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• 1. [Article] Classifying Oregon lake-watershed ecosystems for regional water resources assessment

  Natural lake-watershed ecosystems in Oregon compose a diverse and valuable assemblage of land and water resources. With an increasing demand on lakes for recreation, water supplies, and aesthetic values ...

  Citation × Citation Citation Abstract Copy Title: Classifying Oregon lake-watershed ecosystems for regional water resources assessment Author: Jones, Randall Alan Year: 1987 Natural lake-watershed ecosystems in Oregon compose a diverse and valuable assemblage of land and water resources. With an increasing demand on lakes for recreation, water supplies, and aesthetic values and an increase in available data on Oregon lake systems, there is a need for applicable and timely scientific water management information about lake conditions statewide. This thesis is an attempt to summarize some of the data collected on natural Oregon lake-watershed ecosystems. The purpose of the thesis is to identify the most typical natural systems out of an initial data base of twenty-four variables, measured over ninety-eight lake-watershed ecosystems. The selected variables are reduced to five common factors using principal components factor analysis. K-means cluster analysis is used to create similar groups of lake systems. These groups are compared to ecoregions in Oregon and a typical, representative lake ecosystem is identified for each group. Results show that several lake systems of the state are unique. Title: Classifying Oregon lake-watershed ecosystems for regional water resources assessment Author: Jones, Randall Alan Year: 1987 Natural lake-watershed ecosystems in Oregon compose a diverse and valuable assemblage of land and water resources. With an increasing demand on lakes for recreation, water supplies, and aesthetic values and an increase in available data on Oregon lake systems, there is a need for applicable and timely scientific water management information about lake conditions statewide. This thesis is an attempt to summarize some of the data collected on natural Oregon lake-watershed ecosystems. The purpose of the thesis is to identify the most typical natural systems out of an initial data base of twenty-four variables, measured over ninety-eight lake-watershed ecosystems. The selected variables are reduced to five common factors using principal components factor analysis. K-means cluster analysis is used to create similar groups of lake systems. These groups are compared to ecoregions in Oregon and a typical, representative lake ecosystem is identified for each group. Results show that several lake systems of the state are unique. Close

• 2. [Article] Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective

  Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ...

  Citation × Citation Citation Abstract Copy Title: Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective Author: Janssen, Annette B.G., Arhonditsis, George B., Beusen, Arthur, Bolding, Karsten, Bruce, Louise, Bruggeman, Jorn, Couture, Raoul-Marie, Downing, Andrea S., Elliott, J. Alex, Frassl, Marieke A., Gal, Gideon, Gerla, Daan J., Hipsey, Matthew R., Hu, Fenjuan, Ives, Stephen C., Janse, Jan H., Jeppesen, Erik, Jöhnk, Klaus D., Kneis, David, Kong, Xiangzhen, Kuiper, Jan J., Lehmann, Moritz K., Lemmen, Carsten, Özkundakci, Deniz, Petzoldt, Thomas, Rinke, Karsten, Robson, Barbara J., Sachse, René, Schep, Sebastiaan A., Schmid, Martin, Scholten, Huub, Teurlincx, Sven, Trolle, Dennis, Troost, Tineke A., Van Dam, Anne A., Van Gerven, Luuk P.A., Weijerman, Mariska, Wells, Scott A., Mooij, Wolf M. Year: 2015 Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary. Title: Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective Author: Janssen, Annette B.G., Arhonditsis, George B., Beusen, Arthur, Bolding, Karsten, Bruce, Louise, Bruggeman, Jorn, Couture, Raoul-Marie, Downing, Andrea S., Elliott, J. Alex, Frassl, Marieke A., Gal, Gideon, Gerla, Daan J., Hipsey, Matthew R., Hu, Fenjuan, Ives, Stephen C., Janse, Jan H., Jeppesen, Erik, Jöhnk, Klaus D., Kneis, David, Kong, Xiangzhen, Kuiper, Jan J., Lehmann, Moritz K., Lemmen, Carsten, Özkundakci, Deniz, Petzoldt, Thomas, Rinke, Karsten, Robson, Barbara J., Sachse, René, Schep, Sebastiaan A., Schmid, Martin, Scholten, Huub, Teurlincx, Sven, Trolle, Dennis, Troost, Tineke A., Van Dam, Anne A., Van Gerven, Luuk P.A., Weijerman, Mariska, Wells, Scott A., Mooij, Wolf M. Year: 2015 Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary. Close

• 3. [Article] Northern Range Expansion and Coastal Occurrences of the New Zealand Mud Snail Potamopyrgus Antipodarum (Gray, 1843) in the Northeast Pacific

  The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is a common invasive species in fresh and brackish water ecosystems in Europe, Australia, Japan, and North America. In some invaded habitats, ...

  Citation × Citation Citation Abstract Copy Title: Northern Range Expansion and Coastal Occurrences of the New Zealand Mud Snail Potamopyrgus Antipodarum (Gray, 1843) in the Northeast Pacific Author: Davidson, Timothy Mathias, Brenneis, Valance E. F., de Rivera, Catherine E., Draheim, Robyn, Gillespie, Graham E. Year: 2008 The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is a common invasive species in fresh and brackish water ecosystems in Europe, Australia, Japan, and North America. In some invaded habitats, P. antipodarum can reach high densities (over 500,000 snails m-2) and dominate the biomass of the benthos, leading to detrimental impacts to native biota and changes in ecosystem dynamics. We report the previously unpublished occurrence of P. antipodarum in thirteen fresh and brackish water systems adjacent to the Pacific coast of North America including a new northern range for P. antipodarum: Port Alberni, Vancouver Island, British Columbia, Canada (49.2479º, -124.8395º). We hypothesize the snail was spread from the Columbia River Estuary to Port Alberni via recreational watercraft or infected fishing equipment. Its discovery in Port Alberni reveals the potential for other aquatic nuisance species in the lower Columbia River to spread to British Columbia. Resource managers on the Pacific coast should remain vigilant and educate the public to prevent the further spread of the P. antipodarum as well as other aquatic invaders. Title: Northern Range Expansion and Coastal Occurrences of the New Zealand Mud Snail Potamopyrgus Antipodarum (Gray, 1843) in the Northeast Pacific Author: Davidson, Timothy Mathias, Brenneis, Valance E. F., de Rivera, Catherine E., Draheim, Robyn, Gillespie, Graham E. Year: 2008 The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is a common invasive species in fresh and brackish water ecosystems in Europe, Australia, Japan, and North America. In some invaded habitats, P. antipodarum can reach high densities (over 500,000 snails m-2) and dominate the biomass of the benthos, leading to detrimental impacts to native biota and changes in ecosystem dynamics. We report the previously unpublished occurrence of P. antipodarum in thirteen fresh and brackish water systems adjacent to the Pacific coast of North America including a new northern range for P. antipodarum: Port Alberni, Vancouver Island, British Columbia, Canada (49.2479º, -124.8395º). We hypothesize the snail was spread from the Columbia River Estuary to Port Alberni via recreational watercraft or infected fishing equipment. Its discovery in Port Alberni reveals the potential for other aquatic nuisance species in the lower Columbia River to spread to British Columbia. Resource managers on the Pacific coast should remain vigilant and educate the public to prevent the further spread of the P. antipodarum as well as other aquatic invaders. Close

• 4. [Article] Invasive Predator, Bythotrephes, has Varied Effects on Ecosystem Function in Freshwater Lakes

  Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes ...

  Citation × Citation Citation Abstract Copy Title: Invasive Predator, Bythotrephes, has Varied Effects on Ecosystem Function in Freshwater Lakes Author: Strecker, Angela L., Arnott, Shelley E. Year: 2008 Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes on two measures of ecosystem function during a four month observational study of freshwater lakes on the boreal shield. Bythotrephes-invaded lakes had significantly lower epilimnetic zooplankton abundance and production compared to reference lakes. On average, Bythotrephes consumed 34% ofzooplankton production when it was present in lakes. There was some evidence of changes in the timing of zooplankton production, as well as shifts to cooler, less productive habitats, which may lessen the overall effect of the invader on the transfer of energy to higher trophic levels. We experimentally demonstrated a weak trophic cascade where invader predation reduced zooplankton biomass, and subsequently increased phytoplankton growth. However, the response was small in magnitude and not biologically relevant at the whole lake- scale. The most conspicuous effect of Bythotrephes that we measured was a diversion of energy away from native predators at higher trophic levels. Title: Invasive Predator, Bythotrephes, has Varied Effects on Ecosystem Function in Freshwater Lakes Author: Strecker, Angela L., Arnott, Shelley E. Year: 2008 Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes on two measures of ecosystem function during a four month observational study of freshwater lakes on the boreal shield. Bythotrephes-invaded lakes had significantly lower epilimnetic zooplankton abundance and production compared to reference lakes. On average, Bythotrephes consumed 34% ofzooplankton production when it was present in lakes. There was some evidence of changes in the timing of zooplankton production, as well as shifts to cooler, less productive habitats, which may lessen the overall effect of the invader on the transfer of energy to higher trophic levels. We experimentally demonstrated a weak trophic cascade where invader predation reduced zooplankton biomass, and subsequently increased phytoplankton growth. However, the response was small in magnitude and not biologically relevant at the whole lake- scale. The most conspicuous effect of Bythotrephes that we measured was a diversion of energy away from native predators at higher trophic levels. Close

• 5. [Article] Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis

  Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments ...

  Citation × Citation Citation Abstract Copy Title: Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis Author: Lewis, Casey Year: 2017 Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments of the species to inform appropriate management decisions. Red mangrove was introduced to Moloka'i, Hawaii in 1902 to mitigate the effects of soil erosion and has since spread along the coast and to adjacent islands creating novel habitat. This study assessed both biological services and social attitudes towards Moloka'i's non-native mangroves to provide a comprehensive evaluation of the species. Zooplankton community structure was examined in mangrove and non-mangrove sites and found to be different depending on the amount of mangroves present. Surveys of Moloka'i residents revealed no majority attitude towards mangroves nor support for complete eradication but residents were highly supportive of active management. Approaching other novel ecosystems created by established non-native species from a socio-ecological view may become more crucial as changes in climate, demographics, and environmental conditions further complicate effects. In our globalized world, non-native species introductions will continue to have both positive and negative effects that vary over time. Therefore, assessment of both social and ecological perspectives may lead to more effective management with greater community support. Title: Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis Author: Lewis, Casey Year: 2017 Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments of the species to inform appropriate management decisions. Red mangrove was introduced to Moloka'i, Hawaii in 1902 to mitigate the effects of soil erosion and has since spread along the coast and to adjacent islands creating novel habitat. This study assessed both biological services and social attitudes towards Moloka'i's non-native mangroves to provide a comprehensive evaluation of the species. Zooplankton community structure was examined in mangrove and non-mangrove sites and found to be different depending on the amount of mangroves present. Surveys of Moloka'i residents revealed no majority attitude towards mangroves nor support for complete eradication but residents were highly supportive of active management. Approaching other novel ecosystems created by established non-native species from a socio-ecological view may become more crucial as changes in climate, demographics, and environmental conditions further complicate effects. In our globalized world, non-native species introductions will continue to have both positive and negative effects that vary over time. Therefore, assessment of both social and ecological perspectives may lead to more effective management with greater community support. Close

• 6. [Article] The Response of Zooplankton Communities in Montane Lakes of Different Fish Stocking Histories to Atmospheric Nitrogen Deposition Simulations

  Freshwater ecosystems are subject to a wide variety of stressors, which can have complex interactions and result in ecological surprises. Non-native fish introductions have drastically reduced the number ...

  Citation × Citation Citation Abstract Copy Title: The Response of Zooplankton Communities in Montane Lakes of Different Fish Stocking Histories to Atmospheric Nitrogen Deposition Simulations Author: Brittain, Jeffrey Thomas Year: 2015 Freshwater ecosystems are subject to a wide variety of stressors, which can have complex interactions and result in ecological surprises. Non-native fish introductions have drastically reduced the number of naturally fishless lakes and have resulted in cascading food web repercussions in aquatic and terrestrial habitats. Additional anthropogenic influences that result from increases in global airborne emissions also threaten wildlife habitat. Atmospheric nitrogen deposition has been recognized as an anthropogenic contributor to acidification and eutrophication of wilderness ecosystems. Planktonic communities have shown declines in response to predation and shifts in composition as a result of nutrient inputs and acidification, both of which are potential fates of nitrogen deposition. This study identified the response of zooplankton communities from two lakes (fish present vs. absent) in Mount Rainier National Park to manipulations simulating an episodic disturbance event in mesocosms. The experiment used a 2 x 2 factorial design with acid and nitrogen treatments. Treatments resulted in significantly elevated nitrogen and decreased pH conditions from control mesocosms over 42 days, indicating that the treatment effects were achieved. Results indicate that zooplankton communities from lakes with different food web structure respond differently to the singular effects of acid and nitrogen addition. Surprisingly, the interaction of the two stressors was related to increases in community metrics (e.g., abundance, biomass, body size, richness, and Shannon-Weiner diversity) for both lake types. This work can aid management decisions as agencies look to restore more aquatic montane habitats to their historic fishless states, and assess their abilities to recover and afford resistance to atmospheric pollution. Title: The Response of Zooplankton Communities in Montane Lakes of Different Fish Stocking Histories to Atmospheric Nitrogen Deposition Simulations Author: Brittain, Jeffrey Thomas Year: 2015 Freshwater ecosystems are subject to a wide variety of stressors, which can have complex interactions and result in ecological surprises. Non-native fish introductions have drastically reduced the number of naturally fishless lakes and have resulted in cascading food web repercussions in aquatic and terrestrial habitats. Additional anthropogenic influences that result from increases in global airborne emissions also threaten wildlife habitat. Atmospheric nitrogen deposition has been recognized as an anthropogenic contributor to acidification and eutrophication of wilderness ecosystems. Planktonic communities have shown declines in response to predation and shifts in composition as a result of nutrient inputs and acidification, both of which are potential fates of nitrogen deposition. This study identified the response of zooplankton communities from two lakes (fish present vs. absent) in Mount Rainier National Park to manipulations simulating an episodic disturbance event in mesocosms. The experiment used a 2 x 2 factorial design with acid and nitrogen treatments. Treatments resulted in significantly elevated nitrogen and decreased pH conditions from control mesocosms over 42 days, indicating that the treatment effects were achieved. Results indicate that zooplankton communities from lakes with different food web structure respond differently to the singular effects of acid and nitrogen addition. Surprisingly, the interaction of the two stressors was related to increases in community metrics (e.g., abundance, biomass, body size, richness, and Shannon-Weiner diversity) for both lake types. This work can aid management decisions as agencies look to restore more aquatic montane habitats to their historic fishless states, and assess their abilities to recover and afford resistance to atmospheric pollution. Close

• 7. [Article] Rapid Change in Shallow Water Fish Species Composition in an Historically Stable Antarctic Environment

  McMurdo Sound, Antarctica, is home to a unique marine biota with an ecology that has evolved in this frigid environment over millions of years. The region is one of the least disturbed, and possibly the ...

  Citation × Citation Citation Abstract Copy Title: Rapid Change in Shallow Water Fish Species Composition in an Historically Stable Antarctic Environment Author: Buckley, Bradley A. Year: 2013 McMurdo Sound, Antarctica, is home to a unique marine biota with an ecology that has evolved in this frigid environment over millions of years. The region is one of the least disturbed, and possibly the last pristine, marine ecosystem on Earth. Here, the results of three seasons of fishing in the shallow nearshore waters of McMurdo Sound are reported. A shift in the composition of small fish species at one site, Inaccessible Island, has been observed in just five years. The shift in shallow water species composition occurred during a period that followed the maturation of a commercial fishery for the Antarctic toothfish, Dissostichus mawsoni Norman, a predator of smaller fish, and the presence of a large iceberg, termed B-15, at the mouth of McMurdo Sound during the early 2000s that trapped the annual sea ice in the area leading to the unusual accrual of multi-year sea ice. The data presented here provide a current record of species composition and physiological condition of small, shallow water fishes at three sites in McMurdo Sound, providing a current baseline for the assessment of future changes wrought by environmental changes and unprecedented fishery pressures in the Ross Sea. Title: Rapid Change in Shallow Water Fish Species Composition in an Historically Stable Antarctic Environment Author: Buckley, Bradley A. Year: 2013 McMurdo Sound, Antarctica, is home to a unique marine biota with an ecology that has evolved in this frigid environment over millions of years. The region is one of the least disturbed, and possibly the last pristine, marine ecosystem on Earth. Here, the results of three seasons of fishing in the shallow nearshore waters of McMurdo Sound are reported. A shift in the composition of small fish species at one site, Inaccessible Island, has been observed in just five years. The shift in shallow water species composition occurred during a period that followed the maturation of a commercial fishery for the Antarctic toothfish, Dissostichus mawsoni Norman, a predator of smaller fish, and the presence of a large iceberg, termed B-15, at the mouth of McMurdo Sound during the early 2000s that trapped the annual sea ice in the area leading to the unusual accrual of multi-year sea ice. The data presented here provide a current record of species composition and physiological condition of small, shallow water fishes at three sites in McMurdo Sound, providing a current baseline for the assessment of future changes wrought by environmental changes and unprecedented fishery pressures in the Ross Sea. Close

• 8. [Article] Greenhouse Gas Fluxes in Southeastern U.S. Coastal Plain Wetlands Under Contrasting Land Uses

  Whether through sea level rise or wetland restoration, agricultural soils in coastal areas will be inundated at increasing rates, renewing connections to sensitive surface waters and raising critical questions ...

  Citation × Citation Citation Abstract Copy Title: Greenhouse Gas Fluxes in Southeastern U.S. Coastal Plain Wetlands Under Contrasting Land Uses Author: Morse, Jennifer L., Ardón, Marcelo, Bernhardt, Emily S. Year: 2012 Whether through sea level rise or wetland restoration, agricultural soils in coastal areas will be inundated at increasing rates, renewing connections to sensitive surface waters and raising critical questions about environmental trade-offs. Wetland restoration is often implemented in agricultural catchments to improve water quality through nutrient removal. Yet flooding of soils can also increase production of the greenhouse gases nitrous oxide and methane, representing a potential environmental trade-off. Our study aimed to quantify and compare greenhouse gas emissions from unmanaged and restored forested wetlands, as well as actively managed agricultural fields within the North Carolina coastal plain, USA. In sampling conducted once every two months over a two-year comparative study, we found that soil carbon dioxide flux (range: 8000–64 800 kg CO2·ha-1· yr-1) comprised 66–100% of total greenhouse gas emissions from all sites and that methane emissions (range: -6.87 to 197 kg CH4·ha-1·yr-1) were highest from permanently inundated sites, while nitrous oxide fluxes (range: -1.07 to 139 kg N2O·ha-1·yr-1) were highest in sites with lower water tables. Contrary to predictions, greenhouse gas fluxes (as CO2 equivalents) from the restored wetland were lower than from either agricultural fields or unmanaged forested wetlands. In these acidic coastal freshwater ecosystems, the conversion of agricultural fields to flooded young forested wetlands did not result in increases in greenhouse gas emissions. Title: Greenhouse Gas Fluxes in Southeastern U.S. Coastal Plain Wetlands Under Contrasting Land Uses Author: Morse, Jennifer L., Ardón, Marcelo, Bernhardt, Emily S. Year: 2012 Whether through sea level rise or wetland restoration, agricultural soils in coastal areas will be inundated at increasing rates, renewing connections to sensitive surface waters and raising critical questions about environmental trade-offs. Wetland restoration is often implemented in agricultural catchments to improve water quality through nutrient removal. Yet flooding of soils can also increase production of the greenhouse gases nitrous oxide and methane, representing a potential environmental trade-off. Our study aimed to quantify and compare greenhouse gas emissions from unmanaged and restored forested wetlands, as well as actively managed agricultural fields within the North Carolina coastal plain, USA. In sampling conducted once every two months over a two-year comparative study, we found that soil carbon dioxide flux (range: 8000–64 800 kg CO2·ha-1· yr-1) comprised 66–100% of total greenhouse gas emissions from all sites and that methane emissions (range: -6.87 to 197 kg CH4·ha-1·yr-1) were highest from permanently inundated sites, while nitrous oxide fluxes (range: -1.07 to 139 kg N2O·ha-1·yr-1) were highest in sites with lower water tables. Contrary to predictions, greenhouse gas fluxes (as CO2 equivalents) from the restored wetland were lower than from either agricultural fields or unmanaged forested wetlands. In these acidic coastal freshwater ecosystems, the conversion of agricultural fields to flooded young forested wetlands did not result in increases in greenhouse gas emissions. Close

• 9. [Article] Biotic Resistance to Invasion: Native Predator Limits Abundance and Distribution of an Introduced Crab

  Introduced species frequently escape the natural enemies (predators, competitors, and parasites) that limit their distribution and abundance in the native range. This reduction in native predators, competitors, ...

  Citation × Citation Citation Abstract Copy Title: Biotic Resistance to Invasion: Native Predator Limits Abundance and Distribution of an Introduced Crab Author: de Rivera, Catherine E., Ruiz, Greg M., Hines, Anson, Jivoff, Paul Year: 2005 Introduced species frequently escape the natural enemies (predators, competitors, and parasites) that limit their distribution and abundance in the native range. This reduction in native predators, competitors, and parasites may result in ecological release in the introduced range. However, biological interactions also can limit the establishment and spread of nonnative populations. The extent to which such biotic resistance occurs is poorly resolved, especially for marine ecosystems. Here we test whether a native predator, the blue crab Callinectes sapidus, affects the abundance and geographic range of the introduced European green crab Carcinus maenas in eastern North America. Both crab species occur in shallow, soft-sediment habitats of bays and estuaries, and their ranges overlap in eastern North America. First, we tested for a negative relationship in the abundances of the two species from trap samples across a 640-km (5.78° latitude) coastal transect. Second, we estimated variation in predation pressure on tethered Carcinus maenas across latitude and as a function of Callinectes sapidus abundance. Third, we measured predation rates on Carcinus maenas by Callinectes sapidus in field and laboratory experiments. Our results support the hypothesis that the native predator Callinectes sapidus provides biotic resistance to invasion and prevents the southward spread and establishment of Carcinus maenas. Within and across bays, Carcinus maenas were significantly less abundant at sites and depths with Callinectes sapidus compared with areas lacking Callinectes sapidus. Moreover, no Carcinus maenas were found in Chesapeake Bay, where Callinectes sapidus were most abundant. Predation of tethered Carcinus maenas increased with Callinectes sapidus abundance. In laboratory and field experiments, Callinectes sapidus preyed readily on Carcinus maenas. Thus, we conclude the predation by Callinectes sapidus, alone or in combination with other factors, limits the abundance and geographic range of an invasive marine species. Title: Biotic Resistance to Invasion: Native Predator Limits Abundance and Distribution of an Introduced Crab Author: de Rivera, Catherine E., Ruiz, Greg M., Hines, Anson, Jivoff, Paul Year: 2005 Introduced species frequently escape the natural enemies (predators, competitors, and parasites) that limit their distribution and abundance in the native range. This reduction in native predators, competitors, and parasites may result in ecological release in the introduced range. However, biological interactions also can limit the establishment and spread of nonnative populations. The extent to which such biotic resistance occurs is poorly resolved, especially for marine ecosystems. Here we test whether a native predator, the blue crab Callinectes sapidus, affects the abundance and geographic range of the introduced European green crab Carcinus maenas in eastern North America. Both crab species occur in shallow, soft-sediment habitats of bays and estuaries, and their ranges overlap in eastern North America. First, we tested for a negative relationship in the abundances of the two species from trap samples across a 640-km (5.78° latitude) coastal transect. Second, we estimated variation in predation pressure on tethered Carcinus maenas across latitude and as a function of Callinectes sapidus abundance. Third, we measured predation rates on Carcinus maenas by Callinectes sapidus in field and laboratory experiments. Our results support the hypothesis that the native predator Callinectes sapidus provides biotic resistance to invasion and prevents the southward spread and establishment of Carcinus maenas. Within and across bays, Carcinus maenas were significantly less abundant at sites and depths with Callinectes sapidus compared with areas lacking Callinectes sapidus. Moreover, no Carcinus maenas were found in Chesapeake Bay, where Callinectes sapidus were most abundant. Predation of tethered Carcinus maenas increased with Callinectes sapidus abundance. In laboratory and field experiments, Callinectes sapidus preyed readily on Carcinus maenas. Thus, we conclude the predation by Callinectes sapidus, alone or in combination with other factors, limits the abundance and geographic range of an invasive marine species. Close

• 10. [Article] The Aquarium Trade as an Invasion Pathway in the Pacific Northwest

  The aquarium trade moves thousands of species around the globe, and unwanted organisms may be released into freshwaters, with adverse ecological and economic effects. We report on the first investigation ...

  Citation × Citation Citation Abstract Copy Title: The Aquarium Trade as an Invasion Pathway in the Pacific Northwest Author: Strecker, Angela L., Campbell, Philip M., Olden, Julian D. Year: 2011 The aquarium trade moves thousands of species around the globe, and unwanted organisms may be released into freshwaters, with adverse ecological and economic effects. We report on the first investigation of the ornamental pet trade as an invasion pathway in the Pacific Northwest region of the United States, where a moderate climate and a large human population present ample opportunities for the introduction and establishment of aquarium trade species. Results from a regional survey of pet stores found that the number of fish (n=400) and plant (n=124) species currently in the aquarium trade is vast. Pet stores import thousands of fish every month, the majority of which (58%) are considered to pose an ecological threat to native ecosystems. Our propagule pressure model suggests that approximately 2,500 fish (maximum 21,000 individuals) are likely released annually to the Puget Sound region by aquarists, and that water temperatures in many parts of Washington are suitable for establishment of populations. In conclusion, the aquarium trade may be a significant source of past and future invasions in the Pacific Northwest, and we recommend enhanced public education programs, greater regulation of the aquarium industry, and improved legislation of nonnative species in the ornamental trade. Title: The Aquarium Trade as an Invasion Pathway in the Pacific Northwest Author: Strecker, Angela L., Campbell, Philip M., Olden, Julian D. Year: 2011 The aquarium trade moves thousands of species around the globe, and unwanted organisms may be released into freshwaters, with adverse ecological and economic effects. We report on the first investigation of the ornamental pet trade as an invasion pathway in the Pacific Northwest region of the United States, where a moderate climate and a large human population present ample opportunities for the introduction and establishment of aquarium trade species. Results from a regional survey of pet stores found that the number of fish (n=400) and plant (n=124) species currently in the aquarium trade is vast. Pet stores import thousands of fish every month, the majority of which (58%) are considered to pose an ecological threat to native ecosystems. Our propagule pressure model suggests that approximately 2,500 fish (maximum 21,000 individuals) are likely released annually to the Puget Sound region by aquarists, and that water temperatures in many parts of Washington are suitable for establishment of populations. In conclusion, the aquarium trade may be a significant source of past and future invasions in the Pacific Northwest, and we recommend enhanced public education programs, greater regulation of the aquarium industry, and improved legislation of nonnative species in the ornamental trade. Close