Conservative versus Mean Risk Assessments: Implications for Superfund Policies

This paper explores how a shift to more central estimates of risk would affect EPA decisions to remediate hazardous waste sites in the Superfund program. Analysis of 141 sites indicates that the EPA's use of conservative parameter values results in risk estimates that are 27 times greater than those based on mean values. Over 40% of sites requiring remediation would shift into the discretionary cleanup range if mean parameters were used. Though this paper examines the effect of using mean parameters for contaminant concentrations, exposure duration, and ingestion rates, additional adjustments for other conservative parameters might increase this effect.     

Should heterogeneity be the basis for conservation? Grassland bird response to fire and grazing.

In tallgrass prairie, disturbances such as grazing and fire can generate patchiness across the landscape, contributing to a shifting mosaic that presumably enhances biodiversity. Grassland birds evolved within the context of this shifting mosaic, with some species restricted to one or two patch types created under spatially and temporally distinct disturbance regimes. Thus, management-driven reductions in heterogeneity may be partly responsible for declines in numbers of grassland birds. We experimentally altered spatial heterogeneity of vegetation structure within a tallgrass prairie by varying the spatial and temporal extent of fire and by allowing grazing animals to move freely among burned and unburned patches (patch treatment). We contrasted this disturbance regime with traditional agricultural management of the region that promotes homogeneity (traditional treatment). We monitored grassland bird abundance during the breeding seasons of 2001-2003 to determine the influence of altered spatial heterogeneity on the grassland bird community. Focal disturbances of patch burning and grazing that shifted through the landscape over several years resulted in a more heterogeneous pattern of vegetation than uniform application of fire and grazing. Greater spatial heterogeneity in vegetation provided greater variability in the grassland bird community. Some bird species occurred in greatest abundance within focally disturbed patches, while others occurred in relatively undisturbed patches in our patch treatment. Henslow's Sparrow, a declining species, occurred only within the patch treatment. Upland Sandpiper and some other species were more abundant on recently disturbed patches within the same treatment. The patch burn treatment created the entire gradient of vegetation structure required to maintain a suite of grassland bird species that differ in habitat preferences. Our study demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands increases variability in vegetation structure that results in greater variability at higher trophic levels. Thus, management that creates a shifting mosaic using spatially and temporally discrete disturbances in grasslands can be a useful tool in conservation. In the case of North American tallgrass prairie, discrete fires that capitalize on preferential grazing behavior of large ungulates promote a shifting mosaic of habitat types that maintain biodiversity and agricultural productivity.     

Intertidal distribution and long-term movements of Littorina irrorata (Mollusca: Gastropoda)

The distribution of Littorina irrorata Say on a low-energy barrier beach on the northern Gulf of Mexico is described, and correlated with the presence of Spartina alterniflora and other plants in the upper intertidal zone. The movements of 66 individually tagged snails were followed in the S. alterniflora zone for an average of 226 days, during which time an average of 10.6 positions were recorded per snail. The snails travelled an average total path distance of at least 995 cm, but due to contorted paths, ended up an average resultant distance of only 399 cm away from their original positions. They moved an estimated resultant distance of approximately 20 to 25 cm per activity period. Despite a slight offshore movement during the fall and winter, the snails moved more parallel to the shoreline than perpendicular to it.     

Science, Power, and System Dynamics: the Political Economy of Conservation Biology

Abstract: Frustration with the lack of action on conservation issues by governments has sparked debate around the policy role of conservation biologists. We analyzed the political economy of conservation biology, that is, of the dynamics of the political and economic structures within which conservation biology operates, and we suggest more productive means for conservation biologists to achieve conservation goals. Within the modern state, conservation goals are marginalized because the growth needs of industrial capital have the highest priority. Environmental advocacy within this system largely addresses only proximate concerns and has limited success. Science is a product of modern society, but scientists now need to foster novel institutional arrangements in which humans can function within the limits of natural systems. This entails a larger recognition of the inherent contradictions residing within current institutions that themselves depend on unsustainably high resource flows. As one critical counterbalance to these institutions, we discuss community-based management and research as primary institutions through which sustainable use of natural resources might be achieved.     

Adaptive introgression as a resource for management and genetic conservation in a changing climate

Current rates of climate change require organisms to respond through migration, phenotypic plasticity, or genetic changes via adaptation. We focused on questions regarding species’ and populations’ ability to respond to climate change through adaptation. Specifically, the role adaptive introgression, movement of genetic material from the genome of 1 species into the genome of another through repeated interbreeding, may play in increasing species’ ability to respond to a changing climate. Such interspecific gene flow may mediate extinction risk or consequences of limited adaptive potential that result from standing genetic variation and mutation alone, enabling a quicker demographic recovery in response to changing environments. Despite the near dismissal of the potential benefits of hybridization by conservation practitioners, we examined a number of case studies across different taxa that suggest gene flow between sympatric or parapatric sister species or within species that exhibit strong ecotypic differentiation may represent an underutilized management option to conserve evolutionary potential in a changing environment. This will be particularly true where advanced‐generation hybrids exhibit adaptive traits outside the parental phenotypic range, a phenomenon known as transgressive segregation. The ideas presented in this essay are meant to provoke discussion regarding how we maintain evolutionary potential, the conservation value of natural hybrid zones, and consideration of their important role in adaptation to climate.     

An Analysis of Young Driver Crash Types and the Associated Lifetime Care Cost in Victoria,Australia

Objective: The elevated crash involvement rate of young drivers is well documented. Given the higher crash risk of young drivers and the need for innovative policy and programs, it remains important to fully understand the type of crashes young drivers are involved in, and knowledge of the lifetime care cost of crashes can support effective policy development. The aim of this article is to document the number and type of young driver crashes, as well as the associated lifetime care cost over a 9-year period (2005–2013) in Victoria, Australia.

Methods: In Victoria, Australia, the Transport Accident Commission (TAC) has legislated responsibility for road safety and the care of persons injured in road crashes, irrespective of fault. TAC claims data for the period 2005–2013 were used to document the number and type of young driver crashes. Lifetime care costs (past and future payment liabilities) were calculated by Taylor Fry actuarial consultancy. License and population data were used to define the crash involvement rate of young drivers.

Results: Over the 9-year period, 16,817 claims were lodged to the TAC by drivers 18–25 years of age following a crash. There were 646 fewer drivers aged 18–25 killed and injured in 2013, compared to 2005, representing an unadjusted change of ?28.7% (?29.8% males; ?28.4% females). The total lifetime care cost of young drivers killed and injured in Victoria for the period 2005–2013 was estimated to be AU$634 million (US$493 million). Differences between males and females, single- and multivehicle crashes, and fatalities and injuries were found to be statistically significant. Run-off-road crashes and crashes from opposing direction were overrepresented in the lifetime care costs for young driver claimants. Twenty-eight injured drivers were classified as high-severity claims. These 28 claimants require additional long-term care, which was estimated to be AU$219 million; of these 28, 24 were male (85.7%). The long-term care costs for these 28 drivers (0.16%) accounts for 34.5% of the total lifetime care cost of all 18- to 25-year-old injured drivers.

Conclusions: By using no-fault lifetime care costs that account for medical and like expenses, rehabilitation, and social reintegration costs, a more accurate understanding of the cost of young driver crashes can be determined. Application of these costs to specific crash types highlights new priorities and opportunities for developing programs to reduce young driver crashes.