Environmental DNA (eDNA) is a sensitive technique for early detection of rare species, including bighead (Hypophthalmichthys nobilis) and silver (Hypophthalmichthys molitrix) carp, which are ...incipient invaders of the Great Lakes. Since 2009, 2822 samples have been collected from the Great Lakes basin to delimit the extent of Asian carp incursions. Samples collected in the Chicago Area Waterway System and in the western basin of Lake Erie indicate the presence of Asian carp DNA in the Great Lakes. These positive eDNA detections are within 6 and 4 km from where bighead carps were recovered in Lake Calumet, near Lake Michigan (2010), and from Sandusky Bay, Lake Erie (2000), respectively. To implement a Great Lakes surveillance plan for protecting imperiled species and reducing damages from invasive species, federal, state, and provincial agencies will need to cooperatively plan and implement a surveillance program that employs the unique strengths of multiple sampling tools, including eDNA methods.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Environmental DNA (eDNA) is useful for delimiting species ranges in aquatic systems, whereby water samples are screened for the presence of DNA from a single species. However, DNA from many species ...is collected in every sample, and high-throughput sequencing approaches allow for more passive surveillance where a community of species is identified. In this study, we use active (targeted) and passive molecular surveillance approaches to detect species in the Muskingum River Watershed in Ohio, USA. The presence of bighead carp (Hypophthalmichthys nobilis) eDNA in the Muskingum River Watershed was confirmed with active surveillance using digital droplet polymerase chain reaction (ddPCR). The passive surveillance method detected the presence of eDNA from northern snakehead (Channa argus), which was further confirmed with active ddPCR. Whereas active surveillance may be more sensitive to detecting rare DNA, passive surveillance has the capability of detecting unexpected invasive species. Deploying both active and passive surveillance approaches with the same eDNA samples is beneficial for invasive species management.
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With increasing pressure placed on natural systems by growing human populations, both scientists and resource managers need a better understanding of the relationships between cumulative stress from ...human activities and valued ecosystem services. Societies often seek to mitigate threats to these services through large-scale, costly restoration projects, such as the over one billion dollar Great Lakes Restoration Initiative currently underway. To help inform these efforts, we merged high-resolution spatial analyses of environmental stressors with mapping of ecosystem services for all five Great Lakes. Cumulative ecosystem stress is highest in near-shore habitats, but also extends offshore in Lakes Erie, Ontario, and Michigan. Variation in cumulative stress is driven largely by spatial concordance among multiple stressors, indicating the importance of considering all stressors when planning restoration activities. In addition, highly stressed areas reflect numerous different combinations of stressors rather than a single suite of problems, suggesting that a detailed understanding of the stressors needing alleviation could improve restoration planning. We also find that many important areas for fisheries and recreation are subject to high stress, indicating that ecosystem degradation could be threatening key services. Current restoration efforts have targeted high-stress sites almost exclusively, but generally without knowledge of the full range of stressors affecting these locations or differences among sites in service provisioning. Our results demonstrate that joint spatial analysis of stressors and ecosystem services can provide a critical foundation for maximizing social and ecological benefits from restoration investments.
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In many North American rivers, populations of multiple species of non-native cyprinid fishes are present, including black carp (Mylpharyngodon piceus), grass carp (Ctenopharyngodon idella), bighead ...carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), common carp (Cyprinus carpio), and goldfish (Carassius auratus). All six of these species are found in the Mississippi River basin and tracking their invasion has proven difficult, particularly where abundance is low. Knowledge of the location of the invasion front is valuable to natural resource managers because future ecological and economic damages can be most effectively prevented when populations are low. To test the accuracy of environmental DNA (eDNA) as an early indicator of species occurrence and relative abundance, we applied eDNA technology to the six non-native cyprinid species putatively present in a 2.6 river mile stretch of the Chicago (IL, USA) canal system that was subsequently treated with piscicide. The proportion of water samples yielding positive detections increased with relative abundance of the six species, as indicated by the number of carcasses recovered after poisoning. New markers for black carp, grass carp, and a common carp/goldfish are reported and details of the marker testing to ensure specificity are provided.
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Environmental DNA (eDNA) surveillance holds great promise for improving species conservation and management. However, few studies have investigated eDNA dynamics under natural conditions, and ...interpretations of eDNA surveillance results are clouded by uncertainties about eDNA degradation. We conducted a literature review to assess current understanding of eDNA degradation in aquatic systems and an experiment exploring how environmental conditions can influence eDNA degradation. Previous studies have reported macrobial eDNA persistence ranging from less than 1 day to over 2 weeks, with no attempts to quantify factors affecting degradation. Using a SYBR Green quantitative PCR assay to observe Common Carp (Cyprinus carpio) eDNA degradation in laboratory mesocosms, our rate of Common Carp eDNA detection decreased over time. Common Carp eDNA concentration followed a pattern of exponential decay, and observed decay rates exceeded previously published values for aquatic macrobial eDNA. Contrary to our expectations, eDNA degradation rate declined as biochemical oxygen demand, chlorophyll, and total eDNA (i.e., from any organism) concentration increased. Our results help explain the widely divergent, previously published estimates for eDNA degradation. Measurements of local environmental conditions, consideration of environmental influence on eDNA detection, and quantification of local eDNA degradation rates will help interpret future eDNA surveillance results.
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Impacts of nonindigenous crayfishes on ecosystem services exemplify the mixture of positive and negative effects of intentionally introduced species. Global introductions for aquaculture and ...ornamental purposes have begun to homogenize naturally disjunct global distributions of crayfish families. Negative impacts include the loss of provisioning (e.g., reductions in edible native species, reproductive interference or hybridization with native crayfishes), regulatory (e.g., lethal disease spread, increased costs to agriculture and water management), supporting (e.g., large changes in ecological communities), and cultural (e.g., loss of festivals celebrating native crayfish) services. Where quantification of impacts exists (e.g.,
Procambarus clarkii
and
Pacifastacus leniusculus
in Europe), regulations now prohibit introduction and spread of crayfishes, indicating that losses of ecosystem services have outweighed gains. Recent research advances such as predicting invasiveness, predicting spread, improved detection and control, and bioeconomic analysis to increase cost-effectiveness of management could be employed to reduce future losses of ecosystem services.
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BFBNIB, INZLJ, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK, ZRSKP
At least 65 aquatic plant species have been identified as part of a surveillance list of non-native species that pose a threat to biodiversity and ecosystem services in the Laurentian Great Lakes. ...Early detection of these potentially invasive aquatic plants (IAP) could minimize impacts of novel incursions and facilitate successful eradication. We developed, implemented, and then adaptively refined a probabilistic boat-based sampling design that aimed to maximize the likelihood of detecting novel IAP incursions in large (400+ hectares) Great Lakes coastal areas. Surveys were conducted from 2017 to 2019 at five Great Lakes locations - St Joseph River (MI), Saginaw River (MI), Milwaukee (WI), Cleveland (OH), and the Detroit River (MI). Aquatic plant communities were characterized across the five sites, with a total of 61 aquatic plant species detected. One-fifth of the species detected in our surveys were non-native to the Great Lakes basin. Sample-based species rarefaction curves, constructed from detection data from all surveys combined at each location, show that the estimated sample effort required for high confidence (> 95%) detection of all aquatic plants at a site, including potentially invasive species, varies (< 100 sample units for Detroit River; > 300 sample units for Milwaukee, roughly equivalent to 6 to 18 days sampling effort, respectively). At least 70% of the estimated species pool was detected at each site during initial 3-day surveys. Leveraging information on detection patterns from initial surveys, including depth and species richness strata, improved survey efficiency and completeness at some sites, with detection of at least 80% of the estimated species pool during subsequent surveys. Based on a forest-based classification and regression method, a combination of just five variables explained 70% or more of the variation in observed richness at all sites (depth, fetch, percent littoral, distance to boat ramps and distance to marinas). We discuss how the model outcomes can be used to inform survey design for other Great Lakes coastal areas. The survey design we describe provides a useful template that could be adaptively improved for early detection of IAP in the Great Lakes.
In an effort to harmonize multi-jurisdictional surveillance and detection of aquatic invasive species, regional stakeholders have called for the development of a Great Lakes Aquatic Invasive Species ...Surveillance Framework to identify species that pose a risk to the basin, quantify the relative risk of various pathways of introduction, provide guidance on monitoring protocols for surveillance, and identify priority locations for surveillance based on this pathway assessment. Here, we screen 448 species to develop a surveillance list of 144 species that are relevant for Great Lakes surveillance: are not yet widespread throughout the basin, have a pathway through which they can arrive, are able to establish and are predicted to cause impacts. Using the Great Lakes Aquatic Nonindigenous Species Risk Assessment for consistent assessment across taxa, the surveillance species list consisted of 144 species: 64 plants, 4 algae, 40 fish, 5 mollusks, 28 crustaceans, 1 platyhelminthes and 2 bryozoans. While pathway risk varies by taxon, the highest risk pathways across all taxonomic groups are natural dispersal, hitchhiking/fouling, and intentional release. The taxonomic group predicted to have the most severe impacts on a per species basis is algae, followed by mollusks, and plants. However, the large number of plant and fish species on the surveillance species list means that overall predicted impact (from a taxonomic perspective) is greatest from these two groups. We recommend ways that the surveillance list could be applied to improve aquatic invasive species management efforts: engage in community-based surveillance, inform taxonomic and species surveillance priorities, provide guidance on monitoring protocols for surveillance, quantify the relative risk of various pathways of introduction and identify priority locations for surveillance based on this pathway assessment.
Trailered boats have been implicated in the spread of aquatic invasive species. There has been, however, little empirical research on the type and quantity of aquatic invasive species being ...transported, nor on the efficacy of management interventions (e.g., inspection crews, boat washing). In a study of small‐craft boats and trailers, we collected numerous aquatic and terrestrial organisms, including some species that are morphologically similar to known aquatic invasive species. Additionally, a mail survey of registered boaters (n = 944, 11% response rate) and an in‐person survey of boaters in the field (n = 459, 90% response rate) both indicated that more than twothirds of boaters do not always take steps to clean their boats. Furthermore, we used a controlled experiment to learn that visual inspection and hand removal can reduce the amount of macrophytes on boats by 88% ± 5% (mean ± SE), with high‐pressure washing equally as effective (83% ± 4%) and low‐pressure washing less so (62% ± 3% removal rate). For removing small‐bodied organisms, high‐pressure washing was most effective with a 91% ± 2% removal rate; low‐pressure washing and hand removal were less effective (74% ± 6% and 65% ± 4% removal rates, respectively). This research supports the widespread belief that trailered boats are an important vector in the spread of aquatic invasive species, and suggests that many boaters have not yet adopted consistent and effective boat cleaning habits. Therefore, additional management efforts may be appropriate.
Resumen
Los botes con remolque han sido implicados en la dispersión de especies acuáticas invasivas. Sin embargo, se ha llevado a cabo poca investigación empírica acerca del tipo y cantidad de especies acuáticas invasivas que están siendo transportadas así como de la eficacia del manejo a este respecto (p.e. tripulación para inspección y lavado de botes). En un estudio realizado acerca de pequeñas embarcaciones y remolques, se colectaron numerosos organismos acuáticos y terrestres, incluyendo algunas especies que son morfológicamente similares a especies acuáticas invasivas previamente conocidas. Adicionalmente se hizo un sondeo por correo a los dueños registrados de las embarcaciones (n = 944, 11% de tasa de respuesta) y un sondeo en persona en campo (n = 459, 90% tasa de respuesta). Ambos sondeos indicaron que más de dos tercios de dichos dueños no siempre limpian sus botes. Más aún, se hizo un experimento en condiciones controladas para determinar que la inspección visual y la remoción manual pueden reducir la cantidad de macrofitas en los botes hasta en un 88% ± 5% (media ± EE), siendo igualmente efectivo el lavado a alta presión (83% ± 4%) mientras que el lavado a baja presión no lo fue tanto (62% ± 3% tasa de remoción). En cuanto a la remoción de animales pequeños, el lavado a alta presión fue el más efectivo con un 91% ± 2% de tasa de remoción; el lavado con baja presión y la remoción manual fueron menos efectivos (74% ± 6% y 65% ± 4% de tasa de remoción, respectivamente). Este estudio apoya la creencia común que los botes con remolque son un vector importante en la dispersión de especies acuáticas invasivas; se sugiere, además, que muchos dueños de botes aun no han adoptado hábitos de limpieza consistentes y efectivos. Por lo resultan adecuados esfuerzos de manejo adicionales.
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Following decades of ecologic and economic impacts from a growing list of nonindigenous and invasive species, government and management entities are committing to systematic early- detection ...monitoring (EDM). This has reinvigorated investment in the science underpinning such monitoring, as well as the need to convey that science in practical terms to those tasked with EDM implementation. Using the context of nonindigenous species in the North American Great Lakes, this article summarizes the current scientific tools and knowledge – including limitations, research needs, and likely future developments – relevant to various aspects of planning and conducting comprehensive EDM. We begin with the scope of the effort, contrasting target-species with broad-spectrum monitoring, reviewing information to support prioritization based on species and locations, and exploring the challenge of moving beyond individual surveys towards a coordinated monitoring network. Next, we discuss survey design, including effort to expend and its allocation over space and time. A section on sample collection and analysis overviews the merits of collecting actual organisms versus shed DNA, reviews the capabilities and limitations of identification by morphology, DNA target markers, or DNA barcoding, and examines best practices for sample handling and data verification. We end with a section addressing the analysis of monitoring data, including methods to evaluate survey performance and characterize and communicate uncertainty. Although the body of science supporting EDM implementation is already substantial, research and information needs (many already actively being addressed) include: better data to support risk assessments that guide choice of taxa and locations to monitor; improved understanding of spatiotemporal scales for sample collection; further development of DNA target markers, reference barcodes, genomic workflows, and synergies between DNA-based and morphology-based taxonomy; and tools and information management systems for better evaluating and communicating survey outcomes and uncertainty.
•Article summarizes the state of the science for early-detection monitoring.•Contrast of monitoring to detect a priority species vs many species (broad spectrum).•Early detection requires high survey effort; design refinement can improve efficiency.•DNA-based ID technology is rapidly evolving, complementary to morphology ID.•Tools exist for formal survey performance and uncertainty assessment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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