US National Wildlife Refuges Research Articles

From disappearing climates to climate hubs, the five classes of climate risk for wildlife refuges

Climate change adaptive management strategies for isolated habitats such as wetlands are urgently needed. Conservation areas managed for wildlife refuges can be considered a network, permitting the tracking of current climate conditions within the network under projected future climates. We ask how many classes of temporal climate dynamics exist within a set of 48 refuges that comprise a network of conservation areas. We identified the current-climate conditions of 48 US National Wildlife Refuges using their annual average of minimum temperature and annual precipitation. We then mapped the movement of analogous climates for each refuge from current to future-time periods under four climate projections. We identified distinct types of analog climate dynamics among the network of wildlife refuges that can inform climate-adaptive natural resource planning. We identified five analogous climate categories: (1) disappearing climates; (2) single-analogous climates; (3) multiple-analogous climates; (4) enduring climates; and (5) climate hubs, with some refuges occupying up to three classes. Using four climate projections, we found 10–25 refuges are climatically disappeared; 8–16 whose climate conditions appear in only one other unit; three whose current climate appears in many other refuges; three that are climatically stable; and four that are climate hubs. The relative geographic isolation of refuges makes them particularly appropriate for use as nodes in a network-based climate assessment. The climate classification of the nodes can help inform selection from among multiple refuge management strategies based on their relative analogous climate dynamics. For example, new refuges could be identified to account for species inhabiting climatically disappearing refuges.

Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways.

Warming temperatures associated with climate change can have indirect effects on migratory birds that rely on seasonally available food resources and habitats that vary across spatial and temporal scales. We used two heat-based indices of spring onset, the First Leaf Index (FLI) and the First Bloom Index (FBI), as proxies of habitat change for the period 1901 to 2012 at three spatial scales: the US National Wildlife Refuge System; the four major bird migratory flyways in North America; and the seasonal ranges (i.e., breeding and non-breeding grounds) of two migratory bird species, Blue-winged Warbler (Vermivora cyanoptera) and Whooping Crane (Grus americana). Our results show that relative to the historical range of variability, the onset of spring is now earlier in 76% of all wildlife refuges and extremely early (i.e., exceeding 95% of historical conditions) in 49% of refuges. In all flyways but the Pacific, the rate of spring advance is generally greater at higher latitudes than at lower latitudes. This differential rate of advance in spring onset is most pronounced in the Atlantic flyway, presumably because of a “warming hole” in the southeastern US. Both FLI and FBI have advanced markedly in the breeding ranges–but not the non-breeding ranges–of the two selected bird species, albeit with considerable intra-range variation. Differences among species in terms of migratory patterns and the location and extent of seasonal habitats, as well as shifts in habitat conditions over time, may complicate predictions of the vulnerability of migratory birds to climate change effects. This study provides insight into how differential shifts in the phenology of disparate but linked habitats could inform local- to landscape-scale management strategies for the conservation of migratory bird populations.

Evidence of estrogenic endocrine disruption in smallmouth and largemouth bass inhabiting Northeast U.S. national wildlife refuge waters: A reconnaissance study

Intersex as the manifestation of testicular oocytes (TO) in male gonochoristic fishes has been used as an indicator of estrogenic exposure. Here we evaluated largemouth bass (Micropterus salmoides) or smallmouth bass (Micropterus dolomieu) form 19 National Wildlife Refuges (NWRs) in the Northeast U.S. inhabiting waters on or near NWR lands for evidence of estrogenic endocrine disruption. Waterbodies sampled included rivers, lakes, impoundments, ponds, and reservoirs. Here we focus on evidence of endocrine disruption in male bass evidenced by gonad histopathology including intersex or abnormal plasma vitellogenin (Vtg) concentrations. During the fall seasons of 2008–2010, we collected male smallmouth bass (n=118) from 12 sites and largemouth bass (n=173) from 27 sites. Intersex in male smallmouth bass was observed at all sites and ranged from 60% to 100%; in male largemouth bass the range was 0–100%. Estrogenicity, as measured using a bioluminescent yeast reporter, was detected above the probable no effects concentration (0.73ng/L) in ambient water samples from 79% of the NWR sites. Additionally, the presence of androgen receptor and glucocorticoid receptor ligands were noted as measured via novel nuclear receptor translocation assays. Mean plasma Vtg was elevated (>0.2mg/ml) in male smallmouth bass at four sites and in male largemouth bass at one site. This is the first reconnaissance survey of this scope conducted on US National Wildlife Refuges. The baseline data collected here provide a necessary benchmark for future monitoring and justify more comprehensive NWR-specific studies.

Planning for Adaptation to Climate Change: Lessons from the US National Wildlife Refuge System

US national wildlife refuges have recent, detailed management plans illustrating the state of planning for climate-change adaptation in protected areas. Discussion of and prescriptions for addressing climate change increased in refuge plans between 2005 and 2010 but decreased in 2011. The plans respond to some climate-change impacts on biodiversity and call for monitoring but with little clarity regarding how to act on monitoring results and scant attention to future changes in phenology and community composition. The threats posed by sea-level rise generated the best-developed plan prescriptions. Examples of excellent prescriptions provide models for future planning. Some decision-support tools, such as vulnerability assessments, will improve future planning as they become more available. However, research better targeted at management information gaps is also needed. Region-level coordination, such as through landscape conservation design, offers opportunities for enlarging conservation footprints and improving information generation and sharing.

Invasive Plants in Wildlife Refuges: Coordinated Research with Undergraduate Ecology Courses

Answering large-scale questions in ecology can involve time-consuming data compilation. We show how networks of undergraduate classes can make these projects more manageable and provide an authentic research experience for students. With this approach, we examined the factors associated with plant species richness in US national wildlife refuges. We found that the richness of harmful invasive plants and the richness of native plants were positively correlated in mainland refuges but negatively correlated in island refuges. Nonnative richness and invasive richness were also positively correlated with colonization pressure as indicated by nonnative richness around each refuge. Associations between refuge characteristics and invasive plants varied substantially among regions, with refuge area and habitat diversity important predictors of invasion in some regions but not in others. Our results serve to identify the refuges that are most susceptible to plant invasion and demonstrate the potential value of a new model for education and research integration.

Relationships Hold the Key to Trustworthy and Productive Translational Science: Recommendations for Expanding Community Engagement in Biomedical Research

Good relationships between research institutions and communities are an essential, but often neglected, part of the infrastructure of translational science. In an effort to create greater interest among translational science researchers in cultivating relationships with community members, we report the results of a workshop we convened to learn how relationships vital to research are best created and sustained. We highlight common barriers and challenges that hinder relationships. We also provide recommendations that individual research institutions and teams can use to expand and strengthen their relationships with community members. The improved relationships between universities and communities that could result from their implementation should build greater public trust in biomedical research, lead to a stronger commitment to see it succeed, and engender shared values and commitments that will give rise to new rewards, recognition and admonishment to sustain those values and commitments over time, all of which would facilitate translational science.

Digenean metacercariae of fishes from the lagoon flats of Palmyra Atoll, Eastern Indo-Pacific

Although many studies on the taxonomy of digenean trematodes of marine fishes have been completed in the Eastern Indo-Pacific (EIP) marine ecoregion, only a few have considered metacercarial stages. Here, the results are presented of a taxonomic survey of the digenean metacercariae of fishes from Palmyra Atoll, a remote and relatively pristine US National Wildlife Refuge located 1680km SSW of Hawaii. Up to 425 individual fish were collected, comprising 42 fish species, from the sand flats bordering the lagoon of the atoll. Quantitative parasitological examinations of each fish were performed. Morphological descriptions of the encountered digenean metacercariae are provided, together with their prevalence, mean intensities, host and tissue-use. Up to 33,964 individuals were recovered representing 19 digenean metacercaria species from eight families. The species composition of digeneans in lagoon fishes at Palmyra Atoll is a subset of what has previously been reported for the EIP. Further, the large diversity and abundance of metacercariae reported in this study highlight the utility of including this group in future ecological research in the EIP marine ecoregion.

Predator-Induced Demographic Shifts in Coral Reef Fish Assemblages

In recent years, it has become apparent that human impacts have altered community structure in coastal and marine ecosystems worldwide. Of these, fishing is one of the most pervasive, and a growing body of work suggests that fishing can have strong effects on the ecology of target species, especially top predators. However, the effects of removing top predators on lower trophic groups of prey fishes are less clear, particularly in highly diverse and trophically complex coral reef ecosystems. We examined patterns of abundance, size structure, and age-based demography through surveys and collection-based studies of five fish species from a variety of trophic levels at Kiritimati and Palmyra, two nearby atolls in the Northern Line Islands. These islands have similar biogeography and oceanography, and yet Kiritimati has ∼10,000 people with extensive local fishing while Palmyra is a US National Wildlife Refuge with no permanent human population, no fishing, and an intact predator fauna. Surveys indicated that top predators were relatively larger and more abundant at unfished Palmyra, while prey functional groups were relatively smaller but showed no clear trends in abundance as would be expected from classic trophic cascades. Through detailed analyses of focal species, we found that size and longevity of a top predator were lower at fished Kiritimati than at unfished Palmyra. Demographic patterns also shifted dramatically for 4 of 5 fish species in lower trophic groups, opposite in direction to the top predator, including decreases in average size and longevity at Palmyra relative to Kiritimati. Overall, these results suggest that fishing may alter community structure in complex and non-intuitive ways, and that indirect demographic effects should be considered more broadly in ecosystem-based management.

Long-term movement patterns and trophic ecology of blacktip reef sharks ( Carcharhinus melanopterus) at Palmyra Atoll

Animal movements, residence times, and subsequently foraging strategies, should vary with habitat quality. We used acoustic and satellite telemetry, as well as stable isotopes, to look at movement patterns, macro-scale habitat use, and trophic ecology of blacktip reef sharks, Carcharhinus melanopterus, between two lagoons (eastern and western) at Palmyra Atoll, a US National Wildlife Refuge in the central Pacific. Sharks in the Palmyra lagoons have relatively small home ranges and appear to obtain most of their energy from the lagoon ecosystem. Sharks showed low levels of migration between lagoons over periods of several years, and individuals in the larger western lagoon tended to have longer residence times than those in the smaller eastern lagoon. Furthermore, for sharks in the western lagoon, there was no relationship between total length (TL) and δ 15N, 13C relative isotope concentrations, or a Body Condition index (BC). For sharks in the eastern lagoon, TL was positively related to δ 15N and negatively related to δ 13C and BC. These results suggest that there are low levels of mixing of sharks between lagoons, and these are leading to differences in trophic ecology and potentially foraging success. Although the causative factors behind these differences are unknown, shark home range location can potentially lead to variation in trophic ecology, even over small spatial scales.

Climate Change Adaptation for the US National Wildlife Refuge System

Since its establishment in 1903, the National Wildlife Refuge System (NWRS) has grown to 635 units and 37 Wetland Management Districts in the United States and its territories. These units provide the seasonal habitats necessary for migratory waterfowl and other species to complete their annual life cycles. Habitat conversion and fragmentation, invasive species, pollution, and competition for water have stressed refuges for decades, but the interaction of climate change with these stressors presents the most recent, pervasive, and complex conservation challenge to the NWRS. Geographic isolation and small unit size compound the challenges of climate change, but a combined emphasis on species that refuges were established to conserve and on maintaining biological integrity, diversity, and environmental health provides the NWRS with substantial latitude to respond. Individual symptoms of climate change can be addressed at the refuge level, but the strategic response requires system-wide planning. A dynamic vision of the NWRS in a changing climate, an explicit national strategic plan to implement that vision, and an assessment of representation, redundancy, size, and total number of units in relation to conservation targets are the first steps toward adaptation. This adaptation must begin immediately and be built on more closely integrated research and management. Rigorous projections of possible futures are required to facilitate adaptation to change. Furthermore, the effective conservation footprint of the NWRS must be increased through land acquisition, creative partnerships, and educational programs in order for the NWRS to meet its legal mandate to maintain the biological integrity, diversity, and environmental health of the system and the species and ecosystems that it supports.

The evolution of the US National Wildlife Refuge System and the doctrine of compatibility: C. G. Curtin, Conservation Biology, 7(1), 1993, pp 29–38

The evolution of the US National Wildlife Refuge System and the doctrine of compatibility: C. G. Curtin, Conservation Biology, 7(1), 1993, pp 29–38