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USGS2026

Adaptation and response in drylands: A dryland research agenda and campaign strategy

Dryland ecosystems cover 41% of Earth's land surfaces, account for 44% of cultivated lands and 60% of food sources, and make large contributions to the global water and carbon cycles. However, these ecosystems are experiencing unprecedented extremes including heatwaves, floods, and droughts as well as hotter temperatures and often declining water resource availability. These ecosystems are some of the most challenging to monitor given their high temporal variability with rapid response to their environment as well as vast spatial variability with intermixing of different plant species and life forms amongst bare soil coverage. The Adaptation and Response in Drylands (ARID) campaign was selected by National Aeronautics and Space Administration (NASA) as a scoping study to develop a research agenda for a dryland field campaign. Here, we detail our ARID science research agenda and implementation plan that were developed based on an extensive community engagement effort in over 160 events with over a thousand scientists, land managers, and Tribal communities between 2023 and 2024. The selected science themes cover drought and climate variability, ecosystem structure, function, and biodiversity, carbon cycle interannual variability and trends, and social ecological systems (land management and adaptation). We then detail our remote sensing, modeling, and field-based strategies to capture high temporal and high spatial resolution processes. Finally, our implementation strategy is presented which includes focus area selections in a core intensive western U.S. domain and distributed international domains. This strategy includes our overarching guiding principles of using multi-temporal airborne acquisitions and super sites as well as enhancing land management in co-development with end-user partners. While originally developed for NASA, our ARID report creates a blueprint for any future dryland field campaign, at any scale, that can be implemented widely for foundational and applied science objectives.

Global Change Biology↗

USGS2022

Contaminant fluxes across ecosystems mediated by aquatic insects

Metals and organic contaminants in aquatic systems affect the coupling of aquatic and terrestrial ecosystems through two pathways: contaminant-induced effects on insect emergence and emergence-induced contaminant transfer. Consequently, the impact of aquatic contaminants on terrestrial ecosystems can be driven by modifications in the quantity and quality of adult aquatic insects serving as prey or contaminants entering terrestrial food webs as part of the diet of terrestrial predators. Here, we provide an overview of recent advances in the field, separating metals from organic contaminants due to their differential propensity to bioaccumulate and thus their potential contribution to either of the two pathways. Finally, this review highlights the knowledge gap in the relative impact of these pathways on terrestrial insectivores.

Current Opinion in Insect Science↗

USGS2015

Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves ( Canis lupus )

Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves ( Canis lupus ) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to be Toxascaris leonina . Taenia species present included T. krabbei and T. hydatigena . Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from < 1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ 13 C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host.

Science of the Total Environment↗

USGS2021

On the human appropriation of wetland primary production

Humans are changing the Earth's surface at an accelerating pace, with significant consequences for ecosystems and their biodiversity. Landscape transformation has far-reaching implications including reduced net primary production (NPP) available to support ecosystems, reduced energy supplies to consumers, and disruption of ecosystem services such as carbon storage. Anthropogenic activities have reduced global NPP available to terrestrial ecosystems by nearly 25%, but the loss of NPP from wetland ecosystems is unknown. We used a simple approach to estimate aquatic NPP from measured habitat areas and habitat-specific areal productivity in the largest wetland complex on the USA west coast, comparing historical and modern landscapes and a scenario of wetland restoration. Results show that a 77% loss of wetland habitats (primarily marshes) has reduced ecosystem NPP by 94%, C (energy) flow to herbivores by 89%, and detritus production by 94%. Our results also show that attainment of habitat restoration goals could recover 12% of lost NPP and measurably increase carbon flow to consumers, including at-risk species and their food resources. This case study illustrates how a simple approach for quantifying the loss of NPP from measured habitat losses can guide wetland conservation plans by establishing historical baselines, projecting functional outcomes of different restoration scenarios, and establishing performance metrics to gauge success.

California↗

USGS2024

Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA

Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by various source inputs to the lake and complex biogeochemistry. Here, we leverage Hg and Pb stable isotopes to track relative changes in metal source contributions to Great Salt Lake over time. Mercury and Pb concentrations increase in sediments deposited after 1920 and peak between 1965 and 1995, following closure of several local smelters and the onset of increased emission controls. The nominal associations above are confirmed via Hg stable isotopes in pre-1920 background sediments, which reflect atmospheric inputs from regional and global origin, whereas Hg and Pb stable isotopes together indicate that elevated metal concentrations in mid-late 20th century sediments reflect increased mining/smelting inputs. The observed minimal rebound towards pre-1920 Pb isotope signatures in 21st century sediments indicates that mining/smelting inputs, though reduced, remain a primary source of Pb to Great Salt Lake. In contrast, the more pronounced rebound of Hg stable isotope signatures to pre-1920 values indicate a greater contribution of atmospheric inputs of regional/global origin to current Hg inputs, though Hg concentrations are ∼10 times greater than pre-1920 background values due to global increases in atmospheric Hg concentrations or possibly slow recovery from local contamination. The importance of regional/global Hg sources to the system suggests that reductions in Hg bioaccumulation in the open water food webs of Great Salt Lake are more dependent on national and global reductions in Hg emissions and management strategies to limit methylmercury production within system. This work highlights the utility of using coupled Hg and Pb stable isotope values to assess trace metal pollution sources and pathways in aquatic systems.

Utah↗

USGS2017

Ecological change drives a decline in mercury concentrations in southern Beaufort Sea polar bears

We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g –1 dry weight (mean: 3.5 ± 0.2 μg g –1 ). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-of-the-year ≈ 2 year old dependent cubs. No variation was observed between spring and fall samples. For spring-sampled adults, THg concentrations declined by 13% per year, contrasting recent trends observed for other Western Hemispheric Arctic biota. Concentrations also declined by 15% per year considering adult males only, while a slower, nonsignificant decrease of 4.4% per year was found for adult females. Lower THg concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position food resources consumed. Because BMI and diet were related, and the relationship to THg was strongest for BMI, trends were re-evaluated adjusting for BMI as the covariate. The adjusted annual decline was not significant. These findings indicate that changes in foraging ecology, not declining environmental concentrations of mercury, are driving short-term declines in THg concentrations in southern Beaufort Sea polar bears.

Alaska↗

USGS2014

The role of tidal marsh restoration in fish management in the San Francisco Estuary

Tidal marsh restoration is an important management issue in the San Francisco Estuary (estuary). Restoration of large areas of tidal marsh is ongoing or planned in the lower estuary (up to 6,000 ha, Callaway et al. 2011). Large areas are proposed for restoration in the upper estuary under the Endangered Species Act biological opinions (3,237 ha) and the Bay Delta Conservation Plan (26,305 ha). In the lower estuary, tidal marsh has proven its value to a wide array of species that live within it (Palaima 2012). In the Sacramento–San Joaquin Delta (Delta), one important function ascribed to restoration of freshwater tidal marshes is that they make large contributions to the food web of fish in open waters (BDCP 2013). The Ecosystem Restoration Program ascribed a suite of ecological functions to tidal marsh restoration, including habitat and food web benefits to native fish (CDFW 2010). This background was the basis for a symposium, Tidal Marshes and Native Fishes in the Delta: Will Restoration Make a Difference? held at the University of California, Davis, on June 10, 2013. This paper summarizes conclusions the authors drew from the symposium.

California↗

USGS2022

Workshops report for mesophotic and deep benthic community fish, mobile invertebrates, sessile invertebrates and infauna

Two workshops with subject matter experts in the appropriate fields, were held in November and December 2021 to elicit guidance and feedback from the broader mesophotic and deep benthic scientific community. These workshops focused on best practices/approaches and identifying data gaps relative to habitat assessment and evaluation goals of the Mesophotic and Deep Benthic Community (MDBC) restoration portfolio. The first workshop was a combined effort of the Habitat Assessment and Evaluation (HAE) Project Team and the Deepwater Horizon (DWH) Program. Industrial Economics, Inc. (IEc) provided extensive workshop planning, organizing, execution, and facilitation support during all stages of the workshop. Based on a questionnaire sent to scientists in August, 2021, the workshop focused on fish and mobile invertebrate habitat associations, abundance trends, community metrics, and food web functionality. Topical presentations and discussions focused not only on demersal fish and mobile invertebrates that are directly associated with mesophotic and deep benthic habitats, but also considered water column species and communities that benefit from these habitats more broadly. The second workshop, intended to complement the first workshop, focused on identifying best practices and critical information gaps for key community metrics, larval dispersal modeling, connectivity, effects and variability of environmental parameters, and recovery trajectories of corals, infauna, and other sessile invertebrates. Through literature review, internal HAE scientists considered these topics to be critical for restoration success. Products from the literature review included topical summaries (see Appendix B) that summarized the current state-of-the-science and provided the framework for the workshop. Information generated from the workshops will assist the MDBC HAE Project, and more broadly the DWH Program, identify data gaps and develop a suite of best practices for restoration activities.

DWH MDBC Summary Report↗

USGS2025

Assessing microplastics, per- and polyfluoroalkyl substances (PFAS), and other contaminants of global concern in wadable agricultural streams

Microplastics, per- and polyfluoroalkyl substances (PFAS), antibiotic resistance genes (ARGs), pharmaceuticals and personal care products (PPCPs), and pesticides may lead to unintended environmental contamination through many pathways in multiple matrices. This statewide, multi-matrix study of contaminants of global concern (CGCs) in agricultural streams across Iowa (United States) is the first to examine multiple CGCs in water, bed sediment, and fish to understand their occurrence in small streams located in regions of intense agriculture activity. Iowa plays a pivotal role in agriculture, with more than 85% of Iowa’s landscape devoted to agriculture making it an ideal location for determining the prevalence of CGCs to provide critical baseline exposure data. Fifteen sites were sampled across a range of predominant land uses (e.g., poultry, swine); all sites had detections of microplastics in all matrices. Concentrations of PFAS varied but were detected in water and sediment; all fish had detections of perfluorooctanesulfonate (PFOS), a type of PFAS. More than 50% of water and bed sediment samples had detections of ARGs. The most frequently detected PPCP was metformin. No sites had a cumulative exposure activity ratio greater than 1.0 for chemical exposures; 13 sites were above the 0.001 precautionary threshold. Toxicity quotients calculated using Aquatic Life Benchmarks were below the 0.1 moderate risk threshold for chemical exposures for all but one site. For fish, all sites exceeded the moderate and high-risk thresholds proposed for microplastic particles for food dilution (both chronic and acute exposures) and all sites exceeded the microplastic moderate threshold proposed for chronic tissue translocation, and two sites exceeded the threshold for acute tissue translocation.

Iowa↗

USGS2020

The assessment and remediation of mercury contaminated sites: A review of current approaches

Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial extent of contamination, Hg stable isotope fractionation to identify sources and transformation processes, and solid-phase characterization (XAFS) to evaluate Hg forms. The understanding of Hg bioavailability for methylation has been improved by methods such as sequential chemical extractions and porewater measurements, including the use of diffuse gradient in thin-film (DGT) samplers. These approaches have shown varying success in identifying bioavailable Hg fractions and further study and field applications are needed. The downstream accumulation of methylmercury (MeHg) in biota is a concern at many contaminated sites. Identifying the variables limiting/controlling MeHg production—such as bioavailable inorganic Hg, organic carbon, and/or terminal electron acceptors (e.g. sulfate, iron) is critical. Mercury can be released from contaminated sites to the air and water, both of which are influenced by meteorological and hydrological conditions. Mercury mobilized from contaminated sites is predominantly bound to particles, highly correlated with total sediment solids (TSS), and elevated during stormflow. Remediation techniques to address Hg contamination can include the removal or containment of Hg contaminated materials, the application of amendments to reduce mobility and bioavailability, landscape/waterbody manipulations to reduce MeHg production, and food web manipulations through stocking or extirpation to reduce MeHg accumulated in desired species. These approaches often rely on knowledge of the Hg forms/speciation at the site, and utilize physical, chemical, thermal and biological methods to achieve remediation goals. Overall, the complexity of Hg cycling allows many different opportunities to reduce/mitigate impacts, which creates flexibility in determining suitable and logistically feasible remedies.

Science of the Total Environment↗

USGS2016

Trophic magnification of organic chemicals: A global synthesis

Production of organic chemicals (OCs) is increasing exponentially, and some OCs biomagnify through food webs to potentially toxic levels. Biomagnification under field conditions is best described by trophic magnification factors (TMFs; per trophic level change in log-concentration of a chemical) which have been measured for more than two decades. Syntheses of TMF behavior relative to chemical traits and ecosystem properties are lacking. We analyzed >1500 TMFs to identify OCs predisposed to biomagnify and to assess ecosystem vulnerability. The highest TMFs were for OCs that are slowly metabolized by animals (metabolic rate k M < 0.01 day –1 ) and are moderately hydrophobic (log K OW 6–8). TMFs were more variable in marine than freshwaters, unrelated to latitude, and highest in food webs containing endotherms. We modeled the probability that any OC would biomagnify as a combined function of K OW and k M . Probability is greatest (&sim;100%) for slowly metabolized compounds, regardless of K OW , and lowest for chemicals with rapid transformation rates ( k M > 0.2 day –1 ). This probabilistic model provides a new global tool for screening existing and new OCs for their biomagnification potential.

Environmental Science & Technology↗

USGS2016

Gene transcript profiling in sea otters post-Exxon Valdez oil spill: A tool for marine ecosystem health assessment

Using a panel of genes stimulated by oil exposure in a laboratory study, we evaluated gene transcription in blood leukocytes sampled from sea otters captured from 2006–2012 in western Prince William Sound (WPWS), Alaska, 17–23 years after the 1989 Exxon Valdez oil spill (EVOS). We compared WPWS sea otters to reference populations (not affected by the EVOS) from the Alaska Peninsula (2009), Katmai National Park and Preserve (2009), Clam Lagoon at Adak Island (2012), Kodiak Island (2005) and captive sea otters in aquaria. Statistically, sea otter gene transcript profiles separated into three distinct clusters: Cluster 1, Kodiak and WPWS 2006–2008 (higher relative transcription); Cluster 2, Clam Lagoon and WPWS 2010–2012 (lower relative transcription); and Cluster 3, Alaska Peninsula, Katmai and captive sea otters (intermediate relative transcription). The lower transcription of the aryl hydrocarbon receptor (AHR), an established biomarker for hydrocarbon exposure, in WPWS 2010–2012 compared to earlier samples from WPWS is consistent with declining hydrocarbon exposure, but the pattern of overall low levels of transcription seen in WPWS 2010–2012 could be related to other factors, such as food limitation, pathogens or injury, and may indicate an inability to mount effective responses to stressors. Decreased transcriptional response across the entire gene panel precludes the evaluation of whether or not individual sea otters show signs of exposure to lingering oil. However, related studies on sea otter demographics indicate that by 2012, the sea otter population in WPWS had recovered, which indicates diminishing oil exposure.

Alaska↗

USGS2022

Biology: Integrating core to essential variables (Bio-ICE) task team report for marine mammals

Marine mammals are wide-ranging, relatively long-lived organisms that play a crucial role in maintaining healthy ocean ecosystems. Often referred to as ecosystem engineers and sentinel species in marine ecosystems, these charismatic megafauna feed at a variety of trophic levels, affecting food web dynamics and cycling of chemicals and nutrients in the water column as well as in benthic habitats, both nearshore and in the deep ocean. An understanding of their abundance and distribution is an essential starting point for evaluating their role in ocean ecosystems. Accordingly, marine mammals have been included among key variables to monitor in ocean observing systems, from core variables for the U.S. Integrated Ocean Observing System (IOOS) to an Essential Ocean Variable (EOV) for the Global Ocean Observing System (GOOS). They also contribute to several Essential Biodiversity Variables (EBVs) for the Group on Earth Observations Biodiversity Observation Network (GEO BON). Further, evaluation of the health of marine mammal populations will help deliver societal benefits by contributing to the UN Decade of Ocean Science for Sustainable Development; informing reporting activities such as the World Ocean Assessment; and supporting achievement of Sustainable Development Goal 14, the post-2020 framework for the Convention for Biological Diversity, and a new treaty for conservation and sustainable use of marine biodiversity beyond national jurisdiction. In the U.S., the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (FWS) are required to produce stock assessments for marine mammals under the Marine Mammal Protection Act (MMPA, 16 U.S.C. §1371 et seq.). Stock assessment analyses require accurate, up to-date information on abundance and distribution to inform appropriate management and/or conservation measures. Despite the availability of information on abundance and distribution within the stock assessment reports, availability and accessibility of the underlying data to the broader ocean observing community and contribution to EOVs remain inconsistent.

Report↗

USGS2003

An introduction to the San Francisco Estuary tidal wetlands restoration series

Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter “Estuary”). Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period. However, many other changes have also occurred in the Estuary concurrent with the declines of native species. Other factors that might be important in species declines include the effects of construction of upstream dams, large and small water diversions within the Sacramento-San Joaquin Delta, agricultural pesticides, trace elements from industrial and agricultural activities, and invasions of alien species. Discussions among researchers, managers, and stakeholders have identified a number of uncertainties regarding the potential benefits of tidal wetland restoration. The articles of the Tidal Wetlands Restoration Series address four major issues of concern. Stated as questions, these are: 1. Will tidal wetland restoration enhance populations of native fishes? 2. Will wetland restoration increase rates of methylation of mercury? 3. Will primary production and other ecological processes in restored tidal wetlands result in net export of organic carbon to adjacent habitats, resulting in enhancement of the food web? Will the carbon produced contribute to the formation of disinfection byproducts when disinfected for use as drinking water? 4. Will restored tidal wetlands provide long-term ecosystem benefits that can be sustained in response to ongoing physical processes, including sedimentation and hydrodynamics? Reducing the uncertainty surrounding these issues is of critical importance because tidal wetland restoration is assumed to be a critical tool for enhancement of native species and ecosystem processes in the Estuary.

California↗

USGS2023

Gains and gaps in knowledge surrounding freshwater mollusk ecosystem services

Ecosystems provide essential services to people including food, water, climate regulation, and aesthetic experiences. Biodiversity can enhance and stabilize ecosystem function and the resulting services natural systems provide. Freshwater mollusks are a diverse group that provide a variety of ecosystem services through their feeding habits (e.g., filter feeding, grazing), top-down and bottom-up effects on food webs, provisioning of habitat, use as a food resource by people, and cultural importance. Research focused on quantifying the direct and indirect ways mollusks influence ecosystem services may help inform policy makers and the public about the value of mollusk communities to society. The Freshwater Mollusk Conservation Society highlighted the need to evaluate mollusk ecosystem services in their 2016 National Strategy for the Conservation of Native Freshwater Mollusks, and, while significant progress has been made, considerable work remains across the research, management, and outreach communities. We briefly review the global status of native freshwater mollusks, assess the current state of knowledge regarding their ecosystem services, and highlight recent advances and knowledge gaps to guide further research and conservation actions. Our intention is to provide ecologists, conservationists, economists, and social scientists with information to improve science-based consideration of the social, ecological, and economic value of mollusk communities to healthy aquatic systems.

Freshwater Mollusk Biology and Conservation↗

USGS2023

Mercury isotope values in shoreline spiders reveal transfer of aquatic mercury sources to terrestrial food webs

The transfer of aquatic contaminants, including mercury (Hg), to terrestrial food webs is an often-overlooked exposure pathway to terrestrial animals. While research has implemented the use of shoreline spiders to assess aquatic to terrestrial Hg transfer, it is unclear whether Hg sources, estimated from isotope ratios, can be successfully resolved to inform site assessments and remedy effectiveness. To examine aquatic to terrestrial Hg transfer, we collected shoreline spiders ( Tetragnatha spp.) and aquatic insect larvae (suborder Anisoptera) across a mosaic of aquatic and shoreline habitats in the St. Louis River and Bad River, tributaries to Lake Superior. The fraction of industrial Hg in sediments was reflected in the δ 202 Hg values of aquatic dragonfly larvae and predatory fish, connecting benthic Hg sources to the aquatic food web. Shoreline spiders mirrored these aquatic Hg source signatures with highly positive correlations in δ 202 Hg between tetragnathids and dragonfly larvae ( r 2 = 0.90). Further assessment of different spider taxa (i.e., araneids and pisaurids) revealed that differences in prey consumption and foraging strategies resulted in isotope differences, highlighting the importance of spider taxa selection for Hg monitoring efforts.

Minnesota, Wisconsin↗

USGS2018

Assessing wild juvenile trout ecology in the lower Mountain Fork

Reservoir tailwaters can be valuable fisheries for Rainbow Trout ( Oncorhynchus mykiss ), which is commonly stocked as mitigation for the altered habitat because it performs well as a put-and-take species in these thermally depressed systems. These fisheries are usually sustained by stocking due to flow fluctuations and lack of suitable spawning habitat that may limit natural reproduction. The Lower Mountain Fork River (LMFR) below Broken Bow Dam in southeastern Oklahoma is one of two year-round trout fisheries in the state and wild, juvenile Rainbow Trout were documented beginning in 2006, prompting speculation about the potential for a self-sustaining population. To determine this potential, we searched several sites over two years throughout the LMFR for wild, juvenile Rainbow Trout to estimate several parameters related to their population status (e.g., age, growth, time of spawning and hatching, and prey use). We also assessed the availability of macroinvertebrate prey to determine how food resources may affect trout sustainability. We found wild, juvenile Rainbow Trout each year, but only at sites within the first 4.5 km of the 19-km tailwater. Juvenile trout were the result of spawning that took place from late January through mid-April. Growth and body condition were variable between years, but similar to other systems. Weekly survival estimates using catch curves were low (<80%), suggesting limited potential for recruitment; however, declining catchability of larger juvenile fish likely biased these estimates. Wild, juvenile Rainbow Trout ate a variety of food items, but selected for Amphipoda and Diplostraca and against Trichoptera. Overlap in diet with adult Rainbow Trout was low (Bray-Curtis dissimilarity = 0.70). Macroinvertebrate prey resources available to trout varied among management zones, being most abundant in Zone 1 and Zone 3. Potential for a wild fishery may exist in the upper portion of the LMFR but additional research on recruitment to adulthood would be required to provide a more definitive answer.

Oklahoma↗

USGS2014

Demographics of piscivorous colonial waterbirds and management implications for ESA-listed salmonids on the Columbia Plateau

We investigated colony size, productivity, and limiting factors for five piscivorous waterbird species nesting at 18 locations on the Columbia Plateau (Washington) during 2004–2010 with emphasis on species with a history of salmonid ( Oncorhynchus spp.) depredation. Numbers of nesting Caspian terns ( Hydroprogne caspia ) and double-crested cormorants ( Phalacrocorax auritus ) were stable at about 700–1,000 breeding pairs at five colonies and about 1,200–1,500 breeding pairs at four colonies, respectively. Numbers of American white pelicans ( Pelecanus erythrorhynchos ) increased at Badger Island, the sole breeding colony for the species on the Columbia Plateau, from about 900 individuals in 2007 to over 2,000 individuals in 2010. Overall numbers of breeding California gulls ( Larus californicus ) and ring-billed gulls ( L. delawarensis ) declined during the study, mostly because of the abandonment of a large colony in the mid-Columbia River. Three gull colonies below the confluence of the Snake and Columbia rivers increased substantially, however. Factors that may limit colony size and productivity for piscivorous waterbirds nesting on the Columbia Plateau included availability of suitable nesting habitat, interspecific competition for nest sites, predation, gull kleptoparasitism, food availability, and human disturbance. Based on observed population trends alone, there is little reason to project increased impacts to juvenile salmonid survival from tern and cormorant populations. Additional monitoring and evaluation may be warranted to assess future impacts of the growing Badger Island American white pelican colony and those gull colonies located near mainstem dams or associated with Caspian tern colonies where kleptoparasitism is common.

Columbia Plateau↗