Calibrating eDNA for Species Richness will require more populated reference databases, increased ... more Calibrating eDNA for Species Richness will require more populated reference databases, increased sampling effort, and multi-marker assays to ensure robust species richness estimates to further validate the approach. eDNA metabarcoding is reliable and provides a path for broader biodiversity assessments that can outperform conventional methods for estimating species richness.
Aim Impacts of non-native species have motivated development of risk assessment tools for identif... more Aim Impacts of non-native species have motivated development of risk assessment tools for identifying introduced species likely to become invasive. Here, we develop trait-based models for the establishment and impact stages of freshwater fish invasion, and use them to screen non-native species common in international trade. We also determine which species in the aquarium, biological supply, live bait, live food and water garden trades are likely to become invasive. Results are compared to historical patterns of non-native fish establishment to assess the relative importance over time of pathways in causing invasions. Location Laurentian Great Lakes region. Methods Trait-based classification trees for the establishment and impact stages of invasion were developed from data on freshwater fish species that established or failed to establish in the Great Lakes. Fishes in trade were determined from import data from Canadian and United States regulatory agencies, assigned to specific trades and screened through the developed models. Results Climate match between a species' native range and the Great Lakes region predicted establishment success with 75-81% accuracy. Trophic guild and fecundity predicted potential harmful impacts of established non-native fishes with 75-83% accuracy. Screening outcomes suggest the water garden trade poses the greatest risk of introducing new invasive species, followed by the live food and aquarium trades. Analysis of historical patterns of introduction pathways demonstrates the increasing importance of these trades relative to other pathways. Comparisons among trades reveal that model predictions parallel historical patterns; all fishes previously introduced from the water garden trade have established. The live bait, biological supply, aquarium and live food trades have also contributed established non-native fishes. Main conclusions Our models predict invasion risk of potential fish invaders to the Great Lakes region and could help managers prioritize efforts among species and pathways to minimize such risk. Similar approaches could be applied to other taxonomic groups and geographic regions.
Biodiversity surveys may require the use of multiple types of sampling gear to maximize the effic... more Biodiversity surveys may require the use of multiple types of sampling gear to maximize the efficiency of species detections, yet few studies have investigated how to optimally distribute effort among gear. In this study, we conducted eDNA metabarcoding and capture‐based sampling surveys (electrofishing, fyke netting, gillnetting, and seining) to sample fish species richness in a large northern temperate lake. We evaluated the success of the sampling methods individually and in combination to determine the allocation of effort and cost across sampling gear that provides the optimal approach for lake‐wide species inventories. We found that eDNA metabarcoding detected more species than any other sampling method, including 11 species that were not detected with any capture‐based approach. Optimal gear combination analyses revealed that detected species richness is maximized when most of the effort or budget is allocated to eDNA metabarcoding, with smaller allocations to seining and fyk...
North American Journal of Fisheries Management, 2021
Bigheaded carps (BHCs; Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis) are e... more Bigheaded carps (BHCs; Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis) are economically and culturally important in Asia and Europe but are considered highly invasive throughout the Mississippi River watershed and pose a threat to the food web and fisheries of the Laurentian Great Lakes. We used the Ecopath with Ecosim model framework to evaluate potential risk of BHC population growth and food web effects in four Great Lakes habitats, including mesotrophic waters of Saginaw Bay (Lake Huron) and Lake Erie and the oligotrophic main basins of Lakes Michigan and Huron. We simulated BHC population growth and food web effects under different scenarios of BHC production rates, prey vulnerability to BHCs, and availability of age‐0 BHCs to predation by salmonines. In the main basins of Lakes Michigan and Huron, the projected BHC population growth was low or negative, with a projected final BHC biomass of 0.5–1.1 times the initial introductory biomass (2% of total fish b...
Effective engagement among scientists, government agency staff, and policymakers is necessary for... more Effective engagement among scientists, government agency staff, and policymakers is necessary for solving fisheries challenges, but remains challenging for a variety of reasons. We present seven practices learned from a collaborative project focused on invasive species in the Great Lakes region (USA‐CAN). These practices were based on a researcher–manager model composed of a research team, a management advisory board, and a bridging organization. We suggest this type of system functions well when (1) the management advisory board is provided compelling rationale for engagement; (2) the process uses key individuals as communicators; (3) the research team thoughtfully selects organizations and individuals involved; (4) the funding entity provides logistical support and allows for (5) a flexible structure that prioritizes management needs; (6) a bridging organization sustains communication between in‐person meetings; and (7) the project team determines and enacts a project endpoint. We...
ABSTRACT Background/Question/Methods Understanding how environmental variables at multiple scales... more ABSTRACT Background/Question/Methods Understanding how environmental variables at multiple scales influence the structure of stream fish assemblages is important for habitat assessment, stream restoration, and for predicting responses to environmental change. A focus on the functional structure of species assemblages in relation to environmental gradients may reveal more general patterns applicable across geographic regions. In this study, we used functional traits related to the trophic ecology, habitat use, and life-history strategies of fishes to examine the influences of environmental factors on stream fish assemblages in the Brazos and Trinity river basins in Central Texas. Relationships between functional structure of assemblages and environmental factors at local, landscape, and regional scales were examined. We also identified associations between functional diversity of fish assemblages and established measures of biotic integrity and habitat quality. Results/Conclusions Environmental characteristics at all three scales influenced the functional attributes of assemblages studied here. At the local reach scale, stream size, substrate characteristics, the availability of riffle and pool habitats, and abundance of in-stream cover structures were related to the functional trait composition of fish assemblages. Landscape features most strongly related to functional structure were the extent of forested area in the watershed and the amount of land developed for urban and agricultural uses. At the regional scale, broad physiographic differences between ecoregions had a large influence on the taxonomic and functional composition of stream fish assemblages in Central Texas. In general, the functional trait-space occupied by fish assemblages was greatest in streams with high habitat quality scores located within landscapes with less alteration for agriculture and urban development. Currently used indices of biotic integrity incorporate some functional aspects of fish assemblage structure (e.g., trophic guilds, pollution tolerance categories), but identifying specific functional traits or suites of traits related to stream habitat quality could potentially improve on these approaches and provide more sensitive and broadly applicable metrics.
We report results of a study that made reciprocal comparisons of environmental DNA (eDNA) assays ... more 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.
The spread of nonindigenous species by shipping is a large and growing global problem that harms ... more The spread of nonindigenous species by shipping is a large and growing global problem that harms coastal ecosystems and economies and may blur coastal biogeographical patterns. This study coupled eukaryotic environmental DNA (eDNA) metabarcoding with dissimilarity regression to test the hypothesis that ship‐borne species spread homogenizes port communities. We first collected and metabarcoded water samples from ports in Europe, Asia, Australia and the Americas. We then calculated community dissimilarities between port pairs and tested for effects of environmental dissimilarity, biogeographical region and four alternative measures of ship‐borne species transport risk. We predicted that higher shipping between ports would decrease community dissimilarity, that the effect of shipping would be small compared to that of environment dissimilarity and shared biogeography, and that more complex shipping risk metrics (which account for ballast water and stepping‐stone spread) would perform b...
Synthesis research in ecology and environmental science improves understanding, advances theory, ... more Synthesis research in ecology and environmental science improves understanding, advances theory, identifies research priorities, and supports management strategies by linking data, ideas, and tools. Accelerating environmental challenges increases the need to focus synthesis science on the most pressing questions. To leverage input from the broader research community, we convened a virtual workshop with participants from many countries and disciplines to examine how and where synthesis can address key questions and themes in ecology and environmental science in the coming decade. Seven priority research topics emerged: (1) diversity, equity, inclusion, and justice (DEIJ), (2) human and natural systems, (3) actionable and use‐inspired science, (4) scale, (5) generality, (6) complexity and resilience, and (7) predictability. Additionally, two issues regarding the general practice of synthesis emerged: the need for increased participant diversity and inclusive research practices; and in...
Invasive nonindigenous species are defined by their impacts: they substantially change native com... more Invasive nonindigenous species are defined by their impacts: they substantially change native communities or ecosystems. Accordingly, invasive species might transform their habitats in ways that eventually become unfavorable to them, causing population declines or even extirpations. Here we use over 40 yr of systematically collected data on the abundance of the invasive rusty crayfish Faxonius rusticus from 17 lakes in northern Wisconsin, USA to explore whether population declines of this invader are related to the prevalence of rocky habitat, which shelters crayfish from predators and is unchanged by crayfish. We predicted that lakes with rock‐dominated substrates would be resistant to F. rusticus population declines, whereas lakes lacking rock‐dominated substrates would experience F. rusticus declines due to crayfish destruction of shelter‐providing macrophytes. We found that in nearly one‐half (47%) of the study lakes, F. rusticus experienced population declines over the study ti...
Knowledge of aquatic invasive species (AIS) dispersal is important to inform surveillance and man... more Knowledge of aquatic invasive species (AIS) dispersal is important to inform surveillance and management efforts to slow the spread of established invaders. We studied potential dispersal of invasive Eurasian ruffe Gymnocephalus cernua and golden mussel Limnoperna fortunei larvae in Lakes Michigan and Erie using a threedimensional particle transport model. Ruffe is currently in Lake Superior and northern Lake Michigan, while Limnoperna has not yet invaded the Great Lakes. We predicted larval transport during several spawning seasons (individual years) from several major tributaries and ports that are most prone to invasion because of their significant recreational and commercial usage. Depending on release location, larvae traveled distances ranging from b1 km to tens of kilometers (in some cases over 100-200 km, depending on species) during 2-3 weeks of drift time. Dispersal distances from nearshore locations (i.e. rivers and ports) were smaller than from offshore deballasting locations near ports. Limnoperna dispersal distances were larger than ruffe due to stronger seasonal currents and longer drift period. Settlement areas resulting from offshore releases were larger than for nearshore releases, and larger for Limnoperna than for ruffe. Model results compared favorably to observed spread of ruffe and Dreissena spp. mussels in Lake Michigan. Our modeling effort suggests that larval advection by lake currents is an important AIS dispersal mechanism in the Great Lakes. It also emphasizes the importance of effective surveillance programs that maximize early detection of new introductions before lake current dispersal obviates containment and prevention of spread and impacts.
February 1999, President Clinton mandated the development of an Invasive Species Management Plan ... more February 1999, President Clinton mandated the development of an Invasive Species Management Plan for the United States, emphasizing in Executive Order 13112 the severity of the economic, human health, and ecological threats posed by nonindigenous species (NIS). The plan must review the anthropogenic vectors that move species, and recommend measures to minimize future introductions. Elsewhere in this issue, we have reviewed the special threats to freshwater biodiversity and ecosystem function posed by nonindigenous crayfishes (from within North America and from other continents), and identified the vectors potentially most important in introducing crayfishes: aquaculture; aquarium and pond trade; biological supply trade; and the live bait trade. In this essay, we outline recommendations for reducing future crayfish introductions in the United States by these vectors, and call for the development of methods to eradicate or control nonindigenous crayfishes. We hope that these recommendations will be considered during the development of the Invasive Species Management Plan. While we believe our recommendations may apply to many freshwater animal and plant taxa, we focus on crayfishes in this essay for the following reasons. First, the United States encompasses about 350 species of crayfishes, 70% of the world’s total. Second, these crayfishes are among the most threatened of all terrestrial and aquatic species in the United States. Finally, although U.S. crayfishes are severely threatened, there remains a window of opportunity to implement policies that could prevent the extinction of many native crayfishes and prevent the large ecosystem changes that often accompany introductions of nonindigenous crayfishes. Our hope is to avoid the ecological and economic disasters that befell the fisheries for European crayfishes after the introduction of nonindigenous crayfishes there. In Europe and North America, nonindigenous crayfishes have often eliminated native crayfishes from lakes and streams, eliminated aquatic vegetation where it is important fish and macroinvertebrate habitat, reduced abundance of insect larvae and other invertebrates used by fishes, and reduced abundance of native amphibians. Nonindigenous crayfishes have had additional devastating impacts on the commercial fishery for native European crayfishes, which have much greater market value than the introduced species. European harvests of crayfish for human consumption are now only about 5% of their historic levels; many European countries have implemented
Journal of the North American Benthological Society, 1993
... D. Grant Allen, and Jan K. Spelt Chapter 17 Influence of Chemical Composition of the Water on... more ... D. Grant Allen, and Jan K. Spelt Chapter 17 Influence of Chemical Composition of the Water on the Mollusk Dreissena polymorpha ... de Kock and CT Bowmer SECTION IV Mitigation Chapter 31 Monitoring and Control of Dreissena polymorpha and Other Macrofouling Bivalves in ...
In a series of three experiments, greenhouse-grown bush bean plants (Phaseolus vulgaris L. cv 'Bl... more In a series of three experiments, greenhouse-grown bush bean plants (Phaseolus vulgaris L. cv 'Blue Lake 274') were exposed to simulated rain (200 ml, 40 min) at pH 5.6, 4.0, or 3.2 2--4 times per week during weeks 3-7 of growth. Solutions ofidentical chemistry and volume were added to the soil of another set of plants. The threshold for visible injury and significant growth reduction due to rain exposures was between pH 4.0 and 3.2. More unifoliate leaves of plants exposed to pH 4.0 or 3.2 sulfuric acid rain were senescent at harvest than those exposed to pH 5.6 rain (control treatment). However, the trifoliate leaves of the same plants often had greater leaf chlorophyll concentrations, thus apparently compensating for the observed premature senescence of unifoliate leaves. There was no significant effect of acidity on the plant growth parameters when solutions were applied only to the soil. Therefore, the effects of rain acidity in these experiments were probably direct foliar effects, rather than indirect effects mediated by effects on the soil media. Comparison of growth differences between plants exposed to rain at a constant pH 3.2 level and those exposed to rain that increased in pH from 2.8 to 4.0 with a pH 3.2 mean indicated a tendency for rain events with a high peak level of acidity to cause greater deleterious effects on bean plants than those rain events characterized by a constant pH level.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
... Science, Vol.270, No.5236, 561-561, 1995 EndNote로 서지반출하기. The Role of Experiments in Ecology.... more ... Science, Vol.270, No.5236, 561-561, 1995 EndNote로 서지반출하기. The Role of Experiments in Ecology. Power ME, Tilman D, Carpenter SR, Huntly N, Leibold M, Morin P, Menge BA, Estes JA, Ehrlich PR, Hixon M, Lodge DM, Mcpeek MA, Fauth JE, Reznick D, Crowder LB ...
Calibrating eDNA for Species Richness will require more populated reference databases, increased ... more Calibrating eDNA for Species Richness will require more populated reference databases, increased sampling effort, and multi-marker assays to ensure robust species richness estimates to further validate the approach. eDNA metabarcoding is reliable and provides a path for broader biodiversity assessments that can outperform conventional methods for estimating species richness.
Aim Impacts of non-native species have motivated development of risk assessment tools for identif... more Aim Impacts of non-native species have motivated development of risk assessment tools for identifying introduced species likely to become invasive. Here, we develop trait-based models for the establishment and impact stages of freshwater fish invasion, and use them to screen non-native species common in international trade. We also determine which species in the aquarium, biological supply, live bait, live food and water garden trades are likely to become invasive. Results are compared to historical patterns of non-native fish establishment to assess the relative importance over time of pathways in causing invasions. Location Laurentian Great Lakes region. Methods Trait-based classification trees for the establishment and impact stages of invasion were developed from data on freshwater fish species that established or failed to establish in the Great Lakes. Fishes in trade were determined from import data from Canadian and United States regulatory agencies, assigned to specific trades and screened through the developed models. Results Climate match between a species' native range and the Great Lakes region predicted establishment success with 75-81% accuracy. Trophic guild and fecundity predicted potential harmful impacts of established non-native fishes with 75-83% accuracy. Screening outcomes suggest the water garden trade poses the greatest risk of introducing new invasive species, followed by the live food and aquarium trades. Analysis of historical patterns of introduction pathways demonstrates the increasing importance of these trades relative to other pathways. Comparisons among trades reveal that model predictions parallel historical patterns; all fishes previously introduced from the water garden trade have established. The live bait, biological supply, aquarium and live food trades have also contributed established non-native fishes. Main conclusions Our models predict invasion risk of potential fish invaders to the Great Lakes region and could help managers prioritize efforts among species and pathways to minimize such risk. Similar approaches could be applied to other taxonomic groups and geographic regions.
Biodiversity surveys may require the use of multiple types of sampling gear to maximize the effic... more Biodiversity surveys may require the use of multiple types of sampling gear to maximize the efficiency of species detections, yet few studies have investigated how to optimally distribute effort among gear. In this study, we conducted eDNA metabarcoding and capture‐based sampling surveys (electrofishing, fyke netting, gillnetting, and seining) to sample fish species richness in a large northern temperate lake. We evaluated the success of the sampling methods individually and in combination to determine the allocation of effort and cost across sampling gear that provides the optimal approach for lake‐wide species inventories. We found that eDNA metabarcoding detected more species than any other sampling method, including 11 species that were not detected with any capture‐based approach. Optimal gear combination analyses revealed that detected species richness is maximized when most of the effort or budget is allocated to eDNA metabarcoding, with smaller allocations to seining and fyk...
North American Journal of Fisheries Management, 2021
Bigheaded carps (BHCs; Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis) are e... more Bigheaded carps (BHCs; Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis) are economically and culturally important in Asia and Europe but are considered highly invasive throughout the Mississippi River watershed and pose a threat to the food web and fisheries of the Laurentian Great Lakes. We used the Ecopath with Ecosim model framework to evaluate potential risk of BHC population growth and food web effects in four Great Lakes habitats, including mesotrophic waters of Saginaw Bay (Lake Huron) and Lake Erie and the oligotrophic main basins of Lakes Michigan and Huron. We simulated BHC population growth and food web effects under different scenarios of BHC production rates, prey vulnerability to BHCs, and availability of age‐0 BHCs to predation by salmonines. In the main basins of Lakes Michigan and Huron, the projected BHC population growth was low or negative, with a projected final BHC biomass of 0.5–1.1 times the initial introductory biomass (2% of total fish b...
Effective engagement among scientists, government agency staff, and policymakers is necessary for... more Effective engagement among scientists, government agency staff, and policymakers is necessary for solving fisheries challenges, but remains challenging for a variety of reasons. We present seven practices learned from a collaborative project focused on invasive species in the Great Lakes region (USA‐CAN). These practices were based on a researcher–manager model composed of a research team, a management advisory board, and a bridging organization. We suggest this type of system functions well when (1) the management advisory board is provided compelling rationale for engagement; (2) the process uses key individuals as communicators; (3) the research team thoughtfully selects organizations and individuals involved; (4) the funding entity provides logistical support and allows for (5) a flexible structure that prioritizes management needs; (6) a bridging organization sustains communication between in‐person meetings; and (7) the project team determines and enacts a project endpoint. We...
ABSTRACT Background/Question/Methods Understanding how environmental variables at multiple scales... more ABSTRACT Background/Question/Methods Understanding how environmental variables at multiple scales influence the structure of stream fish assemblages is important for habitat assessment, stream restoration, and for predicting responses to environmental change. A focus on the functional structure of species assemblages in relation to environmental gradients may reveal more general patterns applicable across geographic regions. In this study, we used functional traits related to the trophic ecology, habitat use, and life-history strategies of fishes to examine the influences of environmental factors on stream fish assemblages in the Brazos and Trinity river basins in Central Texas. Relationships between functional structure of assemblages and environmental factors at local, landscape, and regional scales were examined. We also identified associations between functional diversity of fish assemblages and established measures of biotic integrity and habitat quality. Results/Conclusions Environmental characteristics at all three scales influenced the functional attributes of assemblages studied here. At the local reach scale, stream size, substrate characteristics, the availability of riffle and pool habitats, and abundance of in-stream cover structures were related to the functional trait composition of fish assemblages. Landscape features most strongly related to functional structure were the extent of forested area in the watershed and the amount of land developed for urban and agricultural uses. At the regional scale, broad physiographic differences between ecoregions had a large influence on the taxonomic and functional composition of stream fish assemblages in Central Texas. In general, the functional trait-space occupied by fish assemblages was greatest in streams with high habitat quality scores located within landscapes with less alteration for agriculture and urban development. Currently used indices of biotic integrity incorporate some functional aspects of fish assemblage structure (e.g., trophic guilds, pollution tolerance categories), but identifying specific functional traits or suites of traits related to stream habitat quality could potentially improve on these approaches and provide more sensitive and broadly applicable metrics.
We report results of a study that made reciprocal comparisons of environmental DNA (eDNA) assays ... more 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.
The spread of nonindigenous species by shipping is a large and growing global problem that harms ... more The spread of nonindigenous species by shipping is a large and growing global problem that harms coastal ecosystems and economies and may blur coastal biogeographical patterns. This study coupled eukaryotic environmental DNA (eDNA) metabarcoding with dissimilarity regression to test the hypothesis that ship‐borne species spread homogenizes port communities. We first collected and metabarcoded water samples from ports in Europe, Asia, Australia and the Americas. We then calculated community dissimilarities between port pairs and tested for effects of environmental dissimilarity, biogeographical region and four alternative measures of ship‐borne species transport risk. We predicted that higher shipping between ports would decrease community dissimilarity, that the effect of shipping would be small compared to that of environment dissimilarity and shared biogeography, and that more complex shipping risk metrics (which account for ballast water and stepping‐stone spread) would perform b...
Synthesis research in ecology and environmental science improves understanding, advances theory, ... more Synthesis research in ecology and environmental science improves understanding, advances theory, identifies research priorities, and supports management strategies by linking data, ideas, and tools. Accelerating environmental challenges increases the need to focus synthesis science on the most pressing questions. To leverage input from the broader research community, we convened a virtual workshop with participants from many countries and disciplines to examine how and where synthesis can address key questions and themes in ecology and environmental science in the coming decade. Seven priority research topics emerged: (1) diversity, equity, inclusion, and justice (DEIJ), (2) human and natural systems, (3) actionable and use‐inspired science, (4) scale, (5) generality, (6) complexity and resilience, and (7) predictability. Additionally, two issues regarding the general practice of synthesis emerged: the need for increased participant diversity and inclusive research practices; and in...
Invasive nonindigenous species are defined by their impacts: they substantially change native com... more Invasive nonindigenous species are defined by their impacts: they substantially change native communities or ecosystems. Accordingly, invasive species might transform their habitats in ways that eventually become unfavorable to them, causing population declines or even extirpations. Here we use over 40 yr of systematically collected data on the abundance of the invasive rusty crayfish Faxonius rusticus from 17 lakes in northern Wisconsin, USA to explore whether population declines of this invader are related to the prevalence of rocky habitat, which shelters crayfish from predators and is unchanged by crayfish. We predicted that lakes with rock‐dominated substrates would be resistant to F. rusticus population declines, whereas lakes lacking rock‐dominated substrates would experience F. rusticus declines due to crayfish destruction of shelter‐providing macrophytes. We found that in nearly one‐half (47%) of the study lakes, F. rusticus experienced population declines over the study ti...
Knowledge of aquatic invasive species (AIS) dispersal is important to inform surveillance and man... more Knowledge of aquatic invasive species (AIS) dispersal is important to inform surveillance and management efforts to slow the spread of established invaders. We studied potential dispersal of invasive Eurasian ruffe Gymnocephalus cernua and golden mussel Limnoperna fortunei larvae in Lakes Michigan and Erie using a threedimensional particle transport model. Ruffe is currently in Lake Superior and northern Lake Michigan, while Limnoperna has not yet invaded the Great Lakes. We predicted larval transport during several spawning seasons (individual years) from several major tributaries and ports that are most prone to invasion because of their significant recreational and commercial usage. Depending on release location, larvae traveled distances ranging from b1 km to tens of kilometers (in some cases over 100-200 km, depending on species) during 2-3 weeks of drift time. Dispersal distances from nearshore locations (i.e. rivers and ports) were smaller than from offshore deballasting locations near ports. Limnoperna dispersal distances were larger than ruffe due to stronger seasonal currents and longer drift period. Settlement areas resulting from offshore releases were larger than for nearshore releases, and larger for Limnoperna than for ruffe. Model results compared favorably to observed spread of ruffe and Dreissena spp. mussels in Lake Michigan. Our modeling effort suggests that larval advection by lake currents is an important AIS dispersal mechanism in the Great Lakes. It also emphasizes the importance of effective surveillance programs that maximize early detection of new introductions before lake current dispersal obviates containment and prevention of spread and impacts.
February 1999, President Clinton mandated the development of an Invasive Species Management Plan ... more February 1999, President Clinton mandated the development of an Invasive Species Management Plan for the United States, emphasizing in Executive Order 13112 the severity of the economic, human health, and ecological threats posed by nonindigenous species (NIS). The plan must review the anthropogenic vectors that move species, and recommend measures to minimize future introductions. Elsewhere in this issue, we have reviewed the special threats to freshwater biodiversity and ecosystem function posed by nonindigenous crayfishes (from within North America and from other continents), and identified the vectors potentially most important in introducing crayfishes: aquaculture; aquarium and pond trade; biological supply trade; and the live bait trade. In this essay, we outline recommendations for reducing future crayfish introductions in the United States by these vectors, and call for the development of methods to eradicate or control nonindigenous crayfishes. We hope that these recommendations will be considered during the development of the Invasive Species Management Plan. While we believe our recommendations may apply to many freshwater animal and plant taxa, we focus on crayfishes in this essay for the following reasons. First, the United States encompasses about 350 species of crayfishes, 70% of the world’s total. Second, these crayfishes are among the most threatened of all terrestrial and aquatic species in the United States. Finally, although U.S. crayfishes are severely threatened, there remains a window of opportunity to implement policies that could prevent the extinction of many native crayfishes and prevent the large ecosystem changes that often accompany introductions of nonindigenous crayfishes. Our hope is to avoid the ecological and economic disasters that befell the fisheries for European crayfishes after the introduction of nonindigenous crayfishes there. In Europe and North America, nonindigenous crayfishes have often eliminated native crayfishes from lakes and streams, eliminated aquatic vegetation where it is important fish and macroinvertebrate habitat, reduced abundance of insect larvae and other invertebrates used by fishes, and reduced abundance of native amphibians. Nonindigenous crayfishes have had additional devastating impacts on the commercial fishery for native European crayfishes, which have much greater market value than the introduced species. European harvests of crayfish for human consumption are now only about 5% of their historic levels; many European countries have implemented
Journal of the North American Benthological Society, 1993
... D. Grant Allen, and Jan K. Spelt Chapter 17 Influence of Chemical Composition of the Water on... more ... D. Grant Allen, and Jan K. Spelt Chapter 17 Influence of Chemical Composition of the Water on the Mollusk Dreissena polymorpha ... de Kock and CT Bowmer SECTION IV Mitigation Chapter 31 Monitoring and Control of Dreissena polymorpha and Other Macrofouling Bivalves in ...
In a series of three experiments, greenhouse-grown bush bean plants (Phaseolus vulgaris L. cv 'Bl... more In a series of three experiments, greenhouse-grown bush bean plants (Phaseolus vulgaris L. cv 'Blue Lake 274') were exposed to simulated rain (200 ml, 40 min) at pH 5.6, 4.0, or 3.2 2--4 times per week during weeks 3-7 of growth. Solutions ofidentical chemistry and volume were added to the soil of another set of plants. The threshold for visible injury and significant growth reduction due to rain exposures was between pH 4.0 and 3.2. More unifoliate leaves of plants exposed to pH 4.0 or 3.2 sulfuric acid rain were senescent at harvest than those exposed to pH 5.6 rain (control treatment). However, the trifoliate leaves of the same plants often had greater leaf chlorophyll concentrations, thus apparently compensating for the observed premature senescence of unifoliate leaves. There was no significant effect of acidity on the plant growth parameters when solutions were applied only to the soil. Therefore, the effects of rain acidity in these experiments were probably direct foliar effects, rather than indirect effects mediated by effects on the soil media. Comparison of growth differences between plants exposed to rain at a constant pH 3.2 level and those exposed to rain that increased in pH from 2.8 to 4.0 with a pH 3.2 mean indicated a tendency for rain events with a high peak level of acidity to cause greater deleterious effects on bean plants than those rain events characterized by a constant pH level.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
... Science, Vol.270, No.5236, 561-561, 1995 EndNote로 서지반출하기. The Role of Experiments in Ecology.... more ... Science, Vol.270, No.5236, 561-561, 1995 EndNote로 서지반출하기. The Role of Experiments in Ecology. Power ME, Tilman D, Carpenter SR, Huntly N, Leibold M, Morin P, Menge BA, Estes JA, Ehrlich PR, Hixon M, Lodge DM, Mcpeek MA, Fauth JE, Reznick D, Crowder LB ...
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