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At least 1,477 records · Page 82Linked to original sources
USGS2022

A web-based tool for assessing the condition of benthic diatom assemblages in streams and rivers of the conterminous United States

Benthic diatom assemblages are known to be indicative of water quality but have yet to be widely adopted in biological assessments in the United States due to several limitations. Our goal was to address some of these limitations by developing regional multi-metric indices (MMIs) that are robust to inter-laboratory taxonomic inconsistency, adjusted for natural covariates, and sensitive to a wide range of anthropogenic stressors. We aggregated bioassessment data from two national-scale federal programs and used a data-driven analysis in which all-possible combinations of 2–7 metrics were compared for three measures of performance. After ranking the best-performing MMIs, we selected the final MMIs by evaluating stress-response relations in independent regional datasets of diatom samples paired with measures of several water-quality stressors, including herbicides and streamflow flashiness. Each regional MMI performed well at calibration sites and represented diverse aspects of the structure and function of diatom communities. Most metrics included in the best MMIs were modeled to account for natural variation including climate, topography, soil characteristics, lithology, and groundwater influence on streamflow. MMI performance improved with higher numbers of component metrics, but this effect diminished beyond six metrics. Component metrics of MMIs were associated with a broad suite of measured stressors in every region, including salinity, nutrients, herbicides, and streamflow flashiness. We provide a web-based software application that allows users in the conterminous United States to apply our MMIs to their own datasets and compare MMI scores from their sites to a broader regional context.

Ecological Indicators↗
USGS2018

Time-varying predatory behavior is primary predictor of fine-scale movement of wildland-urban cougars

Background While many species have suffered from the detrimental impacts of increasing human population growth, some species, such as cougars ( Puma concolor ), have been observed using human-modified landscapes. However, human-modified habitat can be a source of both increased risk and increased food availability, particularly for large carnivores. Assessing preferential use of the landscape is important for managing wildlife and can be particularly useful in transitional habitats, such as at the wildland-urban interface. Preferential use is often evaluated using resource selection functions (RSFs), which are focused on quantifying habitat preference using either a temporally static framework or researcher-defined temporal delineations. Many applications of RSFs do not incorporate time-varying landscape availability or temporally-varying behavior, which may mask conflict and avoidance behavior. Methods Contemporary approaches to incorporate landscape availability into the assessment of habitat selection include spatio-temporal point process models, step selection functions, and continuous-time Markov chain (CTMC) models; in contrast with the other methods, the CTMC model allows for explicit inference on animal movement in continuous-time. We used a hierarchical version of the CTMC framework to model speed and directionality of fine-scale movement by a population of cougars inhabiting the Front Range of Colorado, U.S.A., an area exhibiting rapid population growth and increased recreational use, as a function of individual variation and time-varying responses to landscape covariates. Results We found evidence for individual- and daily temporal-variability in cougar response to landscape characteristics. Distance to nearest kill site emerged as the most important driver of movement at a population-level. We also detected seasonal differences in average response to elevation, heat loading, and distance to roads. Motility was also a function of amount of development, with cougars moving faster in developed areas than in undeveloped areas. Conclusions The time-varying framework allowed us to detect temporal variability that would be masked in a generalized linear model, and improved the within-sample predictive ability of the model. The high degree of individual variation suggests that, if agencies want to minimize human-wildlife conflict management options should be varied and flexible. However, due to the effect of recursive behavior on cougar movement, likely related to the location and timing of potential kill-sites, kill-site identification tools may be useful for identifying areas of potential conflict.

Colorado↗
USGS2016

Flow regime effects on mature Populus fremontii (Fremont cottonwood) productivity on two contrasting dryland river floodplains

I compared riparian cottonwood ( Populus fremontii ) productivity-discharge relationships in a relictual stand along the highly regulated Green River and in a naturally functioning stand along the unregulated Yampa River in semiarid northwest Colorado. I used multiple regression to model flow effects on annual basal area increment (BAI) from 1982 to 2011, after removing any autocorrelation present. Each BAI series was developed from 20 trees whose mean size (67 cm diameter at breast height [DBH]) was equivalent in the two stands. BAI was larger in the Yampa River stand except in 2 y when defoliating leaf beetles were present there. I found no evidence for a Yampa flood-magnitude threshold above which BAI declined. Flow variables explained ∼45% of residual BAI variability, with most explained by current-year maximum 90-d discharge (Q M90 ) in the Yampa River stand and by a measure of the year-to-year change in Q M90 in the Green River stand. The latter reflects a management-imposed ceiling on flood magnitude—Flaming Gorge Dam power plant capacity—infrequently exceeded during the study period. BAI in the relictual stand began to trend upward in 1992 when flows started to mimic a natural flow regime. Mature Fremont cottonwoods appear to be ecologically resilient. Their productivity along regulated rivers might be optimized using multiyear environmental flow designs.

Southwestern Naturalist↗
USGS2012

Biological assessment of environmental flows for Oklahoma

Large-scale patterns in fish assemblage structure and functional groups are influenced by alterations in streamflow regime. In this study, we defined an objective threshold for alteration for Oklahoma streams using a combination of the expected range of 27 flow indices and a discriminant analysis to predict flow regime group. We found that fish functional groups in reference flow conditions had species that were more intolerant to flow alterations and preferences for stream habitat and faster flowing water. In contrast, altered sites had more tolerant species that preferred lentic habitat and slower water velocity. Ordination graphs of the presence and functional groups of species revealed an underlying geographical pattern roughly conforming to ecoregions, although there was separation between reference and altered sites within the larger geographical framework. Additionally, we found that reservoir construction and operation significantly altered fish assemblages in two different systems, Bird Creek in central Oklahoma and the Kiamichi River in southeastern Oklahoma. The Bird Creek flow regime shifted from a historically intermittent stream to one with stable perennial flows, and changes in fish assemblage structure covaried with changes in all five components of the flow regime. In contrast, the Kiamichi River flow regime did not change significantly for most flow components despite shifts in fish assemblage structure; however, most of the species associated with shifts in assemblage structure in the Kiamichi River system were characteristic of lentic environments and were likely related more to proximity of reservoirs in the drainage system than changes in flow. The spatial patterns in fish assemblage response to flow alteration, combined with different temporal responses of hydrology and fish assemblage structure at sites downstream of reservoirs, indicate that interactions between flow regime and aquatic biota vary depending on ecological setting. This supports the notion that regional variation in natural flow regimes could affect the development of flow recommendations.

Oklahoma↗
USGS2014

Guild-specific responses of avian species richness to LiDAR-derived habitat heterogeneity

Ecological niche theory implies that more heterogeneous habitats have the potential to support greater biodiversity. Positive heterogeneity-diversity relationships have been found for most studies investigating animal taxa, although negative relationships also occur and the scale dependence of heterogeneity-diversity relationships is little known. We investigated multi-scale, heterogeneity-diversity relationships for bird communities in a semi-arid riparian landscape, using airborne LiDAR data to derive key measures of structural habitat complexity. Habitat heterogeneity-diversity relationships were generally positive, although the overall strength of relationships varied across avian life history guilds (R 2 range: 0.03–0.41). Best predicted were the species richness indices of cavity nesters, habitat generalists, woodland specialists, and foliage foragers. Heterogeneity-diversity relationships were also strongly scale-dependent, with strongest associations at the 200-m scale (4 ha) and weakest associations at the 50-m scale (0.25 ha). Our results underscore the value of LiDAR data for fine-grained quantification of habitat structure, as well as the need for biodiversity studies to incorporate variation among life-history guilds and to simultaneously consider multiple guild functional types (e.g. nesting, foraging, habitat). Results suggest that certain life-history guilds (foliage foragers, cavity nesters, woodland specialists) are more susceptible than others (ground foragers, ground nesters, low nesters) to experiencing declines in local species richness if functional elements of habitat heterogeneity are lost. Positive heterogeneity-diversity relationships imply that riparian conservation efforts need to not only provide high-quality riparian habitat locally, but also to provide habitat heterogeneity across multiple scales.

California;Nevada↗
USGS2009

Biological soil crusts exhibit a dynamic response to seasonal rain and release from grazing with implications for soil stability

In Northern Mexico, long-term grazing has substantially degraded semiarid landscapes. In semiarid systems, ecological and hydrological processes are strongly coupled by patchy plant distribution and biological soil crust (BSC) cover in plant-free interspaces. In this study, we asked: 1) how responsive are BSC cover/composition to a drying/wetting cycle and two-year grazing removal, and 2) what are the implications for soil erosion? We characterized BSC morphotypes and their influence on soil stability under grazed/non-grazed conditions during a dry and wet season. Light- and dark-colored cyanobacteria were dominant at the plant tussock and community level. Cover changes in these two groups differed after a rainy season and in response to grazing removal. Lichens with continuous thalli were more vulnerable to grazing than those with semi-continuous/discontinuous thalli after the dry season. Microsites around tussocks facilitated BSC colonization compared to interspaces. Lichen and cyanobacteria morphotypes differentially enhanced resistance to soil erosion; consequently, surface soil stability depends on the spatial distribution of BSC morphotypes, suggesting soil stability may be as dynamic as changes in the type of BSC cover. Longer-term spatially detailed studies are necessary to elicit spatiotemporal dynamics of BSC communities and their functional role in biotically and abiotically variable environments. ?? 2009 Elsevier Ltd.

Journal of Arid Environments↗
USGS2023

Full-service hotels, convenience stores, or fire escapes? Evaluating the functional role of stopover sites for Neotropical migrants following passage across the Gulf of Mexico in autumn

Nearctic Neotropical migratory songbirds incur the highest mortality during migration. En-route, songbirds rely on a network of stopover sites to rest, refuel, and/or seek refuge during poor weather. Conservation strategies prioritize protection of sites that best meet these needs. However, the specific function of a stopover site is expected to vary in relation to factors, such as geographic location, surrounding landscape, and weather. To identify sites with the highest conservation value for migratory songbirds, a conceptual framework was independently developed to classify sites into three functional categories based on their geographic and landscape features: fire escapes, convenience stores, and full-service hotels. The few attempts to empirically validate this framework have focused on temperate stopover sites. We evaluated the framework by testing the hypothesis that a site’s geographic and landscape characteristics can predict its function. We used capture and radio-tracking data at an island and mainland site in the Yucatan Peninsula, Mexico to quantify mean and variance in daily capture rate, body condition, stopover duration, and departure behavior during autumn, with a focus on four species: Swainson’s Thrush (Catharus ustulatus), Red-eyed Vireo (Vireo olivaceus), Gray Catbird (Dumetella carolinensis), and Prothonotary Warbler (Protonotaria citrea). Our results supported our predictions that the island functions as a fire escape, providing refuge for very high numbers of birds after encountering crosswinds or headwinds over the Gulf of Mexico, and the mainland forest site serves as a full-service hotel. The framework provides valuable insight for strategic conservation planning and management of stopover sites for songbirds. We suggest future studies evaluate the framework’s application to non-forest bird species. Additionally, we encourage collaborative efforts to consolidate and integrate tracking data, capture data from migration banding stations, and radar-based bird density estimates across a broad geography to test the framework’s ability to inform conservation planning across species’ full migratory range.

Avian Conservation and Ecology↗
USGS2007

Ammonia-oxidizing bacterial community composition in estuarine and oceanic environments assessed using a functional gene microarray

The relationship between environmental factors and functional gene diversity of ammonia-oxidizing bacteria (AOB) was investigated across a transect from the freshwater portions of the Chesapeake Bay and Choptank River out into the Sargasso Sea. Oligonucleotide probes (70-bp) designed to represent the diversity of ammonia monooxygenase (amoA) genes from Chesapeake Bay clone libraries and cultivated AOB were used to construct a glass slide microarray. Hybridization patterns among the probes in 14 samples along the transect showed clear variations in amoA community composition. Probes representing uncultivated members of the Nitrosospira-like AOB dominated the probe signal, especially in the more marine samples. Of the cultivated species, only Nitrosospira briensis was detected at appreciable levels. Discrimination analysis of hybridization signals detected two guilds. Guild 1 was dominated by the marine Nitrosospira-like probe signal, and Guild 2???s largest contribution was from upper bay (freshwater) sediment probes. Principal components analysis showed that Guild 1 was positively correlated with salinity, temperature and chlorophyll a concentration, while Guild 2 was positively correlated with concentrations of oxygen, dissolved organic carbon, and particulate nitrogen and carbon, suggesting that different amoA sequences represent organisms that occupy different ecological niches within the estuarine/marine environment. The trend from most diversity of AOB in the upper estuary towards dominance of a single type in the polyhaline region of the Bay is consistent with the declining importance of AOB with increasing salinity, and with the idea that AO-Archaea are the more important ammonia oxidizers in the ocean.

Environmental Microbiology↗
USGS2023

Changes in abiotic drivers of green sea urchin demographics following the loss of a keystone predator

Sea urchin population demographics can respond to changes in keystone species abundances, with the magnitude of these responses varying depending on environmental influences. In this study, sea urchin populations were surveyed across 15 Aleutian archipelago islands over a 30-year period to understand how patterns of sea urchin demography (density, biomass, and size structure) varied through different ecological regimes that were caused by changes in the abundance of sea otters, a keystone species in this system. To examine long-term changes in sea urchin demographics, four time periods across the recent decline of sea otters were examined: during sea otter presence (1987-1994), nearing absence at the end of the decline (1997-2000), 10 years postdecline (2008-2010), and 15-20 years following the loss of sea otters from the ecosystem (2014-2017). Our results show that when sea otters were broadly present, sea urchin demographics were generally similar across the archipelago, with few urchins that had large-sized bodies. During this time, bottom-up environmental controls were muted relative to top-down forces from keystone predation. However, as sea otters declined and remained absent from the system, abiotic factors became more influential on sea urchin biomass, density, and size structure. In particular, differences among island groups during these periods were correlated with variation in ocean temperature, bathymetric complexity, and habitat availability. Sea urchin recruitment also varied among island groups, corresponding to ecoregions delineated by oceanic passes across the archipelago. The functional extinction of sea otters revealed an increasing influence of abiotic forcing in the absence of top-down control. This study further highlights the importance of understanding how keystone predators regulate herbivore demographics.

Alaska↗
USGS2022

Integrating principles and tools of decision science into value-driven watershed planning for compensatory mitigation

Several environmental policies strive to restore impaired ecosystems and could benefit from a consistent and transparent process — co-developed with key stakeholders — to prioritize impaired ecosystems for restoration activities. The Clean Water Act, for example, establishes reallocation mechanisms to transfer ecosystem services from sites of disturbance to compensation sites to offset aquatic resource functions that are unavoidably lost through land development. However, planning for the prioritization of compensatory mitigation areas is often hampered by decision-making processes that fall into a myopic decision frame because they are not co-produced with stakeholders. In this study, we partnered with domain experts from the North Carolina Division of Mitigation Services (NCDMS) to co-develop a real-world decision framework to prioritize catchments by potential for the development of mitigation projects following principles of a structured decision-making process and knowledge co-production. Following an iterative decision analysis cycle, domain experts revised foundational components of the decision framework and progressively added complexity and realism as they gained additional insights or more information became available. Through the course of facilitated in-person and remote interactions, the co-development of a decision framework produced three main ‘breakthroughs’ from the perspective of the stakeholder group: a) recognition of the problem as a multi-objective decision driven by several values in addition to biogeophysical goals (e.g., functional uplift; restoring or enhancing lost functionality of ecosystems), b) that the decision comprises a linked and sequential planning-to-implementation process, and c) future risk associated with land-use and climate change must be considered. We also present an interactive tool for ‘on-the-fly’ assessment of alternatives and tradeoff analysis, allowing domain experts to quickly test, react to, and revise prioritization strategies. The decision framework described in this study is not limited to the prioritization of compensatory mitigation activities across North Carolina, but rather serves as a framework to prioritize a wide range of restoration, conservation, and resource allocation activities in similar environmental contexts across the nation.

Ecological Applications↗
USGS2017

Response of fish population dynamics to mitigation activities in a large regulated river

Extensive water development in large rivers has precipitated many negative ecological effects on native fish populations. Mitigation for such development often focuses on restoring biological integrity through remediation of the physical and chemical properties of regulated rivers. However, evaluating and defining the success of those programs can be difficult. We modeled the influence of mitigation-related environmental factors on growth and recruitment of two ecologically important native fish species (Largescale Sucker Catostomus macrocheilus and Mountain Whitefish Prosopium williamsoni ) in the Kootenai River, Idaho. Artificial nutrient (phosphorus) addition best predicted the variability in annual growth of both species. Nutrient addition was positively related to Largescale Sucker growth but negatively related to Mountain Whitefish growth. The best model explained 82% of the annual variability in incremental growth for Largescale Suckers and 61% of the annual variability for Mountain Whitefish. Year-class strength of Largescale Suckers was not closely related to any of the environmental variables evaluated; however, year-class strength of Mountain Whitefish was closely associated with nutrient addition, discharge, and temperature. Most research has focused on biotic assemblages to evaluate the effects of mitigation activities on fishes, but there is an increased need to identify the influence of rehabilitation activities on fish population dynamics within those assemblages. Here, we demonstrate how fish growth can serve as an indicator of rehabilitation success in a highly regulated large river. Future fish restoration projects can likely benefit from a change in scope and from consideration of an evaluation framework involving the response of population rate functions to mitigation.

Idaho↗
USGS2025

DNA metabarcoding of biocrust lichen-forming fungi detects responses to disturbance and invasion

Biocrusts dominated by bryophytes and lichens perform important functions in dryland ecosystems but monitoring these communities can be cost prohibitive over broad scales. We explored DNA metabarcoding as a potential tool for monitoring biocrust lichen communities at a site in Washington (U.S.A.) that had already been surveyed for lichen diversity and community composition. We developed a DNA reference library using the internal transcribed spacer (ITS) region from specimens collected in the study area. We also visually estimated the abundance of lichen species or groups in 22 plots spanning a range of wildfire history and invasion by the exotic annual grass Bromus tectorum . At these plots, we collected bulk lichen community samples for metabarcoding using two approaches: small sample dishes and combined biocrust fragments collected using tweezers from all species observed. We used PacBio sequencing to simultaneously generate ITS barcode sequences for all lichen-forming fungi (LFF) present in the bulk samples, clustering similar sequences into operational taxonomic units (OTUs). Lichen communities detected visually and using DNA metabarcoding both captured a reduction of biocrust diversity and change in community composition related to the abundance of B. tectorum , suggesting that metabarcoding was able to identify the same dominant ecological pattern in biocrust lichens as visual sampling. The tweezer sampling approach captured on average 12.3 more OTUs than the dish approach and some taxa were more consistently detected by one approach or the other. After using the specimen DNA reference library to identify species associated with LFF OTUs, we determined that metabarcoding and visual sampling detected overlapping but different lichen species. Metabarcoding failed to detect common collected taxa, including: Arthonia glebosa, Candelariella spp ., Enchylium tenax, Lecanora muralis, Lecidella spp ., Leptochidium albociliatum, Massalongia carnosa, and Trapeliopsis glaucopholis. However, metabarcoding detected OTUs not visually observed in the genera Elixia, Lecanora, Lecanoropsis, Bacidina, Pyrenodesmia, Xanthocarpia, Trapelia, Verrucaria, and Verruculopsis . Furthermore, metabarcoding identified greater OTU diversity than expected within Diploschistes muscorum, Trapeliopsis bisorediata, and Trapeliopsis steppica . Our results suggest that metabarcoding alone or combined with visual methods could be a useful approach for monitoring biocrust lichen communities and their response to disturbance, invasion, and potential restoration.

Washington↗
USGS2021

Age-related reproductive performance of the Adélie penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy

Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

Beaufort Island ,Ross Island↗
USGS2023

A recruitment niche framework for improving seed-based restoration

As larger tracts of land experience degradation, seed-based restoration (SBR) will be a primary tool to reestablish vegetation and ecosystem function. SBR has advanced in terms of technical and technological approaches, yet plant recruitment remains a major barrier in some systems, notably drylands. There is an unmet opportunity to test science-based approaches to seed mix design and application, based not only on diversity or local provenance, but on the unique recruitment strategies of species. We lay out a framework that uses a quantitative representation of species' recruitment niches to match them to targeted goals (e.g. drought or invasion resistance) and methods (e.g. precision tools and technologies) in SBR. We first describe how to quantify the recruitment niche with seed and seedling traits tied to observed recruitment responses to environmental factors. We then show how a quantified recruitment niche framework can serve as the foundation to address three major restoration challenges: (1) designing forward-looking seed mixes that increase resilience to future climate and disturbance, (2) accounting for natural recovery in SBR planning, and (3) applying precision seeding practices to maximize restoration success. Finally, we demonstrate these ideas with existing data and discuss key challenges to adoption in SBR practice. While the ideas in this framework are based in ecological theory, they will require substantial testing and refinement by scientists engaged in SBR efforts. If this framework is integrated into research agendas, we believe it has the potential to unify and advance diverse elements of seed-based restoration ecology and improve restoration outcomes.

Restoration Ecology↗
USGS2015

Effects of harvesting forest biomass on water and climate regulation services: A synthesis of long-term ecosystem experiments in eastern North America

Demand for woody biomass fuels is increasing amidst concerns about global energy security and climate change, but there may be negative implications of increased harvesting for forest ecosystem functions and their benefits to society (ecosystem services). Using new methods for assessing ecosystem services based on long-term experimental research, post-harvest changes in ten potential benefits were assessed for ten first-order northern hardwood forest watersheds at three long-term experimental research sites in northeastern North America. As expected, we observed near-term tradeoffs between biomass provision and greenhouse gas regulation, as well as tradeoffs between intensive harvest and the capacity of the forest to remediate nutrient pollution. In both cases, service provision began to recover along with the regeneration of forest vegetation; in the case of pollution remediation, the service recovered to pre-harvest levels within 10 years. By contrast to these two services, biomass harvesting had relatively nominal and transient impacts on other ecosystem services. Our results are sensitive to empirical definitions of societal demand, including methods for scaling societal demand to ecosystem units, which are often poorly resolved. Reducing uncertainty around these parameters can improve confidence in our results and increase their relevance for decision-making. Our synthesis of long-term experimental studies provides insights on the social-ecological resilience of managed forest ecosystems to multiple drivers of change.

Hubbard Brook Experimental Forest, Neversink River↗
USGS2015

When Siberia came to the Netherlands: The response of continental black-tailed godwits to a rare spring weather event

Summary Extreme weather events have the potential to alter both short- and long-term population dynamics as well as community- and ecosystem-level function. Such events are rare and stochastic, making it difficult to fully document how organisms respond to them and predict the repercussions of similar events in the future. To improve our understanding of the mechanisms by which short-term events can incur long-term consequences, we documented the behavioural responses and fitness consequences for a long-distance migratory bird, the continental black-tailed godwit Limosa limosa limosa , resulting from a spring snowstorm and three-week period of record low temperatures. The event caused measurable responses at three spatial scales – continental, regional and local – including migratory delays (+19 days), reverse migrations (>90 km), elevated metabolic costs (+8·8% maintenance metabolic rate) and increased foraging rates (+37%). There were few long-term fitness consequences, however, and subsequent breeding seasons instead witnessed high levels of reproductive success and little evidence of carry-over effects. This suggests that populations with continued access to food, behavioural flexibility and time to dissipate the costs of the event can likely withstand the consequences of an extreme weather event. For populations constrained in one of these respects, though, extreme events may entail extreme ecological consequences.

Journal of Animal Ecology↗
USGS2011

Patterns in young-of-year smallmouth bass microhabitat use in multiple stream segments with contrasting land uses

Young-of-the-year (YOY) smallmouth bass, Micropterus dolomieu Lacepede, were evaluated in streams from eight catchments with two contrasting land uses to determine their use of microhabitats under a variety of stream conditions. Step-wise discriminant function analyses revealed patterns of habitat use by discriminating used from available microhabitat conditions. Velocity was significant in 88% of streams sampled, whereas depth was significant in only the smallest stream in the forest-dominated catchments and 75% of stream segments located in pasture-dominated catchments. Mean velocities used by YOY bass were lower than available velocities, and mean depths used were greater than mean availability in all cases. Substrata varied significantly with availability in different stream segments. Error rates associated with classification ranged from 5 to 39%. Results indicate that YOY smallmouth bass are somewhat opportunistic, but use low-velocity habitats in most cases and deeper water when streams are impacted by pasture land use and associated physical changes.

Fisheries Management and Ecology↗
USGS2017

Assessing pollinator habitat services to optimize conservation programs

Pollination services have received increased attention over the past several years, and protecting foraging area is beginning to be reflected in conservation policy. This case study considers the prospects for doing so in a more analytically rigorous manner, by quantifying the pollination services for sites being considered for ecological restoration. The specific policy context is the Conservation Reserve Program (CRP), which offers financial and technical assistance to landowners seeking to convert sensitive cropland back to some semblance of the prairie (or, to a lesser extent, forest or wetland) ecosystem that preceded it. Depending on the mix of grasses and wildflowers that are established, CRP enrollments can provide pollinator habitat. Further, depending on their location, they will generate related services, such as biological control of crop pests, recreation, and aesthetics. While offers to enroll in CRP compete based on cost and some anticipated benefits, the eligibility and ranking criteria do not reflect these services to a meaningful degree. Therefore, we develop a conceptual value diagram to identify the sequence of steps and associated models and data necessary to quantify the full range of services, and find that critical data gaps, some of which are artifacts of policy, preclude the application of benefit-relevant indicators (BRIs) or monetization. However, we also find that there is considerable research activity underway to fill these gaps. In addition, a modeling framework has been developed that can estimate field-level effects on services as a function of landscape context. The approach is inherently scalable and not limited in geographic scope, which is essential for a program with a national footprint. The parameters in this framework are sufficiently straightforward that expert judgment could be applied as a stopgap approach until empirically derived estimates are available. While monetization of benefit-relevant indicators of yield changes (crop and honey) and of habitat benefits due to enhanced pollination and pest bio-control services would be relatively straightforward, the merits of proceeding when other services cannot be valued now should be carefully considered.

Report↗