to 28 kg/y and 22 to 24 kg/y, respectively. BDE 47 loads were dominated by wastewater while runoff from local tributaries represented the largest contributor to BDE 209 loads. Model results suggest the Bay PBDE inventory is highly sensitive to changes in external loads, with degradation and outflow being the major processes governing PBDE fate. The mass budget presented provides a framework for integrating future monitoring and modeling efforts. 相似文献
74.
Becky L. Williams Vanessa Lovenburg Christine L. Huffard Roy L. Caldwell 《Chemoecology》2011,21(3):131-141
Some pelagic marine larvae possess anti-predator chemical defenses. Occasionally, toxic adults imbue their young with their
own defensive cocktails. We examined paralarvae of the greater blue-ringed octopus (Hapalochlaena lunulata) for the deadly neurotoxin tetrodotoxin (TTX), and if present, whether TTX conferred protection to individual paralarvae.
Paralarvae of H. lunulata possessed 150 ± 17 ng TTX each. These paralarvae appeared distasteful to a variety of fish and stomatopod predators, yet
food items spiked with 200 ng TTX were readily consumed by predators. We conclude that TTX alone does not confer individual
protection to paralarvae of H. lunulata, and that they possess an alternative defense. In larger doses, tetrodotoxin is a deterrent to the predatory stomatopod Haptosquilla trispinosa (mean dose = 3.97 μg/g). This corresponds to 12–13 paralarvae per predator based on the TTX levels of the clutch we examined.
Thus, the basic assumption that individual paralarvae of H. lunulata are defended by TTX alone was disproved. Instead, functionality of TTX levels in paralarvae may arise through alternative
selective pathways, such as deterrence to parasites, through kin selection, or against predator species not tested here. 相似文献
75.
Claire Suchet Laurent Dormont Bertrand Schatz Martin Giurfa Valérie Simon Christine Raynaud Jérôme Chave 《Behavioral ecology and sociobiology》2011,65(5):1015-1027
Two wild subspecies of snapdragon, Antirrhinum majus, subspecies pseudomajus and striatum, differ in floral color and can be visually discriminated by insect visitors. The extent to which olfactory cues derived
from floral scents contribute to discrimination between snapdragon subspecies is however unknown. We tested whether these
two subspecies differ in floral scent and whether these olfactory differences are used by bumblebees (Bombus terrestris) to discriminate between them. We grew individuals of both subspecies, collected from a total of seven wild populations,
under controlled conditions. We quantified the volatile organic compounds (VOCs) emitted by the flowers using gas-chromatography/mass-spectrometry/flame-ionization-detection.
We studied antennal detection of VOCs by bumblebees, by means of electroantennogram study (EAG). We also performed behavioral
experiments in a Y-maze to determine the innate response of bumblebees to the main floral VOCs emitted by our snapdragon subspecies.
The floral scent of Antirrhinum majus pseudomajus contained three volatile benzenoids absent in the floral scent of Antirrhinum majus striatum. One of them, acetophenone, contributed over 69% of the absolute emissions of A. majus pseudomajus. These benzenoids elicited a significantly higher EAG response compared with other VOCs. In the Y-maze, bumblebees were significantly
less attracted by acetophenone, suggesting an aversive effect of this VOC. Our findings indicate that bumblebees are able
to discriminate between the two Antirrhinum majus subspecies. Differences in flower scent between these subspecies and olfactory bumblebee preferences are discussed in the
light of biochemical constraints on VOCs synthesis and of the role of flower scent in the evolutionary ecology of A. majus. 相似文献
76.
Christine E. Thacker Andrew R. Thompson Dawn M. Roje Emily Y. Shaw 《Marine Biology》2008,153(3):375-385
Species of the reef goby genus Gnatholepis exhibit enormous geographic ranges with little evidence of population segregation detectable based on mitochondrial DNA.
To determine if genetic differentiation is evident with more rapidly evolving markers, seven microsatellite loci were screened
from the species Gnatholepis anjerensis and G. scapulostigma and population segregation was tested among fish from across the South Pacific. Both AMOVA and pairwise F
ST analyses showed that, in concordance with previous mitochondrial results, most genetic variance occurs within individual
populations, as population differentiation is evident only over the largest distances (>3,700 km). This result is contrasted
with previous studies demonstrating that despite their relatively long larval periods, some gobiid fishes exhibit population
differentiation on small (<100 km) geographic scales. Coalescence analysis showed that current Pacific populations of these
species originated in the Pleistocene, presumably related to sea level fluctuations associated with episodes of glaciation.
However, rate analysis based on a phylogeny of Gnatholepis species indicates that the species themselves are much older, consistent with a complex history of rapid, short-term population
contractions and expansions, with corresponding rapid dispersal. 相似文献
77.
Patterns of mtDNA diversity in North Atlantic populations of the mussel Mytilus edulis 总被引:3,自引:3,他引:0
Patterns of (female) mitochondrial DNA diversity were investigated in the blue mussel Mytilus edulis. Mytilus edulis is a ubiquitous member of contemporary North Atlantic hard-substrate communities and well represented in studies of this
region. Mytilus edulis was surveyed in North America and Europe, as well as mid-Atlantic sites in Greenland, Iceland, and the Faroe Islands. Mitochondrial
DNA sequences revealed considerable population structure but no monophyly of haplotypes between any major regions. Coalescent
analyses suggest that migration across the Atlantic Ocean has prominently been from North American source populations and
that Greenland was colonized recently and exclusively from North America. In North America, there was support for two regional
groups along the North American coastline. Surprisingly, we also found evidence of recombination between some Mytilus edulis and Mytilus galloprovincialis female mtDNA sequences, particularly in northern Europe.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
An erratum to this article can be found at 相似文献
78.
Christine R. Maher 《Behavioral ecology and sociobiology》2009,63(6):857-868
Solitary species show several patterns of space use and relatedness. Individuals may associate randomly or may live near female
or male kin, often as a result of natal philopatry or dispersal patterns. Although usually described as solitary or asocial,
woodchucks (Marmota monax) are behaviorally flexible marmots that exhibit greater sociality in some populations than others. I examined relationships
between kinship, geographic distance, and home range overlap, as well as dispersal and philopatry, to determine the extent
to which kin associated spatially. I used a combination of microsatellite DNA analysis, long-term behavioral observations,
and radiotelemetry to test predictions that females, but not males, would associate with kin. Indeed, woodchucks lived closer
and shared a greater proportion of their home range with more closely related animals. Overlap of females' and males' home
ranges was positively correlated with kinship, and male–female dyads shared more area with closer kin. Most juveniles delayed
dispersal beyond their first summer. Females often remained philopatric and settled near their natal range. Although males
often dispersed as yearlings, some males also established territories within or immediately adjacent to their natal home ranges.
A combination of factors can explain these spatial patterns, including high population density associated with the study site's
location within a suburban environment, high dispersal costs, and abundant food. Thus, despite their asocial and solitary
reputation, woodchucks displayed spatial patterns seen in other, more social species of ground-dwelling sciurids. 相似文献
79.
Christine L. Jocoy 《Journal of the American Water Resources Association》2000,36(4):811-821
ABSTRACT: Research on the condition of drinking water provision in the United States documents the inequitable financial impact of environmental regulations on small water systems (those serving 3,300 or fewer people). While a variety of federal and state financial assistance programs are available for water systems, few quantitative analyses have evaluated the success of these programs in alleviating the problems of small systems. A case study of the largest aid initiative for water supply infrastructure in Pennsylvania provides the empirical framework through which to analyze government funding opportunities for water systems. This study examines the allocation practices of the Pennsylvania Infrastructure Investment Authority (PENNVEST) to water systems of varying sizes. Utilizing data from PENNVEST applications and the Pennsylvania Department of Environmental Protection, the distribution of PENNVEST award recipients and denied applicants by size characteristics are compared. The study indicates that very small water systems (those serving 500 or fewer) do not apply for or receive funds with the same frequency as their larger counterparts. Understanding the allocation of awards from PENNVEST offers insight into the ability of small communities to access capital for water supply infrastructure. 相似文献
80.
Mainstreaming risk reduction in urban planning and housing: a challenge for international aid organisations 总被引:2,自引:0,他引:2
Wamsler C 《Disasters》2006,30(2):151-177
The effects of 'natural' disasters in cities can be worse than in other environments, with poor and marginalised urban communities in the developing world being most at risk. To avoid post-disaster destruction and the forced eviction of these communities, proactive and preventive urban planning, including housing, is required. This paper examines current perceptions and practices within international aid organisations regarding the existing and potential roles of urban planning as a tool for reducing disaster risk. It reveals that urban planning confronts many of the generic challenges to mainstreaming risk reduction in development planning. However, it faces additional barriers. The main reasons for the identified lack of integration of urban planning and risk reduction are, first, the marginal position of both fields within international aid organisations, and second, an incompatibility between the respective professional disciplines. To achieve better integration, a conceptual shift from conventional to non-traditional urban planning is proposed. This paper suggests related operative measures and initiatives to achieve this change. 相似文献