Search

Efficient management of invasive species benefits from understanding patterns of persistence and change over time. In this study, we compare distribution and abundance of the invasive macrophyte parrotfeather (Myriophyllum aquaticum) in an unregulated river system between the time near its presumed introduction and 20 years later. Initial surveys were conducted in 1996–1997, and were repeated in 2015–2016 using similar methodology. Moderate increases in the proportion of river kilometers with parrotfeather between the two periods were observed, but the distribution of sites with low, medium, and high abundance remained consistent, with small numbers of sites in either period having well-established extents of parrotfeather. The distributional extent has moved downstream, with the most upstream and downstream presences shifted by 17 and 28 river kilometers, respectively; however, parrotfeather remains sparse in the lower reaches below the historical downstream extent. Sites with high abundance and stable presence over time are in the intermediate segment of the river, indicating longitudinal and hydrologic controls on distribution. In contemporary sites, area of parrotfeather cover was associated with larger, deeper habitats, whereas dominance of parrotfeather occurred in smaller sites having uniformly shallow depth and low bank slopes. Sites where both abundance and dominance were low had dense canopy cover. Our results demonstrate that landscape and site-level characteristics restrict establishment and persistence of parrotfeather, and that hydrologic alterations to stabilize flow regimes and land use changes should be considered for their potential to increase presence of parrotfeather and other invasive aquatic plants in dynamic floodplain habitats.

We examined historical and contemporary trends for a suite of groundfish species in Puget Sound, Washington, USA, to ask how the groundfish community has responded following shifts in fishing regulations, climate, food web, and a growing human population in the surrounding watershed. We used contemporary data (1990-2017) from a standardized annual bottom trawl survey with historical logbook information (1948-1977) from a research vessel. We standardized data to account for spatial and temporal effects on catch rate by first fitting a Bayesian model to the contemporary data, and then using the posterior distributions of the covariates as prior distributions when fitting models to the historical data. We found that most of the 15 species chosen for analysis had highly variable population dynamics within both time periods, and that patterns of variability were similar in the contemporary and historical time period. Surprisingly, there was little evidence of community-wide recovery following regulations that first limited and then banned commercial bottom trawling in the late 1980s to mid-1990s. Spotted ratfish and English sole dominated catches in both time periods, and species that were common in the historical time period were also common in the contemporary time period. The absence of coherent community changes in response to fisheries regulations and other major social and ecological changes may signal the complex dynamics of an urban estuary that is subject to multiple external drivers, and speaks to the need to consider long-term dynamic behavior of populations and communities when establishing ecological indicators.

Environmental DNA (eDNA) analysis offers a promising tool for rapid and early detection of aquatic plant invasive species, but currently suffers from substantial unknowns that limit its wid...

Brazilian elodea (Egeria densa) is an invasive freshwater plant that demonstrates widespread ecological impacts in freshwater ecosystems and causes substantial economic damage. Here, we developed an environmental DNA assay for detection of E. densa to provide resource managers with a tool for early detection, identification, and monitoring of invasive populations.

Large floodplain rivers (LFRs) are currently threatened by high levels of human alteration, and utilization is expected to grow. Assessments to determine ecological condition should address the specific environmental features of these unique ecosystems, while conservation management requires balancing maintenance of good ecological condition with the ecosystem services provided by LFRs. However, a systematic evaluation of the scientific literature on assessment of ecological condition of LFRs and trade-offs to guide conservation management is currently lacking. Here, we reviewed 153 peer reviewed scientific articles to characterize methodological patterns and trends and identify knowledge gaps in the assessment of LFRs. Our review revealed that most approaches used classical biotic indices for assessing ecological condition of LFRs. However, the number of articles specifically addressing the peculiarities of LFRs was low. Many studies used watershed level surveys and assessed samples from small streams to large rivers using the same methodological protocol. Most studies evaluated the status of main stem river habitats only, indicating large knowledge gaps with respect to the diversity of river-floodplain habitat types or lateral connectivity. Studies related to management were oriented toward specific rehabilitation actions rather than broader conservation of LFRs. Papers relating to ecosystem services of LFRs were especially few. Most importantly, these studies did not distinguish the different functional units of river-floodplain habitat types (e.g. eupotamon, parapotamon) and their role in ecosystem services provision. Overall, the number of articles was too low for meaningful analyses of the relationships and tradeoffs between biodiversity conservation, maintaining ecological condition, and use of ecosystem services in LFRs. Our review highlights research gaps and emphasizes the importance of developing more holistic indicators of ecosystem condition, which better reflect landscape level changes in structure and functioning of LFRs. As human use of water and land increases, the need to develop more effective spatial conservation prioritization tools becomes more important. Empirical research in this field can aid in solving conflicts between socio-economic demands for ecosystem services and nature conservation of LFRs.

One of the most influential environmental laws in the US – the 1972 Clean Water Act – included the visionary objective of maintaining and restoring aquatic ecological integrity. However, the efficacy of the Act depends on how integrity is assessed. Reviewing the assessment literature for fresh waters over the past 40 years, we found evidence of methodological trends toward increased repeatability, transferability, and robustness of assessments over time. However, implementation gaps were revealed, based on the relatively weak linkages to freshwater policies, stakeholder involvement, emerging threats, and conservation opportunities. A related survey of assessment practitioners underscored the disparity between need versus availability of assessments that guide management policies. Technological changes in data collection and synthesis have clearly influenced assessments, and appear to have led to a reduced reliance on ecological response indicators and corresponding increases in stressor-based metrics. We recommend designing assessments around specific freshwater policies and regulations to improve applicability of assessment products for management and conservation.

Summary Natural resource agencies are increasingly required to prioritise management of multiple non-native aquatic plants (macrophytes) in freshwater ecosystems. Characterising the consequences of invasions for ecological processes and corresponding ecosystem services is fundamental to this decision-making process, but requires an understanding of impacts across physical, chemical, and biological responses. Accordingly, we evaluated the multi-trophic impacts of the invasive macrophyte Myriophyllum aquaticum (Haloragaceae; parrotfeather) along the mainstem Chehalis River, Washington, U.S.A. We examined invertebrate, plant and fish community responses to varying degrees of parrotfeather abundance and simultaneously characterised variation in physical structure and dissolved oxygen (DO) across the dominant native and non-native plant species. DO concentrations were significantly reduced and approached hypoxic levels in areas dominated by parrotfeather compared with native vegetation. Increased structural complexity, volume and biomass of parrotfeather was associated with increased diversity of epiphytic invertebrates. However, these more diverse invertebrate assemblages were dominated by amphipods, whereas native macrophytes were characterised by cladocerans, chironomids and gastropods. Non-native fishes (primarily centrarchid species) were more strongly associated with sites where parrotfeather was present and diversity of non-native fishes was positively correlated along a gradient of parrotfeather abundance. Native fish associated with parrotfeather areas were those that tend to be tolerant of degraded or lower quality habitats. We saw little evidence of exclusion of other macrophytes; native and non-native plant diversity and abundance were positively correlated with the parrotfeather gradient. This may reflect that analysis was done at a site level, and competitive dominance might be apparent by changes in species richness at smaller (plot) scales or over longer periods. Alternatively, parrotfeather may demonstrate minimal effects on native plant composition. Given the effects observed across multiple habitat characteristics and biota, parrotfeather appears to be a highly impactful invader where it establishes. Many of the changes we observed appear to derive from the emergent leaves and dense mat formation of parrotfeather compared with a submersed structure more typical of the native community. Our results suggest that managers should specifically consider contrasting characteristics between non-native and native physical structure when assessing and prioritising threats of invasive macrophytes.

The Olympic Mudminnow Novumbra hubbsi is a highly endemic freshwater fish found only in Washington State, where their distribution is limited to low-elevation wetland habitats. The distributional extent of the Olympic Mudminnow is well established, but local and watershed environmental features associated with their presence or absence within the range are poorly understood, making it difficult to determine habitat needs versus availability. We surveyed 22 sites in 2 years along the Chehalis River with the objective of modeling environmental characteristics associated with occupancy by Olympic Mudminnows, while also accounting for incomplete detection. Occupancy and detection probabilities were highly similar between years, and occupancy that incorporated detection probabilities was 47% higher than naive estimates in a given year. Modeling with environmental covariates supported the importance of low temperatures for predicting the occurrence of Olympic Mudminnows at sites, and detection within sites was associated most strongly with shallow depths and low dissolved oxygen. These results are consistent with prior research indicating the preferential use of groundwater springs by Olympic Mudminnows, particularly in warmer summer months. Our research expands the existing knowledge of Olympic Mudminnow distributions by documenting main-stem-oriented populations at varying levels of abundance and suggesting habitat features that may increase occupancy and detection probabilities. The sampling and modeling approach we describe also informs development of standardized survey protocols for Olympic Mudminnows, helping to optimize resources for monitoring occupancy and abundance across their limited range.

Coastal ecosystems face a variety of natural and anthropogenic influences, raising questions about mechanisms by which species abundance and composition change over time. We examined these questions by synthesizing 6 surface-trawling efforts in greater Puget Sound, Washington (USA), spanning 40 yr, and then determining changes in forage fish abundance and composition and jellyfish prevalence. We also assessed whether patterns were associated with potential anthropogenic pressures (human population density and commercial harvest) as well as large-scale climate signals. We found evidence for trends in abundance of all forage species in 4 sub-basins of Puget Sound. Cumulative distribution functions of catch per unit effort indicate that the historically dominant forage fishes (Pacific herring and surf smelt) have declined in sur- face waters in 2 sub-basins (Central and South Puget Sound) by up to 2 orders of magnitude. How- ever, 2 other species (Pacific sand lance and three-spine stickleback) increased in all 4 sub-basins. Consequently, species composition diverged among sub-basins over the last 40 yr. In addition, jelly - fish-dominated catches increased 3- to 9-fold in Central and South Puget Sound, and abundance positively tracked human population density across all basins. The strongest predictors of forage fish declines were human population density and commercial harvest. Climate signals offered additional explanatory power for forage fish but not jellyfish catch. These patterns suggest possi- ble linkages between coastal anthropogenic activities (e.g. development, pollution) and the abun- dance of forage fish and jellyfish in pelagic waters. Our findings also provide a basis for improving indicators for assessment, monitoring, and spatial planning to rehabilitate pelagic ecosystems.

We review and summarize the ecology and conservation status of the group of fishes commonly known as “mudminnows” (formerly known as the family Umbridae but recently reclassified as Esocidae), consisting of only five species distributed on three continents. These small-bodied fish—residing in freshwater habitats and exhibiting limited mobility—often occur in isolated populations across landscapes and are subject to conservation threats common to highly endemic species in close contact with anthropogenic impacts, such as pollution, habitat alteration, and nonnative species introductions. Herein we summarize current knowledge of the distributions, phylogenetic relationships, ecology, and conservation status of each species of mudminnow, including nonnative occurrence and distribution. We also outline the primary conservation threats to particular species and make recommendations for future research to promote much needed knowledge and conservation attention.

Development of skills in science communication is a well-acknowledged gap in graduate training, but the constraints that accompany research (limited time, resources, and knowledge of opportunities) make it challenging to acquire these proficiencies. Furthermore, advisors and institutions may find it difficult to support graduate students adequately in these efforts. The result is fewer career and societal benefits because students have not learned to communicate research effectively beyond their scientific peers. To help overcome these hurdles, we developed a practical approach to incorporating broad science communication into any graduate-school time line. The approach consists of a portfolio approach that organizes outreach activities along a time line of planned graduate studies. To help design the portfolio, we mapped available science communication tools according to 5 core skills essential to most scientific careers: writing, public speaking, leadership, project management, and teaching. This helps graduate students consider the diversity of communication tools based on their desired skills, time constraints, barriers to entry, target audiences, and personal and societal communication goals. By designing a portfolio with an advisor's input, guidance, and approval, graduate students can gauge how much outreach is appropriate given their other commitments to teaching, research, and classes. The student benefits from the advisors' experience and mentorship, promotes the group's research, and establishes a track record of engagement. When graduate student participation in science communication is discussed, it is often recommended that institutions offer or require more training in communication, project management, and leadership. We suggest that graduate students can also adopt a do-it-yourself approach that includes determining students' own outreach objectives and time constraints and communicating these with their advisor. By doing so we hope students will help create a new culture of science communication in graduate student education.

Rapid environmental change in freshwater ecosystems has created a need to understand the interactive effects of multiple stressors, with temperature and invasive predators identified as key threats to imperiled fish species. We tested the separate and interactive effects of water temperature and predation by non-native smallmouth bass (Micropterus dolomieu) on the lethal (mortality) and sublethal (behavior, physiology, and growth) effects for juvenile Chinook salmon (Oncorhynchus tshawytscha) in seminatural stream channel experiments. Over 48 h trials, there was no difference in direct predation with warmer temperatures, but significant interactive effects on sublethal responses of juvenile salmon. Warmer temperatures resulted in significantly stronger and more variable antipredator responses (surface shoaling and swimming activity), while physiological indicators (plasma glucose, plasma cortisol) suggested suppression of physiological mechanisms in response to the combined stressors. These patterns corresponded with additive negative growth in predation, temperature, and combined treatments. Our results suggest that chronic increases in temperature may not increase direct predation over short periods, but can result in significant sublethal costs with negative implications for long-term development, disease resistance, and subsequent size-selective mortality of Pacific salmon. Resume : Des changements environnementaux rapides affectant les ecosystemes d'eau douce decoule la necessite de comprendre les effets interactifs de stresseurs multiples, la temperature et les predateurs envahissants constituant les principales menaces identifiees pour les especes de poissons en peril. Nous avons teste les effets isoles et interactifs de la

SUMMARY 1. Non-native predators might inflict proportionally higher mortality on prey that have no previous experience of them, compared to species that have coexisted with the predator for some time. 2. We tested whether juvenile Chinook salmon (Oncorhynchus tshawytscha) were less able to recognise a non-native than a native predator, by investigating behavioural responses to the chemical cues of the invasive smallmouth bass (Micropterus dolomieu) and the native northern pikeminnow (Ptychocheilus oregonensis) in both laboratory and field experiments. 3. Laboratory results demonstrated strong innate antipredator responses of individual juvenile Chinook salmon to northern pikeminnow; fish spent 70% of time motionless and exhibited 100% greater panic response than in controls. By contrast, antipredator responses to the chemical cues of smallmouth bass did not differ from controls. 4. These results were supported by similar differences in recognition of these predator odours by groups of juvenile Chinook salmon in fully natural conditions, though responses reflected a greater range of antipredator behaviours by individuals. In field trials, responses to northern pikeminnow odour resulted in increased flight or absence, reductions in swimming and foraging, and increased time spent near the substratum, compared to smallmouth bass odour. 5. Given that survival of juvenile fish is facilitated by predator recognition, our results support the hypothesis that naivety may be an important factor determining the effect of non-native predators on prey populations. Efforts to manage the effect of native and non-native predators may benefit by considering complex behavioural interactions, such as these at the individual and group levels.

Washington State's only endemic fish, Olympic mudminnow (Novumbra hubbsi), was listed as state “Sensitive” in 1999 due to a small range and concern about population declines and threats, including impacts from nonnative competitors and predators. We investigated the trophic ecology of Olympic mudminnow to identify habitat and foraging specialization across three sites in Lake Ozette (Olympic National Park, Washington), and evaluate evidence for resource interactions with sympatric fish species. Stable isotopes of carbon and nitrogen from dominant co-occurring fish—yellow perch (Percaflavescens), prickly sculpin (Cottus asper), and northern pikeminnow (Ptychocheilus oregonensis)—were evaluated for evidence of competition with and predation on Olympic mudminnow using trophic niche overlap and stable isotope mixing models. Evidence from co-occurrence and isotope analyses supported spatial and trophic segregation of Olympic mudminnow, and reduced likelihood of competitive and predatory relationships. Of the sympatric fish examined, prickly sculpin may be the most likely to experience biotic interactions with Olympic mudminnow. These results are consistent with other research demonstrating strong habitat and microhabitat specialization by Olympic mudminnow and suggest that access to these favored habitats may be an important mediating factor in defining the potential for biotic interactions with other species, including nonnative fishes.

Development of skills in science communication is a well-acknowledged gap in graduate training, but the constraints that accompany research (limited time, resources, and knowledge of opportunities) make it challenging to acquire these proficiencies. Furthermore, advisors and institutions may find it difficult to support graduate students adequately in these efforts. The result is fewer career and societal benefits because students have not learned to communicate research effectively beyond their scientific peers. To help overcome these hurdles, we developed a practical approach to incorporating broad science communication into any graduate-school time line. The approach consists of a portfolio approach that organizes outreach activities along a time line of planned graduate studies. To help design the portfolio, we mapped available science communication tools according to 5 core skills essential to most scientific careers: writing, public speaking, leadership, project management, and teaching. This helps graduate students consider the diversity of communication tools based on their desired skills, time constraints, barriers to entry, target audiences, and personal and societal communication goals. By designing a portfolio with an advisor's input, guidance, and approval, graduate students can gauge how much outreach is appropriate given their other commitments to teaching, research, and classes. The student benefits from the advisors' experience and mentorship, promotes the group's research, and establishes a track record of engagement. When graduate student participation in science communication is discussed, it is often recommended that institutions offer or require more training in communication, project management, and leadership. We suggest that graduate students can also adopt a do-it-yourself approach that includes determining students' own outreach objectives and time constraints and communicating these with their advisor. By doing so we hope students will help create a new culture of science communication in graduate student education.

UNLABELLED: BACKGROUND/METHODOLOGY: A significant implication of increasing urbanization is anthropogenic noise pollution. Although noise is strongly associated with disruption of animal communication systems and negative health effects for humans, the study of these consequences at ecologically relevant spatial and temporal scales (termed soundscape ecology) is in early stages of application. In this study, we examined the above- and below-water soundscape of recreational and residential lakes in the region surrounding a large metropolitan area. Using univariate and multivariate approaches we test the importance of large- and local-scale landscape factors in driving acoustic characteristics across an urbanization gradient, and visualize changes in the soundscape over space and time. PRINCIPAL FINDINGS: Anthropogenic noise (anthrophony) was strongly predicted by a landcover-based metric of urbanization (within a 10 km radius), with presence of a public park as a secondary influence; this urbanization signal was apparent even in below-water recordings. The percent of hourly measurements exceeding noise thresholds associated with outdoor disturbance was 67%, 17%, and 0%, respectively, for lakes characterized as High, Medium, and Low urbanization. Decreased biophony (proportion of natural sounds) was associated with presence of a public park followed by increased urbanization; time of day was also a significant predictor of biophony. Local-scale (shoreline) residential development was not related to changes in anthrophony or biophony. The patterns we identify are illustrated with a multivariate approach which allows use of entire sound samples and facilitates interpretation of changes in a soundscape. CONCLUSIONS/SIGNIFICANCE: As highly valued residential and recreation areas, lakes represent everyday soundscapes important to both humans and wildlife. Our findings that many of these areas, particularly those with public parks, routinely experience sound types and levels associated with disturbance, suggests that urban planners need to account for the effect of increasing development on soundscapes to avoid compromising goals for ecological and human health.