Search

Search Results

• 21. [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

• 22. [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

• 23. [Article] Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses

  As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a ...

  Citation × Citation Citation Abstract Copy Title: Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses Author: Shortlidge, Erin Elizabeth Year: 2014 As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a terrestrial world out of water. Yet, there is a widely accepted dogma that moss reproductive success is solely dependent on rainfall events carrying swimming, bi-flagellate sperm across the landscape to reproductively mature and receptive female mosses--but this classic view of moss reproduction may be too simplistic. In this dissertation I test the assumptions of reproductive limitation in mosses and present novel findings in a basal, yet understudied terrestrial plant mating system. I find evidence of environmental desiccation tolerance in moss sperm, thus offering the potential for stress-tolerant gametes on the landscape possibly suited for various transport vectors, reminiscent of a pollen grain. To investigate the broad evolutionary implications of this newfound complexity in moss sexual reproduction, I tested classic tenets of plant-pollinator theory on the ancient mosses and their ubiquitous microarthropod inhabitants. Experimental results show that mosses and microarthropods are engaged in a "pollination-like" syndrome guided by sex-specific volatile cues that differentially affect microarthropod behavior. These data indicate an existing complex mutualistic relationship and provides new evidence of sexually dimorphic investment by male and female mosses into reproductive success. Further, these data put forth the idea that female mosses challenge an inherent mate limitation by investing into reproductive assurance via maintaining a relationship with microarthropods. Experimental work further confirms a role for invertebrates in moss reproductive success and tests mutualism theory through ongoing experiments. Such experiments include an assessment of moss genetic diversity, paternity, and male fitness traits as it relates to mosses with or without the presence of microarthropods, thereby testing for fitness benefits gained by mosses possibly engaged in a transport mutualism with microarthropods. I further tested mutualism, community ecology and moss sexual reproduction concepts in extreme geothermal moss populations living at the edges of inhabitable Earth, and results show that even geothermal moss canopies are diverse and host differential and abundant life. In a first field test of mutualism I found that although extreme heat stress may constrain sexual reproduction in mosses, a correlation between within-population moss genetic diversity and microarthropod abundances exists. To further examine mosses in extreme environments, and how these environments may constrain sexual reproductive success, I evaluated the effects of simulated warming on Antarctic moss physiology and reproductive biology. Data indicates that simulated warming relieves mosses of physiological stress, and results in a greater investment into primary productivity and sexual reproduction. These data support the hypothesis that with less stress, sexual reproduction is increased. Mosses are an ideal system by which to understand organisms that exist in environments ranging from the mesic to the extreme, in the laboratory and the field and even in the classroom, where the small functioning ecosystem of mosses can be used for discovery-based biology education as described in the Mosscosms curriculum. This work contributes significantly to the field of bryophyte and plant biology by revealing novel insights into the biotic and abiotic drivers of sexual reproduction in mosses. Title: Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses Author: Shortlidge, Erin Elizabeth Year: 2014 As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a terrestrial world out of water. Yet, there is a widely accepted dogma that moss reproductive success is solely dependent on rainfall events carrying swimming, bi-flagellate sperm across the landscape to reproductively mature and receptive female mosses--but this classic view of moss reproduction may be too simplistic. In this dissertation I test the assumptions of reproductive limitation in mosses and present novel findings in a basal, yet understudied terrestrial plant mating system. I find evidence of environmental desiccation tolerance in moss sperm, thus offering the potential for stress-tolerant gametes on the landscape possibly suited for various transport vectors, reminiscent of a pollen grain. To investigate the broad evolutionary implications of this newfound complexity in moss sexual reproduction, I tested classic tenets of plant-pollinator theory on the ancient mosses and their ubiquitous microarthropod inhabitants. Experimental results show that mosses and microarthropods are engaged in a "pollination-like" syndrome guided by sex-specific volatile cues that differentially affect microarthropod behavior. These data indicate an existing complex mutualistic relationship and provides new evidence of sexually dimorphic investment by male and female mosses into reproductive success. Further, these data put forth the idea that female mosses challenge an inherent mate limitation by investing into reproductive assurance via maintaining a relationship with microarthropods. Experimental work further confirms a role for invertebrates in moss reproductive success and tests mutualism theory through ongoing experiments. Such experiments include an assessment of moss genetic diversity, paternity, and male fitness traits as it relates to mosses with or without the presence of microarthropods, thereby testing for fitness benefits gained by mosses possibly engaged in a transport mutualism with microarthropods. I further tested mutualism, community ecology and moss sexual reproduction concepts in extreme geothermal moss populations living at the edges of inhabitable Earth, and results show that even geothermal moss canopies are diverse and host differential and abundant life. In a first field test of mutualism I found that although extreme heat stress may constrain sexual reproduction in mosses, a correlation between within-population moss genetic diversity and microarthropod abundances exists. To further examine mosses in extreme environments, and how these environments may constrain sexual reproductive success, I evaluated the effects of simulated warming on Antarctic moss physiology and reproductive biology. Data indicates that simulated warming relieves mosses of physiological stress, and results in a greater investment into primary productivity and sexual reproduction. These data support the hypothesis that with less stress, sexual reproduction is increased. Mosses are an ideal system by which to understand organisms that exist in environments ranging from the mesic to the extreme, in the laboratory and the field and even in the classroom, where the small functioning ecosystem of mosses can be used for discovery-based biology education as described in the Mosscosms curriculum. This work contributes significantly to the field of bryophyte and plant biology by revealing novel insights into the biotic and abiotic drivers of sexual reproduction in mosses. Close

• 24. [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

• 25. [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

• 26. [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

• 27. [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

• 28. [Article] Impact of Bythotrephes Invasion on Zooplankton Communities in Acid-Damaged and Recovered Lakes on the Boreal Shield

  Invasive species introductions into freshwater ecosystems have had a multitude of effects on aquatic communities. Few studies, however, have directly compared the impact of an invader on communities with ...

  Citation × Citation Citation Abstract Copy Title: Impact of Bythotrephes Invasion on Zooplankton Communities in Acid-Damaged and Recovered Lakes on the Boreal Shield Author: Strecker, Angela L., Arnott, Shelley E. Year: 2005 Invasive species introductions into freshwater ecosystems have had a multitude of effects on aquatic communities. Few studies, however, have directly compared the impact of an invader on communities with contrasting structure. Historically high levels and subsequent reductions of acid deposition have produced landscapes of lakes of varying acidity and zooplankton communitystructure. We conducted a 30-day enclosure experiment in Killarney Provincial Park, Ontario, Canada, to test the effects ofBythotrephes longimanus, an invasive invertebrate predator, on two contrasting zooplankton communities at different stages of recovery from acidification: recovered and acid damaged. Bythotrephes significantly decreased zooplankton biomass and abundance in both communities but had a greater negative effect on the abundance of zooplankton in the recovered community.Bythotrephes reduced species diversity of the recovered zooplankton community but not of the acid-damaged community. Species richness of both community types was unaffected by Bythotrephes predation. The effect of Bythotrephes on small cladocerans, a preferred prey type, differed between the community types and appeared to be related to density-dependent predation byBythotrephes. Both community- and species-level results suggest that recovered and acid-damaged zooplankton assemblages may be negatively affected by an invasion of Bythotrephes but that the specific response is dependent on the original community structure. Title: Impact of Bythotrephes Invasion on Zooplankton Communities in Acid-Damaged and Recovered Lakes on the Boreal Shield Author: Strecker, Angela L., Arnott, Shelley E. Year: 2005 Invasive species introductions into freshwater ecosystems have had a multitude of effects on aquatic communities. Few studies, however, have directly compared the impact of an invader on communities with contrasting structure. Historically high levels and subsequent reductions of acid deposition have produced landscapes of lakes of varying acidity and zooplankton communitystructure. We conducted a 30-day enclosure experiment in Killarney Provincial Park, Ontario, Canada, to test the effects ofBythotrephes longimanus, an invasive invertebrate predator, on two contrasting zooplankton communities at different stages of recovery from acidification: recovered and acid damaged. Bythotrephes significantly decreased zooplankton biomass and abundance in both communities but had a greater negative effect on the abundance of zooplankton in the recovered community.Bythotrephes reduced species diversity of the recovered zooplankton community but not of the acid-damaged community. Species richness of both community types was unaffected by Bythotrephes predation. The effect of Bythotrephes on small cladocerans, a preferred prey type, differed between the community types and appeared to be related to density-dependent predation byBythotrephes. Both community- and species-level results suggest that recovered and acid-damaged zooplankton assemblages may be negatively affected by an invasion of Bythotrephes but that the specific response is dependent on the original community structure. Close

• 29. [Article] Dispersal Limitation and Climate-Related Environmental Gradients Structure Microcrustacean Composition in Freshwater Lakes, Ellesmere Island, Canada

  Dramatic environmental change is expected in the Arctic, yet little is known about the occurrence and community composition of microcrustaceans in Arctic lakes and how this will be influenced by future ...

  Citation × Citation Citation Abstract Copy Title: Dispersal Limitation and Climate-Related Environmental Gradients Structure Microcrustacean Composition in Freshwater Lakes, Ellesmere Island, Canada Author: Strecker, Angela L., Milne, Rebecca, Arnott, Shelley E. Year: 2008 Dramatic environmental change is expected in the Arctic, yet little is known about the occurrence and community composition of microcrustaceans in Arctic lakes and how this will be influenced by future environmental change. We sampled and calculated relative abundances of microcrustacean species in 54 lakes on Ellesmere Island, Canada. New species records on Ellesmere Island included Daphnia umbra, Tachidius discipes, and Artemeopsis stefanssoni. Daphnia middendorffiana/tenebrosa was the most common taxon and often dominated microcrustacean assemblages, likely a result of its pigmentation, which offers resistance to ultraviolet radiation. Species richness was positively associated with nutrients, dissolved organic carbon (DOC), temperature, calcium, and conductivity and negatively affected by elevation. In contrast to most findings in temperate systems, we detected a negative relationship between species richness and surface area. Community composition was influenced by DOC, nutrients, and elevation but was also related to spatial variables, suggesting that spatial gradients in environmental conditions and dispersal are important drivers of differences among sites. Arctic ecosystems are expected to change rapidly in the coming years because of climate change and ozone thinning, and we expect that associated changes in DOC, temperature, and nutrients will affect microcrustacean species richness and distribution throughout the landscape. Title: Dispersal Limitation and Climate-Related Environmental Gradients Structure Microcrustacean Composition in Freshwater Lakes, Ellesmere Island, Canada Author: Strecker, Angela L., Milne, Rebecca, Arnott, Shelley E. Year: 2008 Dramatic environmental change is expected in the Arctic, yet little is known about the occurrence and community composition of microcrustaceans in Arctic lakes and how this will be influenced by future environmental change. We sampled and calculated relative abundances of microcrustacean species in 54 lakes on Ellesmere Island, Canada. New species records on Ellesmere Island included Daphnia umbra, Tachidius discipes, and Artemeopsis stefanssoni. Daphnia middendorffiana/tenebrosa was the most common taxon and often dominated microcrustacean assemblages, likely a result of its pigmentation, which offers resistance to ultraviolet radiation. Species richness was positively associated with nutrients, dissolved organic carbon (DOC), temperature, calcium, and conductivity and negatively affected by elevation. In contrast to most findings in temperate systems, we detected a negative relationship between species richness and surface area. Community composition was influenced by DOC, nutrients, and elevation but was also related to spatial variables, suggesting that spatial gradients in environmental conditions and dispersal are important drivers of differences among sites. Arctic ecosystems are expected to change rapidly in the coming years because of climate change and ozone thinning, and we expect that associated changes in DOC, temperature, and nutrients will affect microcrustacean species richness and distribution throughout the landscape. Close

• 30. [Article] Variation in the Response of Crustacean Zooplankton Species Richness and Composition to the Invasive Predator Bythotrephes Longimanus

  The predacious invertebrate Bythotrephes longimanus has invaded >90 freshwater lakes in North America. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; ...

  Citation × Citation Citation Abstract Copy Title: Variation in the Response of Crustacean Zooplankton Species Richness and Composition to the Invasive Predator Bythotrephes Longimanus Author: Strecker, Angela L., Arnott, Shelley E., Yan, Norman D., Girard, Robert Year: 2006 The predacious invertebrate Bythotrephes longimanus has invaded >90 freshwater lakes in North America. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; however, no study has examined the effect of B. longimanus throughout the ice-free season in more than one lake. We visited 10 invaded and 4 reference lakes every 2 weeks from May to September, collecting B. longimanus, crustacean zooplankton, and water chemistry samples. Composite samples were pooled across the study season for each lake. Bythotrephes longimanus significantly reduced cladoceran species richness, diversity, and abundance, and the total zooplankton community also exhibited decreased richness, diversity, and abundance. Seasonal sampling was better than synoptic surveys at detecting changes in abundance, but richness estimates were similar. As B. longimanus continues to spread across lake landscapes, we expect it will have profound impacts on local and regional richness and species distribution patterns. Title: Variation in the Response of Crustacean Zooplankton Species Richness and Composition to the Invasive Predator Bythotrephes Longimanus Author: Strecker, Angela L., Arnott, Shelley E., Yan, Norman D., Girard, Robert Year: 2006 The predacious invertebrate Bythotrephes longimanus has invaded >90 freshwater lakes in North America. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; however, no study has examined the effect of B. longimanus throughout the ice-free season in more than one lake. We visited 10 invaded and 4 reference lakes every 2 weeks from May to September, collecting B. longimanus, crustacean zooplankton, and water chemistry samples. Composite samples were pooled across the study season for each lake. Bythotrephes longimanus significantly reduced cladoceran species richness, diversity, and abundance, and the total zooplankton community also exhibited decreased richness, diversity, and abundance. Seasonal sampling was better than synoptic surveys at detecting changes in abundance, but richness estimates were similar. As B. longimanus continues to spread across lake landscapes, we expect it will have profound impacts on local and regional richness and species distribution patterns. Close