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At least 721 records · Page 40Linked to original sources

USGS2014

Water-chemistry data collected in and near Kaloko-Honokohau National Historical Park, Hawaii, 2012–2014

Kaloko-Honokōhau National Historical Park (KAHO) on western Hawaiʻi was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities, including the preservation of a variety of culturally and ecologically significant water resources that are vital to this mission. KAHO water bodies provide habitat for 1 threatened, 11 endangered, and 3 candidate threatened or endangered species. These habitats are sustained by, and in the case of ʻAimakapā Fishpond and the anchialine pools, entirely dependent on, groundwater from the Keauhou aquifer system. Development of inland impounded groundwater in the Keauhou aquifer system may affect the coastal freshwater-lens system on which KAHO depends, if the inland impounded-groundwater and coastal freshwater-lens systems are hydrologically connected. This report documents water-chemistry results from a U.S. Geological Survey study that collected and analyzed water samples from 2012 to 2014 from 25 sites in and near KAHO to investigate potential geochemical indicators in water that might indicate the presence or absence of a hydrologic connection between the inland impounded-groundwater and coastal freshwater-lens systems in the area. Samples were collected under high-tide and low-tide conditions for KAHO sites, and in dry-season and wet-season conditions for all sites. Samples were collected from two ocean sites, two fishponds, three anchialine pools, and three monitoring wells within KAHO. Two additional nearshore wells were sampled on property adjacent to and north of KAHO. Additional samples from the freshwater-lens system were collected from six inland wells located upslope from KAHO, including three production wells. Seven production wells in the inland impounded-groundwater system also were sampled. Water samples were analyzed for major ions, selected trace elements, rare-earth elements, strontium-isotope ratio, and stable isotopes of water. Precipitation samples from five sites were collected roughly along a transect upslope from KAHO. All precipitation samples were analyzed for stable isotopes of water and some precipitation samples were analyzed for rare-earth and selected trace elements.

Hawai'i↗

USGS2020

Cryptic lives of conspicuous animals: Otolith chemistry chronicles life histories of coastal lagoon fishes

Bar-built coastal lagoons are dynamic ecosystems at the land-sea interface that are important habitats for a variety of species. This study examined the habitat ecology of two lagoon species, the endangered Tidewater Goby ( Eucyclogobius newberryi ) and the Prickly Sculpin ( Cottus asper ) by reconstructing individual life histories from patterns in the concentration of the element Sr (as ratioed to Ca; Sr:Ca) in otoliths. Specific objectives were to (1) elucidate any movements of individual fishes among three primary habitat components of typical bar-built lagoon systems: coastal ocean, brackish lagoon, and freshwater watershed streams, and (2) determine if either species exhibited a consistent life history as defined by a stereotypical otolith Sr:Ca chronology, which could be indicative of a consistent range of salinity or temperature occupied through ontogeny. Results suggested that Tidewater Goby was a lagoon resident and that Prickly Sculpin exhibited migrations between lagoon and watershed stream habitats. There was no strong evidence in either species of ocean occupancy or of a stereotypical Sr:Ca chronology, the latter suggesting the full range of available lagoon habitat in terms of salinity and temperature was likely utilized at all life stages. These findings add to the body of evidence that bar-built lagoons are not isolated habitats, and holistic management of these habitats with adjoining watershed and marine environments could increase habitat connectivity across the landscape, with potential benefits to fishes.

California↗

USGS2025

Integrating sea level rise scenarios into Everglades restoration planning

One of the largest and most expensive restoration efforts in the world is occurring in the Everglades, a sub-tropical freshwater wetland system located in southern Florida. This unique ecosystem supports several endangered species, provides flood control for Florida’s large urban population, and provides water for both agriculture and drinking supply within the state. The Comprehensive Everglades Restoration Plan (CERP), authorized by Congress in 2000, guides federal, state, and local efforts to build the infrastructure necessary to bring more water into the Everglades and restore its ecological integrity, while balancing other water-related needs such as water supply and flood protection in the human environment. The Everglades encompasses the southern coast of Florida and restoration efforts are likely to be impacted by climate-induced sea level rise. However, currently, many project planning studies do not formally incorporate the potential impacts of sea level rise when evaluating restoration plan outcomes. Resource managers and project planners require methods and tools to confidently incorporate scenarios of sea level rise into their evaluations. The U.S. Geological Survey (USGS) and partners from the University of Florida worked with project planners from multiple agencies to identify restoration questions for consideration when addressing sea level rise. In addition, our project team sought to understand the types of sea level rise decision-support tools that would be of interest, and then worked with Everglades restoration managers and project planners to develop those tools. The tools developed by this project can be used by project planners to inform their decision-making abilities when considering multiple restoration plans across the Everglades landscape. Specifically, the novel ways to visualize output information from ecological models that came of this project can help project planners compare alternative restoration plans that include potential sea level rise impacts. This effort demonstrates how incorporating sea level rise scenarios into Everglades restoration project planning can help managers decide whether projects will maintain or improve ecological integrity and evaluate water availability for wildlife and humans.

Final Report↗

USGS2009

Estuarine Ecology of Juvenile Salmon in Western Alaska: a Review

In the late 1990s and early 2000s, large declines in numbers of chum salmon Oncorhynchus keta and Chinook salmon O. tshawytscha returning to the Arctic-YukonKuskokwim (AYK) region (Alaska, USA) illuminated the need for an improved understanding of the variables controlling salmon abundance at all life stages. In addressing questions about salmon abundance, large gaps in our knowledge of basic salmon life history and the critical early marine life stage were revealed. In this paper, results from studies conducted on the estuarine ecology of juvenile salmon in western Alaska are summarized and compared, emphasizing timing and distribution during outmigration, environmental conditions, age and growth, feeding, and energy content of salmon smolts. In western Alaska, water temperature dramatically changes with season, ranging from 0°C after ice melt in late spring/early summer to 19°C in July. Juvenile salmon were found in AYK estuaries from early May until August or September, but to date no information is available on their residence duration or survival probability. Chum salmon were the most abundant juvenile salmon reported, ranging in percent catch from <0.1% to 4.7% and most research effort has focused on this species. Abundances of Chinook salmon, sockeye salmon O. nerka, and pink salmon O. gorbuscha varied among estuaries, while coho salmon O. kisutch juveniles were consistently rare, never amounting to more than 0.8% of the catch. Dietary composition of juvenile salmon was highly variable and a shift was commonly reported from epibenthic and neustonic prey in lower salinity water to pelagic prey in higher salinity water. Gaps in the knowledge of AYK salmon estuarine ecology are still evident. For example, data on outmigration patterns and residence timing and duration, rearing conditions and their effect on diet, growth, and survival are often completely lacking or available only for few selected years and sites. Filling gaps in knowledge concerning salmon use and survival in estuarine and near-shore habitats within the AYK region will aid in assessing the relative roles of all habitats (freshwater to marine) in controlling salmon abundance.

Alaska↗

USGS2023

Appendix D: Synthesis element 1 (revised): Water temperature effects on fisheries and stream health in nontidal waters

A limited review of relevant scientific literature related to temperature sensitivities of fish species, stream health indicators, and any related geospatial information was conducted. Based on this review, we provide a syntheses of information related to nontidal waters in the Chesapeake Bay Rising stream temperatures will have a range of impacts on nontidal aquatic ecosystems. Cold headwaters and associated species like brook trout and sculpin are especially vulnerable to higher stream temperatures. Efforts could be taken to identify and protect high quality resilient cold headwater brook trout (Salvelinus fontinalis) habitat. More information on groundwater impacts on stream temperatures and ecologically relevant temperature thresholds for species of concern could help resource managers identify temperature resilient habitats and populations. A vulnerability assessment could be valuable to better understand the drivers and stressors of rising stream temperatures, their effects on aquatic resources, and the risk to fish and other aquatic species. Further research could help in developing and fully vetting a complete list of cold/cool water benthic macroinvertebrate taxa and freshwater mussel taxa that are vulnerable to temperature change in the Chesapeake watershed.

Report↗

USGS2023

A global ecological signal of extinction risk in marine ray-finned fishes (class Actinopterygii)

Many marine fish species are experiencing population declines, but their extinction risk profiles are largely understudied in comparison to their terrestrial vertebrate counterparts. Selective extinction of marine fish species may result in rapid alteration of the structure and function of ocean ecosystems. In this study, we compiled an ecological trait dataset for 8,185 species of marine ray-finned fishes (class Actinopterygii) from FishBase and used phylogenetic generalized linear models to examine which ecological traits are associated with increased extinction risk, based on the International Union for the Conservation of Nature Red List. We also assessed which threat types may be driving these species toward greater extinction risk and whether threatened species face a greater average number of threat types than non-threatened species. We found that larger body size and/or fishes with life histories involving movement between marine, brackish, and freshwater environments are associated with elevated extinction risk. Commercial harvesting threatens the greatest number of species, followed by pollution, development, and then climate change. We also found that threatened species, on average, face a significantly greater number of threat types than non-threatened species. These results can be used by resource managers to help address the heightened extinction risk patterns we found.

Cambridge Prisms: Extinction↗

USGS2022

Urbanization and stream ecology: Moving the bar on multidisciplinary solutions to wicked urban stream problems

Decades of research on the effects of urbanization on stream ecology have shown that urban stream problems are inherently wicked. These problems are wicked in the sense that they are difficult to solve because information is incomplete, changing, or conflicting and because finding potential solutions often requires input from stakeholders who can have conflicting and competing values. The 5 th Symposium on Urbanization and Stream Ecology (SUSE5) in February 2020 brought together diverse perspectives from scientists, managers, practitioners, and local communities. Participants at SUSE5 discussed the state of the science in urban stream ecology and worked through in-depth case studies in teams to tackle complex real-world problems in urban stream management. The papers in this special series on urbanization and stream ecology include empirical research studies and synthesis papers sparked by discussions at SUSE5 and advance multidisciplinary solutions to wicked urban stream problems.

Freshwater Science↗

USGS2022

Modeling functional flows in California rivers

Environmental flows are critical to the recovery and conservation of freshwater ecosystems worldwide. However, estimating desired ranges of environmental flows across large, diverse landscapes is challenging. To advance protections of environmental flows for streams in California, USA, we developed a statewide modeling approach focused on functional components of the natural flow regime. Functional flow components in California streams—fall pulse flows, wet season peak flows and base flows, the spring flow recession, and dry season baseflows—support essential physical and ecological processes in riverine ecosystems. These functional flow components can be represented by functional flow metrics (FFMs) and quantified by their magnitude, timing, frequency, duration, and rate-of-change from daily streamflow records. After quantifying FFMs at reference-quality streamflow gages in California, we used machine-learning methods to estimate their natural range of values for all stream reaches in the state based on physical watershed characteristics and climatic factors. We found that the models performed well in predicting FFMs in streams across a diversity of landscape and climate contexts, according to several model performance criteria. Using the predicted FFM values, we established initial estimates of ecological flows that are expected to support critical functions and are broadly protective of ecosystem health. Modeling functional flows statewide offers a pathway for increasing the pace and scale of environmental flow protections in California and beyond.

California↗

USGS2020

Seasonal habitat use indicates that depth may mediate the potential for invasive round goby impacts in inland lakes

The round goby ( Neogobius melanostomus ) is among the fastest-spreading introduced aquatic species in North America and is radiating inland from the Great Lakes into freshwater ecosystems across the landscape. Predicting and managing the impacts of round gobies requires information on the factors influencing their distribution in habitats along the invasion front, yet this information is not available for many recently invaded ecosystems. We evaluated the seasonal habitat use and biomass of round gobies in an inland temperate lake to define the spatiotemporal scope of biological interactions at the leading edge of the round goby invasion. Using novel statistical approaches, we combined hierarchical models that control for imperfect species detection with flexible smooth terms to describe non-linear relationships between round goby abundance and environmental gradients. Subsequently, we generated accurate detection-corrected estimates of the standing stock biomass of round gobies. Our results show seasonally differentiated habitat niches, where suitable round goby habitat in summer months is restricted to shallow depths (<18.4 m) with a mixture of vegetative and mussel cover. We found high round goby biomass of 122 kg/ha in occupied habitats during the summer, with a total lake-wide biomass of 766,000 kg. In winter, round gobies migrate to deep offshore habitats and disperse, dramatically altering their scope for biological interactions with resident aquatic species across summer and winter seasons. The results of this study indicate that the scope of biological interactions in inland lakes may be seasonally variable, with potential for high round goby biomass in shallow lakes or at the periphery of deep lakes in the summer months. Such shallow-water habitats may therefore present higher risk of ecological impacts from round gobies in invaded lentic ecosystems. As round gobies expand inland, consideration of seasonal habitat use will be an important factor in predicting the impacts of this pervasive invader.

New York↗

USGS2025

Sampling mass mortality events to enable diagnoses: A protocol using freshwater mussels

Many taxa around the globe are threatened by often unexplained mass mortality events (MMEs), which can decimate populations and compromise key ecosystem functions. One example of a highly threatened taxon facing frequent MMEs is freshwater mussels (Unionida). There has been a recent increase in interest in understanding the causes of freshwater mussel MMEs, but standardised methodologies for how best to respond to them to facilitate diagnoses are unavailable. When an MME is observed, swift and appropriate sample collection is imperative owing to the transient nature of these phenomena. Here we provide structured guidance that will facilitate rapid and appropriate sampling of MMEs, using freshwater mussels as an example. We set out standardised procedures for sample collection, preparation and preservation. The procedures we outline will improve our capacity for diagnostic investigations of MMEs and other mortality events, not only in freshwater mussels but also across many other taxa. This, in turn, can inform appropriate management responses.

Methods in Ecology and Evolution↗

USGS2013

Descriptors of natural thermal regimes in streams and their responsiveness to change in the Pacific Northwest of North America

1. Temperature is a major driver of ecological processes in stream ecosystems, yet the dynamics of thermal regimes remain poorly described. Most work has focused on relatively simple descriptors that fail to capture the full range of conditions that characterise thermal regimes of streams across seasons or throughout the year. 2. To more completely describe thermal regimes, we developed several descriptors of magnitude, variability, frequency, duration and timing of thermal events throughout a year. We evaluated how these descriptors change over time using long-term (1979–2009), continuous temperature data from five relatively undisturbed cold-water streams in western Oregon, U.S.A. In addition to trends for each descriptor, we evaluated similarities among them, as well as patterns of spatial coherence, and temporal synchrony. 3. Using different groups of descriptors, we were able to more fully capture distinct aspects of the full range of variability in thermal regimes across space and time. A subset of descriptors showed both higher coherence and synchrony and, thus, an appropriate level of responsiveness to examine evidence of regional climatic influences on thermal regimes. Most notably, daily minimum values during winter–spring were the most responsive descriptors to potential climatic influences. 4. Overall, thermal regimes in streams we studied showed high frequency and low variability of cold temperatures during the cold-water period in winter and spring, and high frequency and high variability of warm temperatures during the warm-water period in summer and autumn. The cold and warm periods differed in the distribution of events with a higher frequency and longer duration of warm events in summer than cold events in winter. The cold period exhibited lower variability in the duration of events, but showed more variability in timing. 5. In conclusion, our results highlight the importance of a year-round perspective in identifying the most responsive characteristics or descriptors of thermal regimes in streams. The descriptors we provide herein can be applied across hydro-ecological regions to evaluate spatial and temporal patterns in thermal regimes. Evaluation of coherence and synchrony of different components of thermal regimes can facilitate identification of impacts of regional climate variability or local human or natural influences.

Freshwater Biology↗

USGS2002

Modeling fish community dynamics in Florida Everglades: Role of temperature variation

Temperature variation is an important factor in Everglade wetlands ecology. A temperature fluctuation from 17°C to 32°C recorded in the Everglades may have significant impact on fish dynamics. The short life cycles of some of Everglade fishes has rendered this temperature variation to have even more impacts on the ecosystem. Fish population dynamic models, which do not explicitly consider seasonal oscillations in temperature, may fail to describe the details of such a population. Hence, a model for fish in freshwater marshes of the Florida Everglades that explicitly incorporates seasonal temperature variations is developed. The model's main objective is to assess the temporal pattern of fish population and densities through time subject to temperature variations. Fish population is divided into 2 functional groups (FGs) consisting of small fishes; each group is subdivided into 5-day age classes during their life cycles. Many governing sub-modules are set directly or indirectly to be temperature dependent. Growth, fecundity, prey availability, consumption rates and mortality are examples. Several mortality sub-modules are introduced in the model, of which starvation mortality is set to be proportional to the ratio of prey needed to prey available at that particular time step. As part of the calibration process, the model is run for 50 years to ensure that fish densities do not go to extinction, while the simulation period is about 8 years. The model shows that the temperature dependent starvation mortality is an important factor that influences fish population densities. It also shows high fish population densities at some temperature ranges when this consumption need is minimum. Several sensitivity analyses involving variations in temperature terms, food resources and water levels are conducted to ascertain the relative importance of temperature dependence terms.

Water Science and Technology↗

USGS2019

Wasting disease and static environmental variables drive sea star assemblages in the northern Gulf of Alaska

Sea stars are ecologically important in rocky intertidal habitats where they can play an apex predator role, completely restructuring communities. The recent sea star die-off throughout the eastern Pacific, known as Sea Star Wasting Disease, has prompted a need to understand spatial and temporal patterns of sea star assemblages and the environmental variables that structure these assemblages. We examined spatial and temporal patterns in sea star assemblages (composition and density) across regions in the northern Gulf of Alaska and assessed the role of seven static environmental variables (distance to freshwater inputs, tidewater glacial presence, exposure to wave action, fetch, beach slope, substrate composition, and tidal range) in influencing sea star assemblage structure before and after sea star declines. Environmental variables correlated with sea star distribution can serve as proxies to environmental stressors, such as desiccation, attachment, and wave action. Intertidal sea star surveys were conducted annually from 2005 to 2018 at five sites in each of four regions that were between 100 and 420 km apart across the northern Gulf of Alaska. In the pre-disease years, assemblages were different among regions, correlated mostly to tidewater glacier presence, fetch, and tidal range. The assemblages after wasting disease were different from those before the event with lower diversity and lower density. In addition to these declines, the disease manifested itself at different times across the northern Gulf of Alaska and did not impact all species uniformly across sites. Post sea star wasting, there was a shift in the environmental variables that correlated with sea star structure, resulting in sea star assemblages being highly correlated with slope, fetch, and tidal range. In essence, sea star wasting disease resulted in a shift in the sea star assemblage that is now correlating with a slightly different combination of environmental variables. Understanding the delicate interplay of environmental variables that influence sea star assemblages could expand knowledge of the habitat preferences and tolerance ranges of important and relatively unstudied species within the northern Gulf of Alaska.

Alaska↗

USGS2009

Evaluation of a gastric radio tag insertion technique for anadromous river herring

Anadromous river herring (alewives Alosa pseudoharengus and blueback herring A. aestivalis ), which constitute a historically and ecologically important component of coastal rivers, have declined precipitously throughout the Atlantic seaboard. Suggested causes of river herring decline include commercial fishing and predation by striped bass Morone saxatilis . Although the causes of this recent trend are poorly understood, river herring are especially vulnerable to adverse impacts during their spring spawning migration. Radiotelemetry is an especially useful method for addressing potential problems encountered during the movement of these fish from the ocean to freshwater. In spite of frequent calls for evaluation of telemetry methods, controlled tests of posttagging effects are rare for alosids and virtually nonexistent for anadromous river herring. We developed a protocol for gastric tagging of anadromous river herring, and we used hatchery and field studies to evaluate behavior, tag placement, stress response, and posttagging mortality. We also compared tagger effects and quantified posttagging upstream movements of fish in the field. In controlled hatchery trials, no fish died at 10 min, 1 h, or 14 d posttagging. No tags were rejected, and only 1 of 35 tags ruptured the gut. In field cages, mortality, plasma cortisol, glucose, and chloride measured at 24 h were similar between tagged and untagged fish. In the field, 12 of 14 fish moved upriver after tagging and spent 114 h on average at upriver sites. Using a variety of approaches, we found no evidence that our tagging protocol adversely affected river herring in comparison with untagged fish that were subjected only to handling and holding. Our protocol, evaluated by comparing responses of tagged and untagged fish under controlled conditions, may be useful in future studies that seek to understand causes of decline for anadromous river herring.

Massachuetts↗

USGS2025

Status of water-quality conditions in the United States, 2010–20

Degradation of water quality can make water harmful or unusable for humans and ecosystems. Although many studies have assessed the effect of individual constituents or narrow suites of constituents on freshwater systems, no consistent, comprehensive assessment exists over the wide range of water-quality effects on water availability. Using published studies, data, and models completed at regional or national scales in the United States during 2010–20, this chapter moves towards a comprehensive assessment by summarizing how selected anthropogenic and geogenic water-quality constituents affect national-scale water availability for human and ecosystem needs. Several types of human health, agricultural, ecological, and beneficial-use standards or thresholds were used to provide context for categorizing surface-water and groundwater quality. Water availability for human and ecological use is limited by elevated concentrations of geogenic and anthropogenic constituents in surface and groundwater. Elevated concentrations of five geogenic constituents (arsenic, manganese, strontium, radium, and adjusted gross alpha) are common in groundwater and collectively affect the drinking water supply to over 30 million people. Surface water sourced drinking water supplies are impaired in about a third of assessed stream miles, most commonly because of non-mercury metals and salinity. Health-based violations at community water systems may disproportionately affect socially vulnerable communities. Ecological water uses are predominantly limited by nutrients, sediment, temperature, pathogens, salinity, and pesticides. Water availability for human and ecological use is adversely affected by human activities including human contaminant sources (for example, wastewater, agriculture), processes (for example, dredging, groundwater pumping), or permanent landscape modifications (for example, dams, urbanization). Primary contaminant sources vary spatially and include fertilizer and manure, atmospheric deposition, wastewater treatment plants, urban land, and a range of natural sources. Contaminants of emerging concern, contaminants without regulatory thresholds, and mixtures of geogenic and anthropogenic water contaminants also contribute to ecological degradation and human exposure.

conterminous United States↗

USGS2014

Gear and seasonal bias associated with abundance and size structure estimates for lentic freshwater fishes

All freshwater fish sampling methods are biased toward particular species, sizes, and sexes and are further influenced by season, habitat, and fish behavior changes over time. However, little is known about gear-specific biases for many common fish species because few multiple-gear comparison studies exist that have incorporated seasonal dynamics. We sampled six lakes and impoundments representing a diversity of trophic and physical conditions in Iowa, USA, using multiple gear types (i.e., standard modified fyke net, mini-modified fyke net, sinking experimental gill net, bag seine, benthic trawl, boat-mounted electrofisher used diurnally and nocturnally) to determine the influence of sampling methodology and season on fisheries assessments. Specifically, we describe the influence of season on catch per unit effort, proportional size distribution, and the number of samples required to obtain 125 stock-length individuals for 12 species of recreational and ecological importance. Mean catch per unit effort generally peaked in the spring and fall as a result of increased sampling effectiveness in shallow areas and seasonal changes in habitat use (e.g., movement offshore during summer). Mean proportional size distribution decreased from spring to fall for white bass Morone chrysops , largemouth bass Micropterus salmoides , bluegill Lepomis macrochirus , and black crappie Pomoxis nigromaculatus , suggesting selectivity for large and presumably sexually mature individuals in the spring and summer. Overall, the mean number of samples required to sample 125 stock-length individuals was minimized in the fall with sinking experimental gill nets, a boat-mounted electrofisher used at night, and standard modified nets for 11 of the 12 species evaluated. Our results provide fisheries scientists with relative comparisons between several recommended standard sampling methods and illustrate the effects of seasonal variation on estimates of population indices that will be critical to the future development of standardized sampling methods for freshwater fish in lentic ecosystems.

Iowa↗

USGS2021

Foraging in marine habitats increases mercury concentrations in a generalist seabird

Methylmercury concentrations vary widely across geographic space and among habitat types, with marine and aquatic-feeding organisms typically exhibiting higher mercury concentrations than terrestrial-feeding organisms. However, there are few model organisms to directly compare mercury concentrations as a result of foraging in marine, estuarine, or terrestrial food webs. The ecological impacts of differential foraging may be especially important for generalist species that exhibit high plasticity in foraging habitats, locations, or diet. Here, we investigate whether foraging habitat, sex, or fidelity to a foraging area impact blood mercury concentrations in western gulls ( Larus occidentalis ) from three colonies on the US west coast. Cluster analyses showed that nearly 70% of western gulls foraged primarily in ocean or coastal habitats, whereas the remaining gulls foraged in terrestrial and freshwater habitats. Gulls that foraged in ocean or coastal habitats for half or more of their foraging locations had 55% higher mercury concentrations than gulls that forage in freshwater and terrestrial habitats. Ocean-foraging gulls also had lower fidelity to a specific foraging area than freshwater and terrestrial-foraging gulls, but fidelity and sex were unrelated to gull blood mercury concentrations in all models. These findings support existing research that has described elevated mercury levels in species using aquatic habitats. Our analyses also demonstrate that gulls can be used to detect differences in contaminant exposure over broad geographic scales and across coarse habitat types, a factor that may influence gull health and persistence of other populations that forage across the land-sea gradient.

California, Oregon↗

USGS2018

Evaluating and managing environmental water regimes in a water-scarce and uncertain future

While the number of environmental flows and water science programmes continues to grow across the globe, there remains a critical need to better balance water availability in support of human and ecological needs and to recognise the environment as a legitimate user of water. In water‐stressed areas, this recognition has resulted in friction between water users in the public and private sectors. An opportunity exists for practitioners to be on the forefront of the science determining best practices for supporting environmental water regimes. This Special Issue brings together a collection of environmental flows science and water management papers organised around three major themes: (1) method development and testing; (2) application case studies; and (3) efficacy evaluation. Contents of this Special Issue are intended to foster collaboration and broaden transferability of the information, technical tools, models and methods needed to support environmental water management programmes. The technical sophistication of methods and modelling tools, while important to the advancement of environmental water science, may come at the expense of easily interpretable outcomes that positively influence management decisions. Researchers need to be more proactive in translating the results of advanced modelling methodologies into user‐friendly tools and methods. This will allow stakeholders and water managers to proactively test alternative water allocation scenarios to help address growing human water demands in the face of droughts and changes in climatic patterns. The application of environmental flows science and water management strategies cannot be done in isolation. Implementation involves a complex decision‐making process that integrates ecological, hydrologic and social science across diverse multifaceted governance systems and requires active stakeholder involvement. Scientists and managers must strengthen partnerships at multiple scales to develop sensible science investment strategies so that collective knowledge can be translated into wise environmental water management decisions.

Freshwater Biology↗