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At least 235 records · Page 13Linked to original sources
USGS2012

The Fort Collins Science Center

With a focus on biological research, the U.S. Geological Survey Fort Collins Science Center (FORT) develops and disseminates science-based information and tools to support natural resource decision-making. This brochure succinctly describes the integrated science capabilities, products, and services that the FORT science community offers across the disciplines of aquatic systems, ecosystem dynamics, information science, invasive species science, policy analysis and social science assistance, and trust species and habitats.

Colorado↗
USGS2015

Determination of the acute toxicity of isoniazid to three invasive carp species and rainbow trout in static exposures

Three invasive fishes of considerable concern to aquatic resource managers are the Hypophthalmichthys nobilis (bighead carp), Hypophthalmichthys molitrix (silver carp), and Ctenopharyngodon idella (grass carp), collectively known as Asian carps. There is a need for an effective chemical control agent for Asian carps. Isoniazid was identified as a potential toxicant for grass carp. The selective toxicity of isoniazid to grass carp was verified as a response to an anecdotal report received in 2013. In addition, the toxicity of isoniazid to bighead carp, silver carp, and Oncorhynchus mykiss (rainbow trout) was evaluated. Isoniazid was not toxic to grass carp at the reported anecdotal concentration, which was 13 milligrams per liter. Isoniazid (130 milligrams per liter) was not selectively toxic to bighead carp, silver carp, or grass carp when compared to rainbow trout.

Open-File Report↗
USGS2022

The role of hydraulic and geomorphic complexity in predicting invasive carp spawning potential: St. Croix River, Minnesota and Wisconsin, United States

Since they were first introduced to the United States more than 50 years ago, invasive carp have rapidly colonized rivers of the Mississippi River Basin, with detrimental effects on native aquatic species. Their continued range expansion, and potential for subsequent invasion of the Great Lakes, has led to increased concern for the susceptibility of as-yet uncompromised lotic and lentic systems in the central United States. Because invasive carp eggs and larvae must drift in the river current for the first several days following spawning, numerical drift modeling has emerged as a useful technique for determining whether certain river systems and reaches have the potential to support suspension-to-hatching survival of invasive carp eggs, a critical first step in recruitment. Here we use one such numerical modeling approach, the Fluvial Egg Drift Simulator (FluEgg), to estimate bighead carp ( Hypophthalmichthys nobilis ) egg hatching success and larval retention in a 47.8-kilometer (km) reach of the multi-thread St. Croix River, Minnesota and Wisconsin, United States. We explore three approaches for obtaining the hydraulic data required by FluEgg, parameterizing the model with either (a) field hydraulic data collected within the main channel during a high-flow event, or hydraulic data output from a one-dimensional hydrodynamic model with both (b) steady, and (c) unsteady flows. We find that the three approaches, along with the range of water temperatures and discharge used in simulations, produce vastly different predictions of streamwise transport and in-river egg hatching probability (0% for field data, 0 to 96% for steady-state hydraulic modeling, and 1.8 to 65% for unsteady modeling). However, all FluEgg simulations, regardless of the source of hydraulic data, predicted that no larvae reach the gas bladder inflation stage within the study reach where nursery habitat is abundant. Overall, these results indicate that the lower St. Croix River is suitable for invasive carp spawning and egg suspension until hatching for a range of discharge and water temperatures. These results highlight the role of complex channel hydraulics and morphology, particularly multi-thread reaches, and their inclusion in ecohydraulic-suitability modeling to determine susceptibility of river systems for invasive carp reproduction. Our work also emphasizes the scientific value of multi-dimensional hydrodynamic models that can capture the spatial heterogeneity of flow fields in geomorphically complex rivers. This work may help to guide management efforts based on the targeted monitoring and control and improve invasive carp egg and larvae sampling efficiency.

Minnesota, Wisconsin↗
USGS2018

Large-scale variation in density of an aquatic ecosystem indicator species

Monitoring indicator species is a pragmatic approach to natural resource assessments, especially when the link between the indicator species and ecosystem state is well justified. However, conducting ecosystem assessments over representative spatial scales that are insensitive to local heterogeneity is challenging. We examine the link between polychlorinated biphenyl (PCB) contamination and population density of an aquatic habitat specialist over a large spatial scale using non-invasive genetic spatial capture-recapture. Using American mink (Neovison vison), a predatory mammal and an indicator of aquatic ecosystems, we compared estimates of density in two major river systems, one with extremely high levels of PCB contamination (Hudson River), and a hydrologically independent river with lower PCB levels (Mohawk River). Our work supports the hypothesis that the mink densities are substantially (1.64-1.67 times) lower in the contaminated river system. We demonstrate the value of coupling the indicator species concept with well-conceived and spatially representative monitoring protocols. PCBs have demonstrable detrimental effects on aquatic ecosystems, including mink, and these effects are likely to be profound and long-lasting, manifesting as population-level impacts. Through integrating non-invasive data collection, genetic analysis, and spatial capture-recapture methods, we present a monitoring framework for generating robust density estimates across large spatial scales.

New York↗
USGS2025

Designing sortable guilds for multispecies selective fish passage

The importance of connectivity for freshwater organisms is widely recognised, yet in-stream barriers associated with population declines and increased risk of extinction remain globally ubiquitous. Despite their negative consequences, these barriers can protect aquatic communities by limiting the spread of invasive species, leading to conflicting management goals in some regions. Selective fish passage is a solution for the conflicting goals of passing native, desirable species while restricting the spread of invasives. Approaches that can target groups of species sharing similar attributes (i.e. guilds) are likely to be more efficient than those that target species individually, particularly in taxonomically diverse systems. We explored the guild structure of 220 Great Lakes freshwater fishes based on morphological, phenological, physiological and behavioural attributes associated with passage and movement. We identified five distinct guilds as well as the attributes most important for defining these groupings: maximum total length, trophic level, relative eye size, spawning temperature, spawning season, presence/absence of ampullary electroreceptors and the presence/absence of hearing specialisations. The approaches outlined in this work can be generalised to enhance selective fish passage in aquatic ecosystems worldwide.

Fish and Fisheries↗
USGS2023

Estimates of predator densities using mobile DIDSON surveys: Implications for survival of Central Valley Chinook Salmon

The Sacramento–San Joaquin Delta (hereafter, “the Delta”) is one of the estuaries with the most invasive species in the world, and nonnative predators may be a major factor in the observed decline of Central Valley Chinook Salmon Oncorhynchus tshawytscha over recent decades. In order for managers to take actions that might reduce predation-related mortality for these ecologically, culturally, and economically valuable fish, it is important to understand the factors influencing the distribution and abundance of piscivores in the Delta. In this study, we used a dual-frequency identification sonar (i.e., DIDSON) to conduct mobile surveys to quantify the abundances of piscivores in the Delta. We then used these data to identify the habitat features that are correlated with the abundance of piscivores. Prior to conducting the surveys, we used DIDSON data from captured fish to develop an algorithm to distinguish piscivores from nonpiscivores with high confidence (98% accuracy). A generalized linear mixed-effects model fit to these survey data indicated that predator abundances were most associated with areas of increased submerged aquatic vegetation patches, and channels that are straighter, with increased bathymetric complexity. When applied to the entire survey area, this model was successfully able to predict known areas of high predator densities. These results indicate that one approach to reduce predator densities in key locations throughout the Delta, and improve juvenile salmonid outmigration survival, is to reduce the extent of invasive submerged aquatic vegetation. Because experimental predator removals have been largely ineffective in the Delta, efforts to manipulate habitat to discourage nonnative predator recruitment and favor native species recruitment may provide a more effective solution to improve salmonid survival rates.

California↗
USGS2021

Emerging control strategies for integrated pest management of invasive carps

Invasive carps are ecologically and economically problematic fish species in many large river basins in the United States and pose a threat to aquatic ecosystems throughout much of North America. Four species of invasive carps: black carp ( Mylopharyngodon piceus ), grass carp ( Ctenopharyngodon idella ), silver carp ( Hypophthalmichthys molitrix ) and bighead carp ( Hypophthalmichthys nobilis ), are particularly concerning for native ecosystems because they occupy and disrupt a variety of food and habitat niches. In response, natural resource agencies are developing integrated pest management (IPM) plans to mitigate invasive carps. Control tools are one key component within a successful IPM program and have been a focal point for development by governmental agencies and academic researchers. For example, behavioural deterrents and barriers that block migratory pathways could limit carps range expansion into new areas, while efficient removal methods could suppress established carp populations. However, control tools are sometimes limited in practice due to uncertainty with deployment, efficacy and availability. This review provides an overview of several emerging modelling approaches and control technologies that could inform and support future invasive carp IPM programs.

Journal of Vertebrate Biology↗
USGS2009

Fort Collins Science Center - Fiscal Year 2008 Science Accomplishments

Public land and natural resource managers in the United States are confronted with increasingly complex decisions that have important ramifications for both ecological and human systems. The scientists and technical professionals at the U.S. Geological Survey (USGS) Fort Collins Science Center (FORT) contribute a unique blend of ecological, socioeconomic, and technological expertise to investigating complicated ecological problems that address critical management questions. In Fiscal Year 2008 (FY08), FORT's scientific and technical professionals continued research vital to the science and management needs of U.S. Department of the Interior agencies and other entities. This annual report describes select FY08 accomplishments in research and technical assistance involving biological information management and delivery; aquatic, riparian, and managed-river ecosystems; invasive species; status and trends of biological resources (including human dimensions and social science); terrestrial ecosystems; and fish and wildlife resources.

Open-File Report↗
USGS2026

Integrating habitat suitability and climate constraints to predict nonnative fish invasion risk for U.S. streams and inland lakes

Introduction: Nonnative fishes in streams and inland lakes can substantially alter aquatic ecosystems by degrading habitat conditions, competing with native species, and restructuring food webs. Identifying invasion hotspots can inform proactive management and prevention of nonnative species establishment. Methods: In this study, we identified streams and lakes across the conterminous United States that are vulnerable to invasion by 18 nonnative stream and 28 nonnative lake fish species. Habitat suitability models were developed separately for stream and lake species across nine ecoregions using natural and anthropogenic predictors, and species occurrences were predicted by integrating model results with climate match scores based on comparisons between environmental conditions in species’ native and potential nonnative ranges. We classified areas with both high habitat suitability and strong climate similarity as having high invasion potential and generated hotspot maps by stacking species-level predictions. Results: Florida exhibits the highest invasion risk for both habitat types. Stream hotspots were concentrated near major metropolitan areas, whereas lake hotspots were more widely distributed across the Great Lakes basin and the northeastern U.S. Twelve species were predicted to invade both habitat types, with goldfish ( Carassius auratus ) and pirapitinga ( Piaractus brachypomus ) showing particularly high invasion potential. Discussion: These findings provide a comprehensive assessment of nonnative freshwater fish invasion risk and support targeted monitoring and management strategies.

conterminous United States↗
USGS2024

Understanding gaps in early detection of and rapid response to invasive species in the United States: A literature review and bibliometric analysis

While concepts regarding invasive species establishment patterns and eradication possibilities have long been a topic of invasion biology, the specific terminology referring to early detection of and rapid response to (EDRR) invasive species emerged in scientific literature during the early 2000s. Since then, the EDRR approach has expanded to include a suite of detection, planning, and management tools. By conducting a systematic literature review, we attempt to characterize the field of EDRR in the United States and its territories as reflected by publication records. Specifically, we assessed publication data such as the number of publications per year, the most common journals where papers were published, and the relationship between author’s keywords for studies focusing on aquatic and terrestrial habitats. For publications that used invasive species occurrence or abundance data (whether collected for the purposes of the respective publication or acquired from another data source), we manually vetted additional information such as focal taxa, data collection years and locations, sources of other data used, and whether data or code were deposited in open access formats. We also conducted network analyses for the author institutions that coauthored papers together most frequently and for the references most cited by EDRR publications. Overall, we found that silos existed in terms of which author institutions worked together, which existing literature was cited, and which topics were frequently explored. We also found evidence of substantial gaps in data access and use. For example, although a wide variety of data sources for invasive species occurrences are available, these sources were seldom cited by published literature, and newly collected data was not often deposited into invasive species databases or other open-source data repositories. Considering the continued advocation for a centralized national EDRR information system, our study suggests that facilitating access to data, decision support tools, and other informational resources represents a key opportunity for improving EDRR capabilities.

Ecological Informatics↗
USGS2024

Spatial distribution patterns of invasive silver carp can inform removal efforts in an oxbow lake of the Mississippi River

Oxbow lakes are highly productive waterbodies that host multiple life stages of many freshwater aquatic species. These lakes also provide foraging and rearing habitat to the invasive silver carp ( Hypophthalmichthys molitrix ) enabling populations to grow in biomass and abundance that can add propagule pressure to connected waterways and oxbows within the Mississippi River Basin. Ecologically these fish are undesirable because they overlap in diet and may compete for resources with native fishes and negatively impact recreational fisheries. Our goal was to evaluate silver carp distribution patterns in a major Mississippi River oxbow lake to inform removal programs and precision harvesting. We implanted 35 adult silver carp with acoustic tags and released them into the lake. Periodic tracking over 365 d revealed that fish were predominantly found in lake areas with water depths ranging from 2.0 to 5.9 m during all seasons, despite the availability of shallower and deeper water. Silver carp tended to aggregate in the wintertime (December–February) relative to other seasons. This information about lake area uses and seasonal aggregations could inform removal efforts in invaded waterbodies by exploiting natural behavioral and temporal vulnerabilities of this highly invasive and difficult-to-capture fish.

Mississippi↗
USGS2015

Effectiveness of two commercial rotenone formulations in the eradication of virile crayfish Orconectes virillis

The virile or northern crayfish Orconectes virilis is an invasive species throughout much of the USA, damaging aquatic communities where it is introduced. Therefore, identification of effective methods for its eradication from areas in which it is unwanted is important. We studied the effectiveness of two commercial formulations of rotenone, Chem Fish Regular and CFT Legumine, for virile crayfish control. Although both formulations were effective for fish eradication, earlier observations by fisheries managers suggested that the relative effectiveness of the two formulations differs for crayfish. The only noteworthy difference between the formulations is that the former contains a synergist. In our first experiment, we tested each toxicant at the maximum labeled dosage (5 ppm) and found CFT Legumine to be 100% ineffective (0% mortality), while the Chem Fish Regular treatment resulted in 12.5% mortality. After we deemed Chem Fish Regular to be the only toxicant with any effectiveness against virile crayfish, we tested concentrations from 5 to 50 ppm and found 10 times the maximum labeled dosage (50 ppm rotenone) was needed to kill all virile crayfish. Because crayfish burrow and can leave water, and because 100% eradication is usually desired, rotenone applied at the labeled rates will not be effective for crayfish control. However, treating a body of water with CFT Legumine to eradicate invasive fish while leaving desirable crayfish unharmed is possible.

North American Journal of Fisheries Management↗
USGS2023

Is chemical control for crayfish in hatchery fish shipments practical?

Invasive crayfish (family Cambaridae) displace native crayfish species and alter aquatic habitat, community structure, and ecosystem function. We evaluated whether chemical control can be a reliable control agent for crayfish to ensure that shipments from fish hatcheries did not result in new infestations of invasive crayfish. A series of acute (≤1 h) toxicity tests were conducted to evaluate the toxicity of cypermethrin and pyrethrin to crayfish, freshwater mussels, and fish; chemical concentrations in test organisms; effectiveness of carbon-block filters to remove cypermethrin from test waters; and the cost of chemical control relative to extra handling of fish. Cypermethrin dosed at 75 μg/L for 15 min resulted in 100% mortality of adult white river crawfish Procambarus acutus and virile crayfish Faxonius virilis but did not cause >20% mortality in adult pondmussel Ligumia subrostrata , juvenile fatmucket Lampsilis siliquoidea , fingerling Bluegill Lepomis macrochirus , hybrid sunfish (Bluegill × Green Sunfish L. cyanellus ), hybrid Striped Bass (White Bass Morone chrysops × Striped Bass M. saxatilis ), yearling Paddlefish Polyodon spathula, or ready-to-eat Bluegill, hybrid sunfish, and Channel Catfish Ictalurus punctatus . Behavioral effects, such as loss of equilibrium or head shaking, were generally limited to 1 h postexposure. Mean concentrations of cypermethrin increased in fish fillets (4–26 μg/g) and whole fish (5–1,770 μg/g); therefore, regulations limiting harvest for up to 7 d following stocking may be required. A carbon-block filtration system was effective in reducing (<90%) cypermethrin concentrations and thus reducing potential effects to nontarget species in receiving waters. Extra handling of fish was more cost-effective for all fish tested except for Paddlefish, where the cost of chemical control was half that for extra handling. For all other fish tested, chemical control was 4–10 times more expensive than extra handling. Special use permits or chemical registration are needed before chemical control for crayfish could be routinely used at fish hatcheries.

North American Journal of Aquaculture↗
USGS2025

Combined effectiveness of light and bait to enhance trapping for monitoring and removal of invasive crayfish: Virile crayfish example

Invasive populations of crayfish are a major threat to native aquatic ecosystems around the world. The virile crayfish ( Faxonius virilis ) has become problematic outside of its native range in North America. Use of minnow traps is a common method used to detect the presence of and reduce invasive crayfish numbers. The primary goal of this study was to determine if the effectiveness and practicality of control through trapping for invasive crayfish could be significantly improved with the addition of lights. From this study, we found virile crayfish were attracted to white light and avoided blue light in the laboratory. In pond trials, traps with white or blue lights had catch per unit effort (CPUE) greater than traps without light, and traps with white lights had a CPUE nearly twice that of traps with blue lights. The addition of white lights to traps with food led to a nearly three-fold increase in CPUE than white light alone or two-fold for food bait alone. We found a continued decline in capture rates from the same pond over 3 days of trapping where captured crayfish were not returned to the pond. The continued decline in catch rate of new individuals suggests that our trapping may have been having a significant effect on the density of crayfish remaining in the pond. In addition, the size distribution of the crayfish collected during these trapping studies showed that the effort appears to be effective at collecting both juvenile and adult crayfish across almost all sizes. This would suggest that the combination of white light and bait is effective in the management of invasive crayfish populations.

Management of Biological Invasions↗
USGS2025

Freshwater gastropod (Mollusca: Gastropoda) assemblages, habitat, and the first detection of an invasive gastropod species in two large, dreissenid-influenced, connecting rivers

Native freshwater gastropods are a highly diverse and imperiled group of mollusks in North America and are influenced by a growing number of problematic invasive species. Consequently, there has been an increased need for understanding aquatic gastropod assemblages throughout North America to implement conservation and management strategies. In the Laurentian Great Lakes, gastropod surveys have been sparse, and most surveys have focused on invasive species. To investigate gastropod assemblages in two large connecting rivers of the Great Lakes, the Detroit and St. Clair rivers, benthic surveys were conducted in 2019 and 2021. Sites in the Detroit River (n = 56) and the St. Clair River (n = 51) were surveyed using petite PONAR grabs from which gastropod shells were identified and quantified to family or a group of two combined families. In both the Detroit and St. Clair rivers, the gastropod family Pleuroceridae (37 % and 56 % total composition, respectively) and combined families Amnicolidae + Hydrobiidae (42 % and 23 % total composition, respectively) contributed the most to overall gastropod composition. Invasive Potamopyrgus antipodarum shells were identified at 4 (7 %) Detroit River sites and 10 (20 %) St. Clair River sites and represent the first documented occurrence in the Detroit River. Although this study was limited to quantifying densities based on shells and cannot assume live-collected snail densities, these results provide a baseline knowledge of the gastropod assemblages and habitat use in these two large river systems which can be used to implement conservation and management strategies.

Detroit River, St. Clair River↗
USGS2013

Challenge theme 1: Understanding and preserving ecological resources: Chapter 3 in United States-Mexican Borderlands: Facing tomorrow's challenges through USGS science

The notable biodiversity within the United States–Mexican border region is driven by the wide variety of natural landscapes in the area and its biologically unique transition zone of habitats for xeric, temperate, and subtropical species. Six diverse ecoregions cover the length of the border (fig. 3–1): California Coastal Sage, Chaparral, and Oak Woodlands; Sonoran Desert; Madrean Archipelago; Chihuahuan Desert; Southern Texas Plains; and Western Gulf Coastal Plain. The unique geology and many of the distinctive geographic features and climatic conditions that have given rise to the diverse populations of plants and animals found in the Borderlands also attract human populations. The number of people living in the Borderlands has increased dramatically over recent years, from about 7 million in 1980 to almost 12 million in 2003; the population is estimated to be more than 18 million by 2020 (Peach and Williams, 2003). The human population increase and associated change in land use have contributed to habitat fragmentation and habitat loss for native species, thus threatening their survival. Some ways in which humans negatively affect plants and animals in the Borderlands include dewatering of aquatic ecosystems, water pollution, introduction and spread of invasive species, outdoor lighting, military and border enforcement activity, and energy development and transmission.

United States-Mexico Borderlands↗
USGS2025

Impacts of flowering rush (Butomus umbellatus L.) on macrophyte diversity and composition in the Upper Mississippi River

Flowering rush ( Butomus umbellatus L.), a perennial plant native to Eurasia, made a widespread appearance in the Upper Mississippi River in the United States in 2020, following extremely high river discharge during the previous year. Flowering rush expanded rapidly and was found at 1–10% of sites (n = 6,630 total sites) across a 400 km river reach within the first 4 years of invasion. Flowering rush invaded at least 12 of 31 wetland vegetation classes, including submersed aquatic, rooted-floating, deep marsh, and shallow marsh. Analysis of long-term macrophyte data and our targeted field study revealed that plant diversity declined with greater abundance of flowering rush over a 4-year early invasion period, suggesting that native species were displaced. Furthermore, species correlation plots showed a significant negative correlation (r < -0.1) between flowering rush and several native species, including wild celery, water stargrass, and wild rice. Non-metric multi-dimensional scaling (NMDS) ordination placed flowering rush near the center of the plot, which may indicate tolerance to a wide range of environmental conditions such as water depth, flow, and substrate. Centering on the NMDS plot also shows that flowering rush invades many types of vegetated aquatic land cover classes, which was also supported by our geographic information systems analysis of land cover invasion. These habitat associations and ecological impacts of the recent, widespread invasion of flowering rush in the Upper Mississippi River can help inform restoration and management actions during early invasion. Continuing long-term data collection can break limitations on modeling cause-effect relationships and provide insights to the future ecological trajectory of the macrophyte community to this non-native invasive species.

Illinois, Iowa, Minnesota, Wisconsin↗
USGS2017

Effects of flood inundation and invasion by Phalaris arundinacea on nitrogen cycling in an Upper Mississippi River floodplain forest

Although floodplains are thought to serve as important buffers against nitrogen (N) transport to aquatic systems, frequent flooding and high levels of nutrient availability also make these systems prone to invasion by exotic plant species. Invasive plants could modify the cycling and availability of nutrients within floodplains, with effects that could feedback to promote the persistence of the invasive species and impact N export to riverine and coastal areas. We examined the effect of flooding on soil properties and N cycling at a floodplain site in Pool 8 of the Upper Mississippi River with 2 plant communities: mature native forest ( Acer saccharinum ) and patches of an invasive grass ( Phalaris arundinacea ). Plots were established within each vegetation type along an elevation gradient and sampled throughout the summers of 2013 and 2014. Spatial trends in flooding resulted in higher soil organic matter, porosity, and total nitrogen and carbon in low elevations. Nutrient processes and NH 4 + and NO 3 − availability, however, were best explained by vegetation type and time after flooding. Phalaris plots maintained higher rates of nitrification and higher concentrations of available NH 4 + and NO 3 − . These results suggest that invasion by Phalaris may make nitrogen more readily available and could help to reinforce this species' persistence in floodplain wetlands. They also raise the possibility that Phalaris may decrease floodplain N storage capacity and influence downstream transport of N to coastal zones.

Wisconsin↗