The Detroit River: effects of contaminants and human activities on aquatic plants and animals and their habitats

Despite extensive urbanization of its watershed, the Detroit River still supports diverse fish and wildlife populations. Conflicting uses of the river for waste disposal, water withdrawals, shipping, recreation, and fishing require innovative management. Chemicals added by man to the Detroit River have adversely affected the health and habitats of the river's plants and animals. In 1985, as part of an Upper Great Lakes Connecting Channels Study sponsored by Environment Canada and the U.S. Environmental Protection Agency, researchers exposed healthy bacteria, plankton, benthic macroinvertebrates, fish, and birds to Detroit River sediments and sediment porewater. Negative impacts included genetic mutations in bacteria; death of macroinvertebrates; accumulation of contaminants in insects, clams, fishes, and ducks; and tumor formation in fish. Field surveys showed areas of the river bottom that were otherwise suitable for habitation by a variety of plants and animals were contaminated with chlorinated hydrocarbons and heavy metals and occupied only by pollution-tolerant worms. Destruction of shoreline wetlands and disposal of sewage and toxic substances in the Detroit River have reduced habitat and conflict with basic biological processes, including the sustained production of fish and wildlife. Current regulations do not adequately control pollution loadings. However, remedial actions are being formulated by the U.S. and Canada to restore degraded benthic habitats and eliminate discharges of toxic contaminants into the Detroit River.Contribution 738 of the National Fisheries Research Center-Great Lakes, 1451 Green Road, Ann Arbor, MI 48105, U.S.A.     

EMAP-Wetlands: A sampling design with global application

The U.S. Environmental Protection Agency (EPA) initiated the Environmental Monitoring and Assessment Program (EMAP) in 1988. The wetland component (EMAP-Wetlands) is designed to provide quantitative assessments of the current status and long-term trends in the ecological condition of wetland resources. EMAP-Wetlands will develop a wetland monitoring network and will identify and evaluate indicators that describe and quantify wetland condition. The EMAP-Wetlands network will represent a probability sample of the total wetland resource. The EMAP sample is based on a triangular grid of approximately 12,600 sample points in the conterminous U.S. The triangular grid adequately samples wetland resources that are common and uniformly distributed in a region, such as the prairie pothole wetlands of the Midwest. However, the design is flexible and allows the base grid density to be increased to adequately sample wetland resources, such as the coastal wetlands of the Gulf of Mexico, which are distributed linearly along the coast. The Gulf sample network required a 49-fold increase in base grid density. EMAP-Wetlands aggregates the 56 U.S. Fish and Wildlife Service's (FWS) National Wetland Inventory (NWI) categories (Cowardin et al. 1979) into 12 functionally similar groups (Leibowitz et al. 1991). Both the EMAP sample design and aggregated wetland classes are suitable for global inventory and assessment of wetlands.The research described in this report has been funded by the U.S. Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, OR, through contract No. 68-C8-0006 to Man Tech Environmental Technology, Inc. This paper has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Short Notices

Burkardt, Nina. (1990) Opportunities to Protect Instream Flows and Wetland Uses of Water in Florida. U.S. Fish and Wildlife Service, Biological Report
Wolff S.W., Wesche T.A., Harris D.D. & Hubert W.A. (1990) Brown trout population and habitat changes associated with increased minimum low flows in Douglas Creek, Wyoming. U.S. Fish and Wildlife Service, Biological Report
Clark Donald R. Jr (1990) Dicofol (Kelthane) as an Environmental Contaminant: A Review. U.S. Fish and Wildlife Service, Fish and Wildlife Technical Report
Todd Thomas N. (1990) Genetic differentiation of walleye stocks in Lake St. Clair and western Lake Erie. United States Department of the Interior Fish and Wildlife Service. Fish and Wildlife Technical Report
Hudson Patrick L., Lenat David R., Caldwell Broughton A. & Smith David (1990) Chiro-nomidae of the Southeastern United States: a checklist of species and notes on biology, distribution and habitat. United States Department of the Interior Fish and Wildlife Service. Fish and Wildlife Research
Eisler Ronald (1990) Chlordane hazards to fish, wildlife and invertebrates: a synoptic review. United States Department of the Interior Fish and Wildlife Service. Biological Report
Eisler Ronald (1990) Paraquat hazards to fish, wildlife and invertebrates: a synoptic review. United States Department of the Interior Fish and Wildlife Service. Biological Report
Gopal Brij. (Ed.) (1990) Ecology and Management of Aquatic Vegetation in the Indian Subcontinent     

Public–private partnership wetland restoration programs benefit Species of Greatest Conservation Need and other wetland-associated wildlife

US federal conservation programs, including the National Resource Conservation Service’s Wetland Reserve Program (WRP) and the US Fish and Wildlife Service’s Partners for Fish and Wildlife Program (PFWP), partner with private landowners to conserve and restore wetland habitats. Despite the success of these programs in terms of wetland area enrolled, uncertainties exist as to whether they are meeting their stated goals, including the restoration of wildlife habitat. In the St. Lawrence Valley of New York State, we investigated two questions related to WRP and PFWP wetland restorations. First, was whether restorations provide habitat for wetland-associated wildlife, including Species of Greatest Conservation Need (SGCN) prioritized by the New York State Wildlife Action Plan (SWAP). Second, was whether restorations support wildlife assemblages that are comparable to natural reference wetlands. Bird, anuran, turtle, snake, and fish species assemblages were surveyed at 47 WRP and PFWP restorations, and 18 natural reference wetlands. We detected 31 SGCN at restorations, including SGCN from each assemblage surveyed. Assemblage metrics, including species richness and relative abundance, did not differ between restored and reference wetlands for any of the assemblages surveyed. These results indicate that restorations provide habitat for SGCN and other wetland-associated wildlife, and that assemblages at restorations are similar to those at natural reference wetlands. We conclude that WRP and PFWP wetland restorations in this region are meeting federal program-level goals related to the restoration of wildlife habitat, and are contributing to the recovery of SGCN.     

Nordosten der USA

Field trip: The US‐East‐Coast The US‐East‐Coast is a flyway for millions of birds. The Chesapeake Bay with the Delmarva‐Peninsula and her National Wildlife Refuges (NWR) are most attractive destinations to study nature and her history in her habitats for understanding evolution and ecology.     

The surface waters component of the Environmental Monitoring and Assessment Program (EMAP): an overview

The U.S. EPA is developing a new monitoring program, the Environmental Monitoring and Assessment Program (EMAP), to monitor and assess the ecological health of major ecosystems, including surface waters, forests, near-coastal waters, wetlands, agricultural lands, arid lands, and the Great Lakes, in an integrated, systematic manner. The program is designed to operate at regional and national scales, for decades, and to evaluate the extent and condition of entire ecological resources. EMAP has a common sampling framework for all resource types. The frame consists of a systematic grid of about 12,500 points in the conterminous United States that can be subdivided into subgrids of varying densities. A subset of 3,200 40 km² hexagons will be selected for field sampling of surface water resources. A four-year resampling cycle will allow approximately 800 lakes and 800 stream sites to be evaluated annually. Ecological assessments for surface waters will address three environmental values of concern: biotic integrity, fishability, and trophic state. The focus will be on biological assemblages, including fish, zooplankton, macroinvertebrates, birds and diatoms, as response indicators of ecological condition.     

Win-win for wind and wildlife: a vision to facilitate sustainable development

Wind energy offers the potential to reduce carbon emissions while increasing energy independence and bolstering economic development. However, wind energy has a larger land footprint per Gigawatt (GW) than most other forms of energy production, making appropriate siting and mitigation particularly important. Species that require large unfragmented habitats and those known to avoid vertical structures are particularly at risk from wind development. Developing energy on disturbed lands rather than placing new developments within large and intact habitats would reduce cumulative impacts to wildlife. The U.S. Department of Energy estimates that it will take 241 GW of terrestrial based wind development on approximately 5 million hectares to reach 20% electricity production for the U.S. by 2030. We estimate there are ～7,700 GW of potential wind energy available across the U.S., with ～3,500 GW on disturbed lands. In addition, a disturbance-focused development strategy would avert the development of ～2.3 million hectares of undisturbed lands while generating the same amount of energy as development based solely on maximizing wind potential. Wind subsidies targeted at favoring low-impact developments and creating avoidance and mitigation requirements that raise the costs for projects impacting sensitive lands could improve public value for both wind energy and biodiversity conservation.     

国家公园农户对野生动物肇事保险购买意愿及其影响因素——以大熊猫国家公园为例

国家公园内人与野生动物冲突严重,建立野生动物肇事保险机制是减缓冲突的重要举措。以大熊猫国家公园周边社区为例,分析建立国家公园以及农户风险偏好对野生动物肇事保险购买意愿的影响,并探讨冲突程度和制度信任的中介效应。研究结果表明建立国家公园显著增加了农户野生动物肇事保险购买意愿,而农户风险偏好对保险购买意愿会产生负向显著影响。冲突程度和制度信任是重要的中介变量,冲突程度和制度信任均对农户保险购买意愿产生正向显著影响。建立国家公园显著增加了人与野生动物冲突严重程度,进而对保险购买意愿产生正向影响。此外,建立国家公园显著降低了农户制度信任,进而对保险购买意愿产生负向影响。农户风险偏好对野生动物肇事损失程度产生正向显著影响,进而对保险购买意愿产生正向影响。农户风险偏好对制度信任影响并不显著。基于此,研究提出吸纳社会资本参与,拓宽野生动物肇事保险资金来源,开展社区共管、地役权补偿等措施提升社区信任以及建立基于农户自主防护行为的野生动物肇事保险机制等政策建议。     

U.S. regulatory framework for genetic biocontrol of invasive fish

This paper provides an overview of the U.S. regulatory framework governing genetic biocontrol efforts for invasive fish. Genetic biocontrol refers to the intentional release of genetically modified organisms (GMOs) into the environment to control a target population of a non-native species. The terms “genetically modified” and “genetically engineered” are often used interchangeably, despite the scientific distinctions. A GMO is an organism that has had its genetic material altered or modified by humans through any method, including conventional breeding. Genetic engineering, as defined by the Food and Drug Administration (FDA), is the use of recombinant DNA techniques to introduce new characteristics or traits into an organism. GE organisms are therefore a subset of GMOs. As this paper will discuss, existing laws focus on GE organisms raising significant questions as to whether organisms modified without utilizing rDNA techniques fall within the jurisdiction of any federal agency. Under the 1986 Coordinated Framework for Regulation of Biotechnology, three federal agencies have primary responsibility over biotechnology—the Environmental Protection Agency (EPA), the U.S. Department of Agriculture, and the FDA. Because the EPA has exempted biological control agents from regulation as pesticides and no fish species are currently considered plant pests, the FDA is the agency responsible for approving the use of genetically engineered fish for biocontrol. FDA regulates genetically engineered animals through its New Animal Drug Application (NADA) process. The NADA process presents several challenges to effective and transparent regulation of genetic biocontrol, including the FDA’s focus on drug safety, secrecy provisions potentially limiting disclosure of the results of environmental reviews, and the secondary role of the Fish and Wildlife Service, the federal agency with the most experience with invasive species management. In addition, relying on the NADA process creates a significant regulatory gap as NADA approval is only required for GE organisms. The regulatory framework for GMOs created for genetic biocontrol without rDNA technology is unclear and primary responsibility may fall to the states. Given its extensive experience with hatcheries, invasive fish species control, and environmental reviews, the Fish and Wildlife Service (FWS) is the more appropriate agency to review applications for genetic biocontrol. Efforts should be undertaken now, while genetic biocontrol is still in the theoretical stages, to increase the role of the FWS in the permitting process either through formal regulations or more informal mechanisms such as memorandum of understanding.     

DNA-Based Population Demographics of Black Bears in Coastal North Carolina and Virginia

ABSTRACT Noninvasive genetic sampling has become a popular method for obtaining population parameter estimates for black (Ursus americanus) and brown (U. arctos) bears. These estimates allow wildlife managers to develop appropriate management strategies for populations of concern. Black bear populations at Great Dismal Swamp (GDSNWR), Pocosin Lakes (PLNWR), and Alligator River (ARNWR) National Wildlife Refuges in coastal Virginia and North Carolina, USA, were perceived by refuge biologists to be at or above cultural and perhaps biological carrying capacity, but managers had no reliable abundance estimates upon which to base population management. We derived density estimates from 3,150 hair samples collected noninvasively at each of the 3 refuges, using 6–7 microsatellite markers to obtain multilocus genotypes for individual bears. We used Program MARK to calculate population estimates from capture histories at each refuge. We estimated densities using both traditional buffer strip methods and Program DENSITY. Estimated densities were some of the highest reported in the literature and ranged from 0.46 bears/km² at GDSNWR to 1.30 bears/km² at PLNWR. Sex ratios were male-biased at all refuges. Our estimates can be directly utilized by biologists to develop effective strategies for managing and maintaining bears at these refuges, and noninvasive methods may also be effective for monitoring bear populations over the long term.     

Ecological Effects of Metals in Streams on a Defense Materials Processing Site in South Carolina,USA

The Savannah River Site (SRS) is a 780 km² U.S. Department of Energy facility near Aiken, South Carolina, established in 1950 to produce nuclear materials. SRS streams are “integrators” that potentially receive water transportable contaminants from all sources within their drainage basins, necessitating a watershed approach to organize contaminant distribution data and characterize the effects of multiple contaminants on aquatic organisms. This study used several lines-of-evidence to assess the ecological effects of metals in SRS streams, including contaminant exposure models for apex predators and bioassessments of fish and macroinvertebrate assemblages. Concentrations of metals in sediments, fish, and water were elevated in streams affected by SRS operations, but contaminant exposure models for the river otter Lontra Canadensis and belted kingfisher Ceryle alcyon indicated that toxicological reference values were exceeded only by Hg and Al. Macroinvertebrate assemblage structure was unrelated to sediment metal concentrations. Fish assemblage data were inconclusive. This study indicated that (1) modeling studies and field bioassessments provide a complementary basis for addressing the individual and cumulative effects of contaminants, (2) habitat effects must be controlled when assessing contaminant impacts, (3) sensitivity analyses of contaminant exposure models can help to apportion sampling effort, and (4) most individual metals in SRS streams are unlikely to have significant ecological effects.     

Economic incentives for conservation: beekeeping and Saturniidae caterpillar utilization by rural communities

The economic viability of the wildlife based enterprises (bee-keeping and caterpillar utilization) in Malawi is discussed in relation to conventional agricultural enterprises (maize, beans and ground-nuts). A strong incentive emerges for rural people to adopt wildlife management as an adjunct to subsistence agriculture, and therefore, to promote conservation of natural ecosystems and wildlife habitats in the face of growing human population and demand for land. Dependence on agriculture has depleted the wildlife resource outside protected areas and has been less effective in improving the wealth and living standards of most rural people. This study illustrates that the Malawi Department of National Parks and Wildlife needs to introduce economic incentives that integrate biological conservation with economic development for the rural people. The management programme involves the adoption of a rotation burning policy that promotes vegetation coppicing, eases harvesting and promotes high caterpillar yields.     

Comparative changes in density and demography of large herbivores in the Masai Mara Reserve and its surrounding human-dominated pastoral ranches in Kenya

Wildlife habitats in pastoral lands adjoining protected areas in east African savannas are getting progressively degraded, fragmented and compressed by expanding human populations and intensification of land use. To understand the consequences of these influences on wildlife populations, we contrasted the density and demography of 13 wild and three domestic large herbivores between the Masai Mara National Reserve and the adjoining pastoral ranches using aerial surveys conducted in the wet and dry seasons during 1977–2010. Species of different body sizes and feeding styles had different densities between landscapes and seasons. Small-sized herbivores, requiring short, nutritious grasses, and browsers were more abundant in the ranches than the reserve in both seasons. Medium-sized herbivores moved seasonally between landscapes. Larger-bodied herbivores, requiring bulk forage but less susceptible to predation, were more abundant in the reserve than the ranches. The proportions of newborn warthog (Phacochoerus africanus) and juvenile topi (Damaliscus korrigum) were higher in the ranches, with shorter grasses and lower predation risk than in the reserve. These results suggest that pastoral lands adjoining protected areas in African savannas are important as seasonal dispersal and breeding grounds for wild herbivores. However, human population growth and dramatic land use changes are progressively degrading wildlife habitats in pastoral areas, thus restricting the seasonal wildlife dispersal movements between the protected areas and adjoining pastoral lands. Conservation efforts should focus on (1) creating and maintaining functional heterogeneity in protected areas that mimic moderate pastoral grazing conditions to attract small and medium-bodied grazers and (2) securing dispersal areas, including corridors, to ensure continued seasonal large herbivore movements between protected and pastoral systems.     

Wildlife Mortality Investigation and Disease Research: Contributions of the USGS National Wildlife Health Center to Endangered Species Management and Recovery

The U.S. Geological Survey—National Wildlife Health Center (NWHC) provides diagnostic services, technical assistance, applied research, and training to federal, state, territorial, and local government agencies and Native American tribes on wildlife diseases and wildlife health issues throughout the United States and its territories, commonwealth, and freely associated states. Since 1975, >16,000 carcasses and specimens from vertebrate species listed under the Endangered Species Act have been submitted to NWHC for determination of causes of morbidity or mortality or assessment of health/disease status. Results from diagnostic investigations, analyses of the diagnostic database, technical assistance and consultation, field investigation of epizootics, and wildlife disease research by NWHC wildlife disease specialists have contributed importantly to the management and recovery of listed species.     

Evaluation of Reforestation in the Lower Mississippi River Alluvial Valley

Only about 2.8 million ha of an estimated original 10 million ha of bottomland hardwood forests still exist in the Lower Mississippi River Alluvial Valley (LMAV) of the United States. The U.S. Fish and Wildlife Service, the U.S. Forest Service, and state agencies initiated reforestation efforts in the late 1980s to improve wildlife habitat. We surveyed restorationists responsible for reforestation in the LMAV to determine the magnitude of past and future efforts and to identify major limiting factors. Over the past 10 years, 77,698 ha have been reforested by the agencies represented in our survey and an additional 89,009 ha are targeted in the next 5 years. Oaks are the most commonly planted species and bare-root seedlings are the most commonly used planting stock. Problems with seedling availability may increase the diversity of plantings in the future. Reforestation in the LMAV is based upon principles of landscape ecology; however, local problems such as herbivory, drought, and flooding often limit success. Broad-scale hydrologic restoration is needed to fully restore the structural and functional attributes of these systems, but because of drastic and widespread hydrologic alterations and socioeconomic constraints, this goal is generally not realistic. Local hydrologic restoration and creation of specific habitat features needed by some wildlife and fish species warrant attention. More extensive analyses of plantings are needed to evaluate functional success. The Wetland Reserve Program is a positive development, but policies that provide additional financial incentives to landowners for reforestation efforts should be seriously considered.     

Private Lands Programs and Lessons Learned in Illinois

ABSTRACT State wildlife agencies commonly offer private landowners cost-share and technical assistance to improve habitat, but the cost-effectiveness and long-term outcomes of these efforts are rarely evaluated. In 1998, we began a 3-part, statewide evaluation of the Illinois Department of Natural Resources’ (IDNR; USA) Private Land Wildlife Habitat Management Program (hereafter the program) as it functioned from 1986 to 1996. We sent a mail-back questionnaire to IDNR biologists to collect information on their perceptions of the program. We sent a separate mail-back questionnaire to private landholders who participated in the program to ascertain their demographic profile, motivations for participation, and attitudes regarding the program. We also conducted on-site evaluations of private properties that were managed under the guidance of the program. We conducted our study to 1) assess if the program effectively assisted participants in establishing and maintaining wildlife habitat, and 2) determine factors associated with optimal management of wildlife habitat on private lands to refine the program and improve effectiveness. We found significant differences between participants in their land use priorities and motivations for managing wildlife and in the resources available to participants to establish and maintain habitat. Our results indicate that although financial incentives may increase participation in private lands initiatives, improving technical and material assistance to landholders is essential for maintaining quality wildlife habitat over the long-term.     

Effects of Prescribed Fire on Vegetation and Passerine Birds in Northern Mixed-Grass Prairie

ABSTRACT Prescribed fire is used widely to manage grasslands on National Wildlife Refuges and other public lands in the northern Great Plains, but its effects on habitat use or production of wildlife in the region are poorly understood. During 1998–2003, we used point counts to examine effects of prescribed fire on vegetation and passerines in a mixed-grass prairie complex in north-central North Dakota, USA (n = 7 units, each 40–70 ha). Vegetation structure and, to a lesser extent, plant community composition varied with year of study (likely related to changes in annual precipitation) and with number of growing seasons since fire. Fire altered plant structure, especially the amount of residual vegetation, which in turn influenced bird species richness and abundance. The number of indicated pairs for sedge wren (Cistothorus platensis), clay-colored sparrow (Spizella pallida), Le Conte's sparrow (Ammodramus leconteii), Savannah sparrow (Passerculus sandwichensis), and bobolink (Dolichonyx oryzivorus) were lowest during the first postfire growing season but generally increased and stabilized within 2–3 postfire growing seasons. Our results support the premise that grassland passerines are well-adapted to frequent, periodic fires, generally corresponding to those occurring prior to Euro-American settlement of the region. Prescribed fire is important for reducing tree and shrub invasion, restoring biological integrity of plant communities, and maintaining or enhancing populations of grassland-dependent bird species. Managers in the northern mixed-grass prairie region should not be overly concerned about reductions in bird abundances that are limited mostly to the first growing season after fire.     

Using species distribution modeling to set management priorities for mammals in northern Thailand

Rapid deforestation has occurred in northern Thailand and is expected to continue. Thus, identification and protection of sufficient amounts of the highest quality habitat is urgent. Wildlife occurrence data were gathered along wildlife trails and patrolling routes in protected areas and forest patches outside of protected areas. Geographic Information Systems, bio-physical and anthropogenic variables were used to generate suitable habitats for 17 mammal species using maximum entropy theory (MAXENT). Suitable habitats for all species were aggregated, and used to set priorities for wildlife conservation in northern Thailand. In addition, predicted deforestation was overlaid on moderate and high priority areas to determine future wildlife threats and aid decision-making concerning which areas to protect. The results revealed that the total extent of suitable habitats for the studied species covers approximately 37% of the region. Nearly 70% of the total habitat for endangered and vulnerable species is predicted in large and contiguous protected areas. Threatened areas with high biodiversity encompass approximately 1.9% of the region, and 66% of this figure is predicted to occur in existing protected areas. Based on the model outcomes, we recommend reducing human pressures, enhancing the density of prey species and conservation outside protected areas, as well as increasing connectivity of suitable habitats among protected areas that are too small to maintain viable populations in isolation.     

Predators and the public trust

Many democratic governments recognize a duty to conserve environmental resources, including wild animals, as a public trust for current and future citizens. These public trust principles have informed two centuries of U.S.A. Supreme Court decisions and environmental laws worldwide. Nevertheless numerous populations of large‐bodied, mammalian carnivores (predators) were eradicated in the 20th century. Environmental movements and strict legal protections have fostered predator recoveries across the U.S.A. and Europe since the 1970s. Now subnational jurisdictions are regaining management authority from central governments for their predator subpopulations. Will the history of local eradication repeat or will these jurisdictions adopt public trust thinking and their obligation to broad public interests over narrower ones? We review the role of public trust principles in the restoration and preservation of controversial species. In so doing we argue for the essential roles of scientists from many disciplines concerned with biological diversity and its conservation. We look beyond species endangerment to future generations' interests in sustainability, particularly non‐consumptive uses. Although our conclusions apply to all wild organisms, we focus on predators because of the particular challenges they pose for government trustees, trust managers, and society. Gray wolves Canis lupus L. deserve particular attention, because detailed information and abundant policy debates across regions have exposed four important challenges for preserving predators in the face of interest group hostility. One challenge is uncertainty and varied interpretations about public trustees' responsibilities for wildlife, which have created a mosaic of policies across jurisdictions. We explore how such mosaics have merits and drawbacks for biodiversity. The other three challenges to conserving wildlife as public trust assets are illuminated by the biology of predators and the interacting behavioural ecologies of humans and predators. The scientific community has not reached consensus on sustainable levels of human‐caused mortality for many predator populations. This challenge includes both genuine conceptual uncertainty and exploitation of scientific debate for political gain. Second, human intolerance for predators exposes value conflicts about preferences for some wildlife over others and balancing majority rule with the protection of minorities in a democracy. We examine how differences between traditional assumptions and scientific studies of interactions between people and predators impede evidence‐based policy. Even if the prior challenges can be overcome, well‐reasoned policy on wild animals faces a greater challenge than other environmental assets because animals and humans change behaviour in response to each other in the short term. These coupled, dynamic responses exacerbate clashes between uses that deplete wildlife and uses that enhance or preserve wildlife. Viewed in this way, environmental assets demand sophisticated, careful accounting by disinterested trustees who can both understand the multidisciplinary scientific measurements of relative costs and benefits among competing uses, and justly balance the needs of all beneficiaries including future generations. Without public trust principles, future trustees will seldom prevail against narrow, powerful, and undemocratic interests. Without conservation informed by public trust thinking predator populations will face repeated cycles of eradication and recovery. Our conclusions have implications for the many subfields of the biological sciences that address environmental trust assets from the atmosphere to aquifers.     

Fecal genotyping reveals demographic variation in river otters inhabiting a contaminated environment

The deposition and accumulation of persistent contaminants into coastal systems can have lingering negative consequences for wildlife populations and their habitats. Using multi-locus genotyping of non-invasively collected feces, we assessed the effects of such pollution on reproduction, survival, genetic variability, and abundance of river otters (Lontra canadensis) along a gradient of urban–industrial development on southern Vancouver Island, British Columbia, Canada. Genetic analyses indicated a pattern consistent with small-scale structuring, with individuals partitioned into 2 local subpopulations—those identified in the contaminated harbors of southern Vancouver Island and points west (Colwood/Harbors), and those inhabiting uncontaminated habitat east of the harbors (Oak Bay). Genetic and demographic analyses for the 2 clusters provide strong support for the conclusion that, despite contamination concerns, Colwood/Harbors river otters exhibited acceptable levels of survival and successfully reproduced (i.e., high levels of relatedness, high self-recruitment, and high emigration). However, our data indicate that the Colwood/Harbors area constitutes lower quality habitat supporting lower densities of otters, especially during winter, and excess individuals produced in that region emigrate to other areas. Immigration into Colwood/Harbors, however, seems limited, possibly because of behavioral aversion of non-habituated otters to anthropogenic disturbance associated with the harbors and limited optimal otter habitat. Our findings suggest that the effects of chronic contaminant exposure at the population level may be inadvertently mitigated through the behavioral decisions of individuals to avoid poor quality habitats. We conclude that populations of river otters can persist in and around locally contaminated sites if relatively less disturbed and contaminated habitats remain in the vicinity of the affected areas. © 2012 The Wildlife Society.