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Sequestered in his blitz-battered Regent's Park house in 1944, the ailing Herbert George Wells looks back on a life crowded with incident, books and women. Has it been a success for failure ? Once he was the most famous writer in the world, now he is a man deserted by his readers and depressed by the collapse of his utopian dreams. He recalls his life as a socialist, an acclaimed novelist and a feminist womaniser.

The technological innovation of environmental DNA(eDNA) began about 14 years ago with the detection of DNA from American bullfrogs (Lithobates catesbeianus, formerly Rana catesbeiana) in water samples from French ponds. Hundreds of journal publications later, many research groups have continued to innovate, expanding the genetic information derived from field samples. What started with the detection of a single target species now extends to detecting hundreds of species simultaneously. and to quantifying genetic diversity and population size (Andres et al. 2021). Terrestrial animals and plants are now also targeted from eDNA in water, soil, and air samples. The rapid pace of research has fueled many studies of management relevance, including detection of incipient invasions to guide control efforts detection of imperiled species to facilitate habitat protection; quantification of biodiversity trends over large spatial scales; and, in Europe, monitoring of indicator species or entire biological communities to establish baselines for environmental impact. Deployment of eDNA technology improves measurements of biodiversity, which could enable better management.

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.

The introduction and establishment of nonindigenous species (NIS) through global ship movements poses a significant threat to marine ecosystems and economies. While ballast-vectored invasions have been partly addressed by some national policies and an international agreement regulating the concentrations of organisms in ballast water, biofouling-vectored invasions remain largely unaddressed. Development of additional efficient and cost-effective ship-borne NIS policies requires an accurate estimation of NIS spread risk from both ballast water and biofouling. We demonstrate that the first-order Markovian assumption limits accurate modeling of NIS spread risks through the global shipping network. In contrast, we show that higher-order patterns provide more accurate NIS spread risk estimates by revealing indirect pathways of NIS transfer using Species Flow Higher-Order Networks (SF-HON). Using the largest available datasets of non-indigenous species for Europe and the United States, we then compare SF-HON model predictions against those from networks that consider only first-order connections and those that consider all possible indirect connections without consideration of their significance. We show that not only SF-HONs yield more accurate NIS spread risk predictions, but there are important differences in NIS spread via the ballast and biofouling vectors. Our work provides information that policymakers can use to develop more efficient and targeted prevention strategies for ship-borne NIS spread management, especially as management of biofouling is of increasing concern.

The Chicago Area Waterway System (CAWS) connects the Great Lakes watershed with the Mississippi watershed via canals that withdraw water from Lake Michigan. From 2009 through 2011, collaborators and I provided research, development, and application of eDNA to invasive species management in the CAWS in cooperation with the US Army Corps of Engineers (USACE). The research team's approach was a high‐stakes test of a novel combination of proven technologies (field sampling techniques and laboratory genetics). In the first application of eDNA to a large scale, urgent management goal, we quickly discovered eDNA of two species of bigheaded carps in parts of the waterway where traditional tools had not captured fish. The central research question was whether the sensitivity (probability of detecting a fish when it was present) of eDNA was higher than that of traditional fish sampling tools (e.g., nets, electrofishing). The effort was part of what became a very large, complex, on‐going initiative to reduce access by invasive species to Lake Michigan. This immediately garnered much attention, initiating a dialog about the reliability of eDNA, public discussion about the benefits and costs of the CAWS, and skepticism from industries that use the CAWS. Government agencies formed the Asian Carp Rapid Response Workgroup, which eventually became the Invasive Carp Regional Coordinating Committee (ICRCC). The ICRCC continues its coordinating role on the use of eDNA and other management responses in the CAWS. With the benefit of hindsight, I draw several lessons from the experience that may help in other settings where eDNA is now being deployed with increasing confidence and acceptance; evaluate the on‐going CAWS surveillance and management effort; and recommend strengthening the current approach by broadening and deepening participation in a collaborative governance approach. Stronger public‐private partnerships would accelerate research, development, commercialization, and application of eDNA analysis to the benefit of society. Lessons form the early application of eDNA to detect invasive bigheaded carps in the Chicago Area Waterway System are relevant to accelerating the application of eDNA to other policy needs. Collaborative governance models, including the private sector, are likely to increase the societal benefits of eDNA for natural resource management.

Because significant global changes are currently underway in the Arctic, creating a large‐scale standardized database for Arctic marine biodiversity is particularly pressing. This study evaluates the potential of aquatic environmental DNA (eDNA) metabarcoding to detect Arctic coastal biodiversity changes and characterizes the local spatio‐temporal distribution of eDNA in two locations. We extracted and amplified eDNA using two COI primer pairs from ~80 water samples that were collected across two Canadian Arctic ports, Churchill and Iqaluit, based on optimized sampling and preservation methods for remote regions surveys. Results demonstrate that aquatic eDNA surveys have the potential to document large‐scale Arctic biodiversity change by providing a rapid overview of coastal metazoan biodiversity, detecting nonindigenous species, and allowing sampling in both open water and under the ice cover by local northern‐based communities. We show that DNA sequences of ~50% of known Canadian Arctic species and potential invaders are currently present in public databases. A similar proportion of operational taxonomic units was identified at the species level with eDNA metabarcoding, for a total of 181 species identified at both sites. Despite the cold and well‐mixed coastal environment, species composition was vertically heterogeneous, in part due to river inflow in the estuarine ecosystem, and differed between the water column and tide pools. Thus, COI‐based eDNA metabarcoding may quickly improve large‐scale Arctic biomonitoring using eDNA, but we caution that aquatic eDNA sampling needs to be standardized over space and time to accurately evaluate community structure changes. Despite the cold and well‐mixed coastal environment, eDNA composition was vertically heterogeneous, in part due to eDNA river inflow in the estuarine ecosystem, and differed between water column and tide pools. eDNA metabarcoding may quickly improve large‐scale Arctic biomonitoring, but we caution that water eDNA biomonitoring needs to be standardized over space and time to accurately evaluate community structure changes.

Environmental DNA (eDNA) metabarcoding can greatly enhance our understanding of global biodiversity and our ability to detect rare or cryptic species. However, sampling effort must be considered when interpreting results from these surveys. We explored how sampling effort influenced biodiversity patterns and nonindigenous species (NIS) detection in an eDNA metabarcoding survey of four commercial ports. Overall, we captured sequences from 18 metazoan phyla with minimal differences in taxonomic coverage between 18 S and COI primer sets. While community dissimilarity patterns were consistent across primers and sampling effort, richness patterns were not, suggesting that richness estimates are extremely sensitive to primer choice and sampling effort. The survey detected 64 potential NIS, with COI identifying more known NIS from port checklists but 18 S identifying more operational taxonomic units shared between three or more ports that represent un-recorded potential NIS. Overall, we conclude that eDNA metabarcoding surveys can reveal global similarity patterns among ports across a broad array of taxa and can also detect potential NIS in these key habitats. However, richness estimates and species assignments require caution. Based on results of this study, we make several recommendations for port eDNA sampling design and suggest several areas for future research.

International commerce in live organisms presents a policy challenge for trade globalization; sales of live organisms create wealth, but some nonindigenous species cause harm. To reduce damage, some countries have implemented species screening to limit the introduction of damaging species. Adoption of new risk assessment (RA) technologies has been slowed, however, by concerns that RA accuracy remains insufficient to produce positive net economic benefits. This concern arises because only a small proportion of all introduced species escape, spread, and cause harm (i.e., become invasive), so a RA will exclude many noninvasive species (which provide a net economic benefit) for every invasive species correctly identified. Here, we develop a simple cost:benefit bioeconomic framework to quantify the net benefits from applying species prescreening. Because invasive species are rarely eradicated, and their damages must therefore be borne for long periods, we have projected the value of RA over a suitable range of policy time horizons (10-500 years). We apply the model to the Australian plant quarantine program and show that this RA program produces positive net economic benefits over the range of reasonable assumptions. Because we use low estimates of the financial damage caused by invasive species and high estimates of the value of species in the ornamental trade, our results underestimate the net benefit of the Australian plant quarantine program. In addition, because plants have relatively low rates of invasion, applying screening protocols to animals would likely demonstrate even greater benefits.

We report results of a study that made reciprocal comparisons of environmental DNA (eDNA) assays for two major invasive crayfishes between their disparate invasive ranges in North America. Specifically, we tested for range expansions of the signal crayfish Pacifastacus leniusculus (Dana, 1852) into the Laurentian Great Lakes region known to be invaded by the rusty crayfish Orconectes rusticus (Girard, 1852), as well as for the invasion of O. rusticus into large lakes of California and Nevada, US known to be invaded by P. leniusculus. We compared eDNA detections to historic localities for O. rusticus within the Great Lakes, and to recent sampling for presence/absence and relative abundance of P. leniusculus in California and Nevada via overnight sets of baited traps. We successfully detected O. rusticus eDNA at six sites from the Great Lakes and P. leniusculus from six of seven lakes where it was known to occur in California and Nevada, but did not detect any range expansions by either species across the North American continent. eDNA appears suitable to detect benthic arthropods from exceptionally large lakes, and will likely be useful in applications for monitoring of new biological invasions into these and other freshwater and marine habitats.

Early detection is invaluable for the cost‐effective control and eradication of invasive species, yet many traditional sampling techniques are ineffective at the low population abundances found at the onset of the invasion process. Environmental DNA (eDNA) is a promising and sensitive tool for early detection of some invasive species, but its efficacy has not yet been evaluated for many taxonomic groups and habitat types. We evaluated the ability of eDNA to detect the invasive rusty crayfish Orconectes rusticus and to reflect patterns of its relative abundance, in upper Midwest, USA, inland lakes. We paired conventional baited trapping as a measure of crayfish relative abundance with water samples for eDNA, which were analysed in the laboratory with a qPCR assay. We modelled detection probability for O. rusticus eDNA using relative abundance and site characteristics as covariates and also tested the relationship between eDNA copy number and O. rusticus relative abundance. We detected O. rusticus eDNA in all lakes where this species was collected by trapping, down to low relative abundances, as well as in two lakes where trap catch was zero. Detection probability of O. rusticus eDNA was well predicted by relative abundance of this species and lake water clarity. However, there was poor correspondence between eDNA copy number and O. rusticus relative abundance estimated by trap catches. Synthesis and applications. Our study demonstrates a field and laboratory protocol for eDNA monitoring of crayfish invasions, with results of statistical models that provide guidance of sampling effort and detection probabilities for researchers in other regions and systems. We propose eDNA be included as a tool in surveillance for invasive or imperilled crayfishes and other benthic arthropods.