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Exotic species introductions are a major threat to biodiversity. The first step to their control involves identifying their presence, distribution, and impacts on native species and their habitats, especially in highly diverse regions. We update and document new records of exotic freshwater fauna from the Baja California Mediterranean region. We found 157 locality records of 17 exotic aquatic species; 16 genera and 15 families were recorded. Five species are new records for the region: Malaysian trumpet snail (Melanoides tuberculata), black bullhead catfish (Ameiurus melas), common carp (Cyprinus carpio), spiny softshell turtle (Apalone spinifera), and red-eared slider (Trachemys scripta). The catfish, carp, and softshell turtle have been previously reported from Baja California, but only from the Colorado River and adjacent Mexicali Valley, while the snail and slider represent new state records. Of the 157 locality records, 71 were found in published literature and 86 represent new records from field observations, collected specimens and citizen science observations. Based on discussions with local ranchers and landowners, some exotic species were introduced for food or aesthetic purposes, emphasizing the need for environmental programs to stop these actions. [ABSTRACT FROM AUTHOR]

Mathematical biology is a wide field of study with many venues that undergraduate students can access through research. However, the topics of study for these students can be overwhelming, and many topics of study yield either only trivial results or abstract outcomes that are nonintuitive and difficult to understand. We have used natural resource modeling, and more specifically, a partnership between academic researchers and federal scientists, as a bridge between undergraduate research and mathematical biology. Our collaboration is an interdisciplinary team that combines biology, mathematics, and statistics professors with government research scientists. As a team, we have mentored students through opportunities such as a Research Experiences for Undergraduates and other projects. In this article, we provide an overview of how we develop questions for undergraduates and outline two case studies, both of which resulted in peer reviewed journal articles. Last, we describe how we also transfer the results from these undergraduate projects to resource managers so the results may be applied to real world problems. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) has been approved by the US Environmental Protection Agency as a new aquatic pesticide to control invasive Asian carps and other aquatic nuisance species in the United States. However, limited CO2 toxicity data could make it challenging for resource managers to characterize the potential risk to nontarget species during CO2 applications. The present study quantified the toxicity of CO2 to 2 native riverine fishes, bluegill (Lepomis macrochirus) and fathead minnow (Pimephales promelas), using 12‐h continuous flow‐through CO2 exposure at 5, 15, and 25 °C water temperatures. Resulting survival indicated that bluegill (median lethal concentration [LC50] range 91–140 mg/L CO2) were more sensitive to CO2 than fathead minnow (LC50 range 235–306 mg/L CO2) across all water temperatures. Bluegill were also more sensitive to CO2 at 5 °C (LC50 91 mg/L CO2, 95% CI 85–96 mg/L CO2) than at 25 °C (LC50 140 mg/L CO2, 95% CI 135–146 mg/L CO2). Fathead minnow showed an opposite response and were less sensitive at 5 °C (LC50 306 mg/L CO2, 95% CI 286–327 mg/L CO2) relative to 25 °C (LC50 235 mg/L CO2, 95% CI 224–246 mg/L CO2). Our results show that CO2 toxicity can differ by species and water temperature. Data from the present study may inform decisions related to the use of CO2 as a control tool. Environ Toxicol Chem 2020;39:2247–2255. Published 2020. This article is a U.S. government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Zebra mussels (Dreissena polymorpha) have exacerbated the decline of native freshwater mussels (order Unionida) in North America since their arrival in the 1980s. Options for controlling invasive mussels, particularly in unionid mussel habitats, are limited. Previously, carbon dioxide (CO2) showed selective toxicity for zebra mussels, relative to unionids, when applied in cool water (12 °C). We first determined 96‐h lethal concentrations of CO2 at 5 and 20 °C to zebra mussels and responses of juvenile plain pocketbook (Lampsilis cardium). Next, we compared the time to lethality for zebra mussels at 5, 12, and 20 °C during exposure to partial pressure of CO2 (PCO2) values of 110 to 120 atm (1 atm = 101.325 kPa) and responses of juvenile plain pocketbook and fragile papershell (Leptodea fragilis). We found efficacious CO2 treatment regimens at each temperature that were minimally lethal to unionids. At 5 °C, plain pocketbook survived 96‐h exposure to the highest PCO2 treatment (139 atm). At 20 °C, the 96‐h lethal concentration to 10% of animals (LC10) for plain pocketbook (173 atm PCO2, 95% CI 147–198 atm) was higher than the LC99 for zebra mussels (118 atm PCO2, 95% CI 109–127 atm). Lethal time to 99% mortality (LT99) of zebra mussels in 110 to 120 atm PCO2 ranged from 100 h at 20 °C to 300 h at 5 °C. Mean survival of both plain pocketbook and fragile papershell juveniles exceeded 85% in LT99 CO2 treatments at all temperatures. Short‐term infusion of 100 to 200 atm PCO2 at a range of water temperatures could reduce biofouling by zebra mussels with limited adverse effects on unionid mussels. Environ Toxicol Chem 2020;39:1546–1557. Published 2020. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Effective natural resources management requires accurate information about species distributions. Environmental DNA (eDNA) analysis is a commonly used method to determine species presence and distribution. However, when understanding eDNA‐based distribution data, managers must contend with imperfect detection in collection samples and subsamples (i.e., molecular analyses) impacting their ability to detect species and estimate occurrence. Occurrence models can estimate 3 probabilities: occurrence, capture, and eDNA detection. However, most occurrence models do not. To quantify imperfect detection in rare versus common species, we examined multiple field capture and detection probabilities. We studied this with 3 objectives: Determine sample sizes required to detect eDNA given imperfect detection, determine sample sizes required to estimate eDNA capture parameters, and examine performance of a 3‐level occurrence model. We found detecting eDNA in ≥1 sample at a site required ≤15 samples per site for common species, but detecting eDNA when looking for rare species required 45 to 90 samples per site. Our occurrence model recovered known parameters unless capture and detection probabilities were <0.2 where >100 samples per site and ≥8 molecular replicates were required. Our findings illustrate the importance of sample size and molecular replication for eDNA‐based work. Integr Environ Assess Manag 2019;15:760–771. Published 2019. This article is a US Government work and is in the public domain in the USA. Key Points: Environmental DNA (eDNA) hold the potential to revolutionize sampling and monitoring programs by allowing passive sampling of biological organisms.Despite this promise, uncertainty exists about how to best design eDNA‐based studies.Our research examined how to design eDNA‐based sampling method.We found that 75 to 100 samples per site may be necessary to detect cryptic, rare, or otherwise difficult to detect species. [ABSTRACT FROM AUTHOR]

Understanding and conserving migratory species requires a method for characterizing the seasonal flow of animals among habitats. Source-sink theory describes the metapopulation dynamics of species by classifying habitats as population sources (i.e. net contributors) or sinks (i.e. net substractors). Migratory species may have non-breeding habitats important to the species (e.g. overwintering or stopover habitats) that traditional source-sink theory would classify as sinks because these habitats produce no individuals. Conversely, existing migratory network models can evaluate the relative contribution of non-breeding nodes, but these models make an equilibrium assumption that is difficult to meet when examining real migratory populations., We extend a pathway-based metric allowing breeding habitats, non-breeding habitats and migratory pathways connecting these habitats to be classified as sources or sinks. Rather than being based on whether place- or season-specific births exceed deaths, our approach quantifies the total demographic contribution from a node or migratory pathway over a flexibly defined yet limited time period across an organism's life cycle. As such, it provides a snapshot of a migratory system and therefore does not require assumptions associated with equilibrium dynamics., We first develop a generalizable mathematical notation and then demonstrate how the metric may be used with two case studies: the common loon ( Gavia immer) and Yellowstone cutthroat trout ( Oncorhynchus clarkii bouvieri). These examples highlight how stressors can impact stopover and wintering habitats (loons) and habitat management targeting migratory pathways can improve population status (trout)., Synthesis and applications. Each of the two case studies presented describes how effects at one location are felt by populations in another through the seasonal flow of individuals. The contribution metric we present should be helpful in allocating regulatory and management attention to times and locations most critical to migratory species persistence. [ABSTRACT FROM AUTHOR]

Invasive fish species disrupt ecosystems and cause economic damage. Several methods have been discussed to control populations of invasive fish including the release of YY-males. YY-males are fish that have 2 male chromosomes compared to a XY-male. When YY-males mate, they only produce male (XY) offspring. This decreases the female proportion of the population and can, in theory, eradicate local populations by biasing the sex-ratio. YY-males have been used as a population control tool for brook trout in montane streams and lakes in Idaho, USA. The YY-male control method has been discussed for grass carp in Lake Erie, North America. We developed and presented an integral projection model for grass carp to model the use of YY-males as a control method for populations in this lake. Using only the YY-male control method, we found that high levels of YY-males would need to be release annually to control the species. Specifically, these levels were the same order of magnitude as the baseline adult population (e.g., 1000 YY-males needed to be released annual for 20 years to control a baseline adult population of 2500 grass carp). These levels may not be reasonable or obtainable for fisheries managers given the impacts of YY-males on aquatic vegetation and other constraints of natural resource management. [ABSTRACT FROM AUTHOR]

Bigheaded carps, which include silver and bighead carp, are threatening to invade the Great Lakes. These species vary seasonally in distribution and abundance due to environmental conditions such as precipitation and temperature. Monitoring this seasonal movement is important for management to control the population size and spread of the species. We examined if environmental DNA (eDNA) approaches could detect seasonal changes of these species. To do this, we developed a novel genetic marker that was able to both detect and differentiate bighead and silver carp DNA. We used the marker, combined with a novel occupancy model, to study the occurrence of bigheaded carps at 3 sites on the Wabash River over the course of a year. We studied the Wabash River because of concerns that carps may be able to use the system to invade the Great Lakes via a now closed (ca. 2017) connection at Eagle Marsh between the Wabash River's watershed and the Great Lakes' watershed. We found seasonal trends in the probability of detection and occupancy that varied across sites. These findings demonstrate that eDNA methods can detect seasonal changes in bigheaded carps densities and suggest that the amount of eDNA present changes seasonally. The site that was farthest upstream and had the lowest carp densities exhibited the strongest seasonal trends for both detection probabilities and sample occupancy probabilities. Furthermore, other observations suggest that carps seasonally leave this site, and we were able to detect this with our eDNA approach. [ABSTRACT FROM AUTHOR]

Climate matching allows comparisons of climatic conditions between different locations to understand location and species range climatic suitability. The approach may be used as part of horizon scanning exercises such as those conducted for invasive species. We implemented the CLIMATCH algorithm into an R package, climatchR. The package allows automated and scripted climate matching exercises across all steps from downloading data to summarizing species climate matches. We also show how climatchR may be used with high-throughput computing to process many species. For example, we were able to calculate climate scores for over 8,000 species in less than 3 days using this package. This automation allows high-throughput processing of species data, a new development for improving the efficiency and speed of climate matching and horizon scanning. • climatchR allows for scripted and high-throughput climate matching with the R language. • climatchR works with a wide range of taxa including birds, mammals, fishes, reptiles, and amphibians. • The package may be used to identify potential areas for new species invasion (e.g., how well does the climate in a species established range match possible target ranges?). • climatchR readily integrates with high-throughput computing methods, specifically HTCondor. [ABSTRACT FROM AUTHOR]

Aedes albopictus has been the fastest spreading invasive animal species in the world from the mid-1980s until the mid-2000s. In areas it infests, it disrupts native mosquito ecology and can potentially vector up to 21 viruses. To better understand the population dynamics of this species, we created a temperature dependent population model. A stage-structured model was chosen to allow each life-stage to have different temperature dependent mortality and development rates, and each stage was modeled with an ordinary differential equation. Model parameters and distributions were based upon literature values. Initially, a basic model was constructed. This model then had parameters that were forced based upon daily average temperatures. Several criteria were used to evaluate the model, including a comparison to field data from Lubbock, TX. In a stochastic version of the model, a 95% confidence limit contained 70.7% of the field data points. Based upon these results, we feel reasonably confident that we have captured the role of temperature in driving the population dynamics of Ae. albopictus. [Copyright &y& Elsevier]

Conservation biology often requires the control of invasive species. One method is the development and use of biocides. Identifying new chemicals as part of the biocide registration approval process can require screening millions of compounds. Traditionally, screening new chemicals has been done in vivo using test organisms. Using in vitro (e.g., cell lines) and in silico (e.g., computer models) methods decrease test organism requirements and increase screening speed and efficiency. These methods, however, would be greatly improved by better understanding how individual fish species metabolize selected compounds. We combined cell assays and metabolomics to create a powerful tool to facilitate the identification of new control chemicals. Specifically, we exposed cell lines established from bighead carp and silver carp larvae to thiram (7 concentrations) then completed metabolite profiling to assess the dose-response of the bighead carp and silver carp metabolome to thiram. Forty one of the 700 metabolomic markers identified in bighead carp exhibited a dose-response to thiram exposure compared to silver carp in which 205 of 1590 metabolomic markers exhibited a dose-response. Additionally, we identified 11 statistically significant metabolomic markers based upon volcano plot analysis common between both species. This smaller subset of metabolites formed a thiram-specific metabolomic fingerprint which allowed for the creation of a toxicant specific, rather than a species-specific, metabolomic fingerprint. Metabolomic fingerprints may be used in biocide development and improve our understanding of ecologically significant events, such as mass fish kills. [ABSTRACT FROM AUTHOR]