Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. A... more Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. As invasion rates accelerate worldwide, understanding past invasion dynamics is essential to inform predictions of future invaders and impacts. Owing to a high diversity of pathways and current biosecurity gaps, aquatic systems near urban centres are especially susceptible to alien species establishments. Here, we compiled and compared alien species lists for three different aquatic recipient regions spanning the North Atlantic: Chesapeake Bay, Great Lakes‐St. Lawrence River and North and Baltic Seas. Each system is a major trade centre, with a history of invasions, and characterized by a strong natural salinity gradient. Our goal was to compare the alien species across systems, to test for similarities in the taxonomic composition and geographic origin as well as species overlap among the three regions. We selected specific macroinvertebrate, algal and fish taxa for analysis, to control ...
Aim For over 80 years, the Maine baitworm trade has shipped live polychaete worms and packing alg... more Aim For over 80 years, the Maine baitworm trade has shipped live polychaete worms and packing algae 'wormweed' to distributors worldwide , while also consistently transferring a wide diversity and abundance of hitchhiking organisms of all life stages to numerous recipient communities. Here, we investigate this potent, yet underestimated, invasion vector using an important recipient region (the Mid-Atlantic) to examine the stepwise species transfer and survival along four stages of the vector.
During the nineteenth century the mud snail Ilyanassa obsoleta was abundant on sand and mud flats... more During the nineteenth century the mud snail Ilyanassa obsoleta was abundant on sand and mud flats, wood works, sea walls, salt marshes, eel grass beds, and cobble beaches in New England. With the exception of sand and mud flats, these habitats arenow largely occupied bytheintroduced periwinkle, Littorina littorea. To determine whether Littorina competitively displaces Ilyanassa, an experimental study wascon ducted at a site in Barnstable Harbor, Massachusetts where the observed distributions overlapped by 3% by Monsita's index. Mark-recapture studies suggested that the distribution of Littorina was limited by an abiotic factor, currents, through which this species realized its fundamental niche. In contrast, density manipulations demonstrated that Ilyanassa emigrated from areas where Littorina exceeded densities of 2 to 5 per 0.25 m2. Littorina limited the upper and lower distribution of Ilyanassa and affected its microhabitat distribution in the mid intertidal zone. Habitat displacement was 70% for Ilyanassa, calculated as the difference between Ilyanassa's observed distribution and its distribution during littorinid removal experiments. The two species display reciprocal niche overlap with each possessing an exclusive region from which the other is physically restricted. The results suggest that the historical change in the distribution of Ilyanassa was due to competitive exclusion by introduced Littorina.
A single CSV file containing descriptions of Japanese tsunami debris objects (object type, date i... more A single CSV file containing descriptions of Japanese tsunami debris objects (object type, date intercepted, location found, size) and the unique taxa found on each. Please see the README.txt for detailed descriptions of each column.
We present here a simple general framework for vector science, modified, expanded and updated fro... more We present here a simple general framework for vector science, modified, expanded and updated from earlier discussions a decade ago in Carlton and Ruiz (2005). Vector science encompasses the phenomena involved in the passive movement of species by human activities and the resulting propagule pressure, as well as the number of invasions related to a given vector over time. Vector science thus captures portions of four of the stages in classic invasion models: transport, introduction, establishment and spread (Blackburn et al., 2011; Lockwood et al., 2013). Numerous papers have summarized and classified the many vectors by which human activity moves marine and estuarine biota (including viruses, bacteria, protists, fungi, animals, and plants) within and between oceans (Carlton & Scanlon, 1985;
We show that the high seas are colonized by a diverse array of coastal species, which survive and... more We show that the high seas are colonized by a diverse array of coastal species, which survive and reproduce in the open ocean, contributing strongly to its floating community composition. Analysis of rafting plastic debris in the eastern North Pacific Subtropical Gyre revealed 37 coastal invertebrate taxa, largely of Western Pacific origin, exceeding pelagic taxa richness by threefold. Coastal taxa, including diverse taxonomic groups and life history traits, occurred on 70.5% of debris items. Most coastal taxa possessed either direct development or asexual reproduction, possibly facilitating long-term persistence on rafts. Our results suggest that the historical lack of available substrate limited the colonization of the open ocean by coastal species, rather than physiological or ecological constraints as previously assumed. It appears that coastal species persist now in the open ocean as a substantial component of a neopelagic community sustained by the vast and expanding sea of pl...
In discussing the vital importance of taxonomic expertise for managing biological invasions, we n... more In discussing the vital importance of taxonomic expertise for managing biological invasions, we noted that difficulties in recognizing cryptic species can challenge the use of classical biological control. As an example, we described control efforts targeting Adelges tsugae, the hemlock woolly adelgid, during which collections from Japan of the intended biocontrol insect Laricobius osakensis were inadvertently contaminated with individuals of its cryptic congener L. naganoensis. Specifically, we wrote (p. 130) "The U.S. Department of Agriculture subsequently permitted further introduction of L. naganoensis, requiring no risk assessment or monitoring, simply because it was too difficult to distinguish it readily from its congener". We should have specified that the U.S. Department of Agriculture, citing the difficulty of distinguishing between the two species, approved release of L. naganoensis based on the opinion that it was unlikely to establish and, if it did, it would probably not have a harmful impact (USDA 2017). Furthermore, we wish to clarify that despite government approval L. naganoensis was never released into eastern North America. Reference USDA. 2017. Amended finding of no significant impact for field release of Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), a predatory beetle for biological control of Hemlock Woolly Adelgid, Adelges tsugae (Hemiptera: Adelgidae), in the continental United States, December 2017. Plant Protection and Quarantine, Animal and
The Massachusetts Office of Coastal Zone Management (CZM) would like to acknowledge the exception... more The Massachusetts Office of Coastal Zone Management (CZM) would like to acknowledge the exceptional work of the 2010 Rapid Assessment Survey (RAS) team for their tireless efforts to collect and analyze marine invasive species data and for providing logistical support for the survey:
Widespread non-native species tend to demonstrate an apparent lack of selectivity in habitat requ... more Widespread non-native species tend to demonstrate an apparent lack of selectivity in habitat requirements, feeding regimes, and reproductive needs, while displaying a tendency to thrive in human-modified habitats. The high phenotypic plasticity typical of sessile, substrate-attached marine species may enhance their chances of survival and spread in a new region. Anthropogenic activities have changed marine habitats over a wide range of phenomena, including water temperature, community species composition, and the types of available substrates, creating new physical and biotic regimes that may contribute to the potential for successful species introduction. Here we examine ten species of sea anemones that have been introduced outside of their native range, and elucidate specific characteristics that are common among globally introduced sea anemones. Various life history strategies enable these species to survive and flourish through transport, introduction, establishment and spread, leading to the successful colonization of a new geographic area. Considering life history strategies and weighing of vector potential, we suggest conditions that facilitate introduction of these species, and identify species of sea anemones that may be introduced in the future in the face of changing climate and increased anthropogenic activities.
ABSTRACTBiological invasions are a global consequence of an increasingly connected world and the ... more ABSTRACTBiological invasions are a global consequence of an increasingly connected world and the rise in human population size. The numbers of invasive alien species – the subset of alien species that spread widely in areas where they are not native, affecting the environment or human livelihoods – are increasing. Synergies with other global changes are exacerbating current invasions and facilitating new ones, thereby escalating the extent and impacts of invaders. Invasions have complex and often immense long‐term direct and indirect impacts. In many cases, such impacts become apparent or problematic only when invaders are well established and have large ranges. Invasive alien species break down biogeographic realms, affect native species richness and abundance, increase the risk of native species extinction, affect the genetic composition of native populations, change native animal behaviour, alter phylogenetic diversity across communities, and modify trophic networks. Many invasiv...
Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. A... more Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. As invasion rates accelerate worldwide, understanding past invasion dynamics is essential to inform predictions of future invaders and impacts. Owing to a high diversity of pathways and current biosecurity gaps, aquatic systems near urban centres are especially susceptible to alien species establishments. Here, we compiled and compared alien species lists for three different aquatic recipient regions spanning the North Atlantic: Chesapeake Bay, Great Lakes‐St. Lawrence River and North and Baltic Seas. Each system is a major trade centre, with a history of invasions, and characterized by a strong natural salinity gradient. Our goal was to compare the alien species across systems, to test for similarities in the taxonomic composition and geographic origin as well as species overlap among the three regions. We selected specific macroinvertebrate, algal and fish taxa for analysis, to control ...
Aim For over 80 years, the Maine baitworm trade has shipped live polychaete worms and packing alg... more Aim For over 80 years, the Maine baitworm trade has shipped live polychaete worms and packing algae 'wormweed' to distributors worldwide , while also consistently transferring a wide diversity and abundance of hitchhiking organisms of all life stages to numerous recipient communities. Here, we investigate this potent, yet underestimated, invasion vector using an important recipient region (the Mid-Atlantic) to examine the stepwise species transfer and survival along four stages of the vector.
During the nineteenth century the mud snail Ilyanassa obsoleta was abundant on sand and mud flats... more During the nineteenth century the mud snail Ilyanassa obsoleta was abundant on sand and mud flats, wood works, sea walls, salt marshes, eel grass beds, and cobble beaches in New England. With the exception of sand and mud flats, these habitats arenow largely occupied bytheintroduced periwinkle, Littorina littorea. To determine whether Littorina competitively displaces Ilyanassa, an experimental study wascon ducted at a site in Barnstable Harbor, Massachusetts where the observed distributions overlapped by 3% by Monsita's index. Mark-recapture studies suggested that the distribution of Littorina was limited by an abiotic factor, currents, through which this species realized its fundamental niche. In contrast, density manipulations demonstrated that Ilyanassa emigrated from areas where Littorina exceeded densities of 2 to 5 per 0.25 m2. Littorina limited the upper and lower distribution of Ilyanassa and affected its microhabitat distribution in the mid intertidal zone. Habitat displacement was 70% for Ilyanassa, calculated as the difference between Ilyanassa's observed distribution and its distribution during littorinid removal experiments. The two species display reciprocal niche overlap with each possessing an exclusive region from which the other is physically restricted. The results suggest that the historical change in the distribution of Ilyanassa was due to competitive exclusion by introduced Littorina.
A single CSV file containing descriptions of Japanese tsunami debris objects (object type, date i... more A single CSV file containing descriptions of Japanese tsunami debris objects (object type, date intercepted, location found, size) and the unique taxa found on each. Please see the README.txt for detailed descriptions of each column.
We present here a simple general framework for vector science, modified, expanded and updated fro... more We present here a simple general framework for vector science, modified, expanded and updated from earlier discussions a decade ago in Carlton and Ruiz (2005). Vector science encompasses the phenomena involved in the passive movement of species by human activities and the resulting propagule pressure, as well as the number of invasions related to a given vector over time. Vector science thus captures portions of four of the stages in classic invasion models: transport, introduction, establishment and spread (Blackburn et al., 2011; Lockwood et al., 2013). Numerous papers have summarized and classified the many vectors by which human activity moves marine and estuarine biota (including viruses, bacteria, protists, fungi, animals, and plants) within and between oceans (Carlton & Scanlon, 1985;
We show that the high seas are colonized by a diverse array of coastal species, which survive and... more We show that the high seas are colonized by a diverse array of coastal species, which survive and reproduce in the open ocean, contributing strongly to its floating community composition. Analysis of rafting plastic debris in the eastern North Pacific Subtropical Gyre revealed 37 coastal invertebrate taxa, largely of Western Pacific origin, exceeding pelagic taxa richness by threefold. Coastal taxa, including diverse taxonomic groups and life history traits, occurred on 70.5% of debris items. Most coastal taxa possessed either direct development or asexual reproduction, possibly facilitating long-term persistence on rafts. Our results suggest that the historical lack of available substrate limited the colonization of the open ocean by coastal species, rather than physiological or ecological constraints as previously assumed. It appears that coastal species persist now in the open ocean as a substantial component of a neopelagic community sustained by the vast and expanding sea of pl...
In discussing the vital importance of taxonomic expertise for managing biological invasions, we n... more In discussing the vital importance of taxonomic expertise for managing biological invasions, we noted that difficulties in recognizing cryptic species can challenge the use of classical biological control. As an example, we described control efforts targeting Adelges tsugae, the hemlock woolly adelgid, during which collections from Japan of the intended biocontrol insect Laricobius osakensis were inadvertently contaminated with individuals of its cryptic congener L. naganoensis. Specifically, we wrote (p. 130) "The U.S. Department of Agriculture subsequently permitted further introduction of L. naganoensis, requiring no risk assessment or monitoring, simply because it was too difficult to distinguish it readily from its congener". We should have specified that the U.S. Department of Agriculture, citing the difficulty of distinguishing between the two species, approved release of L. naganoensis based on the opinion that it was unlikely to establish and, if it did, it would probably not have a harmful impact (USDA 2017). Furthermore, we wish to clarify that despite government approval L. naganoensis was never released into eastern North America. Reference USDA. 2017. Amended finding of no significant impact for field release of Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), a predatory beetle for biological control of Hemlock Woolly Adelgid, Adelges tsugae (Hemiptera: Adelgidae), in the continental United States, December 2017. Plant Protection and Quarantine, Animal and
The Massachusetts Office of Coastal Zone Management (CZM) would like to acknowledge the exception... more The Massachusetts Office of Coastal Zone Management (CZM) would like to acknowledge the exceptional work of the 2010 Rapid Assessment Survey (RAS) team for their tireless efforts to collect and analyze marine invasive species data and for providing logistical support for the survey:
Widespread non-native species tend to demonstrate an apparent lack of selectivity in habitat requ... more Widespread non-native species tend to demonstrate an apparent lack of selectivity in habitat requirements, feeding regimes, and reproductive needs, while displaying a tendency to thrive in human-modified habitats. The high phenotypic plasticity typical of sessile, substrate-attached marine species may enhance their chances of survival and spread in a new region. Anthropogenic activities have changed marine habitats over a wide range of phenomena, including water temperature, community species composition, and the types of available substrates, creating new physical and biotic regimes that may contribute to the potential for successful species introduction. Here we examine ten species of sea anemones that have been introduced outside of their native range, and elucidate specific characteristics that are common among globally introduced sea anemones. Various life history strategies enable these species to survive and flourish through transport, introduction, establishment and spread, leading to the successful colonization of a new geographic area. Considering life history strategies and weighing of vector potential, we suggest conditions that facilitate introduction of these species, and identify species of sea anemones that may be introduced in the future in the face of changing climate and increased anthropogenic activities.
ABSTRACTBiological invasions are a global consequence of an increasingly connected world and the ... more ABSTRACTBiological invasions are a global consequence of an increasingly connected world and the rise in human population size. The numbers of invasive alien species – the subset of alien species that spread widely in areas where they are not native, affecting the environment or human livelihoods – are increasing. Synergies with other global changes are exacerbating current invasions and facilitating new ones, thereby escalating the extent and impacts of invaders. Invasions have complex and often immense long‐term direct and indirect impacts. In many cases, such impacts become apparent or problematic only when invaders are well established and have large ranges. Invasive alien species break down biogeographic realms, affect native species richness and abundance, increase the risk of native species extinction, affect the genetic composition of native populations, change native animal behaviour, alter phylogenetic diversity across communities, and modify trophic networks. Many invasiv...
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Papers by James Carlton