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• 1. [Article] The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville

  One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species ...

  Citation × Citation Citation Abstract Copy Title: The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville Author: de Rivera, Catherine E., Bliss-Ketchum, Leslie L. Year: 2010 One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species is habitat fragmentation. The ability for individuals to travel between subpopulations is the key to genetic diversity as well as ultimately the survival of the species. Considering these impacts and management goals to increase habitat connectivity, increased attention has been given to creating road design that reduces wildlife collisions. Most studies, however, have been in other countries or regions and most focus on connectivity for just one or a few species and rarely in urban settings. This study examines the effectiveness of a variety of under-road passage structures for a community of animals in an urban wetland. Wildlife passage was taken into great consideration in the construction of the Boeckman Road Extension, the new road (2006) in Wilsonville, Oregon, examined in this study. As a result it includes a bridge, two box culverts and eleven round concrete culverts to facilitate wildlife passage as well as a mammal fence atop an amphibian/reptile wall. In order to monitor passage use we used a combination of sand-track monitoring and motion-detect cameras. We compared passage structure use to movement in the habitats surrounding the road by monitoring four habitat transects in addition to the passage structures (Road transect). We also conducted tag and release studies targeted to small mammals. Finally, camera data collected in passage structures were compared to camera monitoring at the end of the exclusionary fencing. A total of 26 species were detected in this study, 73% (19) of which were found to be using passage structures. 15% (4) of the identified species were detected on transects but not in passages and 11.5% (3) were detected in locations other than transects or passage structures. The bridge structure provided passage to the highest number of species (16), followed by the 24” and 18” culverts, which had a combined total of 11 species, and lastly the 9x4 culverts, which were flooded, with 2 species detected. Our results indicate that large and medium mammals overall did not use passages less than would be expected based on their local movement in habitats. In pit and Sherman traps sixteen of the 48 small mammals that were captured and tagged were re-caught, but only four of these moved from one transect to another, with two moving away from the road and the other two moving toward and under the road. Of the species detected with cameras at the passage structures and circumventing fencing, excluding small mammals, reptiles and amphibians (139), 19% (33) were found potentially crossing on the road surface. The proportion of deer detected using over-road crossings (23%) is of particular concern for driver safety. The bridge structure provided the greatest passage, in not only frequency of crossings but also species present. When maintenance factors, driver safety and species of greatest concern are included, the higher cost of the bridge structure would likely be even further balanced by the benefits. This study highlights the effectiveness and potential problems (and possible fixes) of some of the passage and prevention structures. Including passage and prevention structures such as these in road design is imperative for habitat connectivity and the need for this becomes even more apparent as Oregon’s native wildlife face an ever increasing urban landscape as well as the potential impacts of climate change. Title: The Effectiveness of Vertebrate Passage and Prevention Structures: A Study of Boeckman Road in Wilsonville Author: de Rivera, Catherine E., Bliss-Ketchum, Leslie L. Year: 2010 One of the most obvious impacts roads have on the natural world is direct mortality to individual animals that attempt to cross roads. A less obvious but likely more important impact of roads on many species is habitat fragmentation. The ability for individuals to travel between subpopulations is the key to genetic diversity as well as ultimately the survival of the species. Considering these impacts and management goals to increase habitat connectivity, increased attention has been given to creating road design that reduces wildlife collisions. Most studies, however, have been in other countries or regions and most focus on connectivity for just one or a few species and rarely in urban settings. This study examines the effectiveness of a variety of under-road passage structures for a community of animals in an urban wetland. Wildlife passage was taken into great consideration in the construction of the Boeckman Road Extension, the new road (2006) in Wilsonville, Oregon, examined in this study. As a result it includes a bridge, two box culverts and eleven round concrete culverts to facilitate wildlife passage as well as a mammal fence atop an amphibian/reptile wall. In order to monitor passage use we used a combination of sand-track monitoring and motion-detect cameras. We compared passage structure use to movement in the habitats surrounding the road by monitoring four habitat transects in addition to the passage structures (Road transect). We also conducted tag and release studies targeted to small mammals. Finally, camera data collected in passage structures were compared to camera monitoring at the end of the exclusionary fencing. A total of 26 species were detected in this study, 73% (19) of which were found to be using passage structures. 15% (4) of the identified species were detected on transects but not in passages and 11.5% (3) were detected in locations other than transects or passage structures. The bridge structure provided passage to the highest number of species (16), followed by the 24” and 18” culverts, which had a combined total of 11 species, and lastly the 9x4 culverts, which were flooded, with 2 species detected. Our results indicate that large and medium mammals overall did not use passages less than would be expected based on their local movement in habitats. In pit and Sherman traps sixteen of the 48 small mammals that were captured and tagged were re-caught, but only four of these moved from one transect to another, with two moving away from the road and the other two moving toward and under the road. Of the species detected with cameras at the passage structures and circumventing fencing, excluding small mammals, reptiles and amphibians (139), 19% (33) were found potentially crossing on the road surface. The proportion of deer detected using over-road crossings (23%) is of particular concern for driver safety. The bridge structure provided the greatest passage, in not only frequency of crossings but also species present. When maintenance factors, driver safety and species of greatest concern are included, the higher cost of the bridge structure would likely be even further balanced by the benefits. This study highlights the effectiveness and potential problems (and possible fixes) of some of the passage and prevention structures. Including passage and prevention structures such as these in road design is imperative for habitat connectivity and the need for this becomes even more apparent as Oregon’s native wildlife face an ever increasing urban landscape as well as the potential impacts of climate change. Close

• 2. [Article] Ecological Investigations to Select Mitigation Options to Reduce Vehicle-Caused Mortality of a Threatened Butterfly

  Whereas roads that bisect habitat are known to decrease population size through animal-vehicle collisions or interruption of key life history events, it is not always obvious how to reduce such impacts, ...

  Citation × Citation Citation Abstract Copy Title: Ecological Investigations to Select Mitigation Options to Reduce Vehicle-Caused Mortality of a Threatened Butterfly Author: Zielin, Sara B., Littlejohn, Jalene, de Rivera, Catherine E., Smith, Winston P., Jacobson, Sandra L. Year: 2016 Whereas roads that bisect habitat are known to decrease population size through animal-vehicle collisions or interruption of key life history events, it is not always obvious how to reduce such impacts, especially for flying organisms. We needed a quick, cost-efficient and effective way to determine how best to decrease vehicle-caused mortality while maintaining habitat connectivity for the federally listed Oregon silverspot butterfly, Speyeria zerene hippolyta. Therefore, we gathered targeted ecological information that informed selection of a mitigation option prior to implementation. We sampled butterfly behavior and environmental conditions along a highway and conducted a small-scale experiment along a decommissioned road corridor used by these butterflies. Using our findings, we recommended vegetation management and helped managers eliminate options they were considering that would be ineffective such as increasing shade or wind in the road, and installing fencing or hedgerows aimed at directing flight above traffic. This quick and inexpensive approach of using ecological observations and small-scale experiments to evaluate the likely success of each available mitigation option can be used to determine effective, species-specific solutions for reducing traffic impacts on pollinators and other small, flying organisms of conservation concern. Title: Ecological Investigations to Select Mitigation Options to Reduce Vehicle-Caused Mortality of a Threatened Butterfly Author: Zielin, Sara B., Littlejohn, Jalene, de Rivera, Catherine E., Smith, Winston P., Jacobson, Sandra L. Year: 2016 Whereas roads that bisect habitat are known to decrease population size through animal-vehicle collisions or interruption of key life history events, it is not always obvious how to reduce such impacts, especially for flying organisms. We needed a quick, cost-efficient and effective way to determine how best to decrease vehicle-caused mortality while maintaining habitat connectivity for the federally listed Oregon silverspot butterfly, Speyeria zerene hippolyta. Therefore, we gathered targeted ecological information that informed selection of a mitigation option prior to implementation. We sampled butterfly behavior and environmental conditions along a highway and conducted a small-scale experiment along a decommissioned road corridor used by these butterflies. Using our findings, we recommended vegetation management and helped managers eliminate options they were considering that would be ineffective such as increasing shade or wind in the road, and installing fencing or hedgerows aimed at directing flight above traffic. This quick and inexpensive approach of using ecological observations and small-scale experiments to evaluate the likely success of each available mitigation option can be used to determine effective, species-specific solutions for reducing traffic impacts on pollinators and other small, flying organisms of conservation concern. Close

• 3. [Article] Small Tidal Channels Improve Foraging Opportunities for Calidris Shorebirds

  Estuarine intertidal habitats are heterogeneous, therefore migratory shorebirds are expected to forage in microhabitats where they can maximize their energy intake. Identifying proximate factors that migratory ...

  Citation × Citation Citation Abstract Copy Title: Small Tidal Channels Improve Foraging Opportunities for Calidris Shorebirds Author: Miller, Aileen K., de Rivera, Catherine E. Year: 2014 Estuarine intertidal habitats are heterogeneous, therefore migratory shorebirds are expected to forage in microhabitats where they can maximize their energy intake. Identifying proximate factors that migratory shorebirds use to accept or reject a particular habitat patch will help land managers make conservation and restoration decisions that provide the greatest benefits to shorebird populations during migration, a period of intense energy usage. We examined whether small semipermanent tidal channels were preferentially used by foraging Western Sandpipers (Calidris mauri) and Dunlins (C. alpina) during a spring migratory stopover in Bandon Marsh, an Oregon, USA, estuary. Further, we tested alternative hypotheses about how channels might be beneficial to shorebirds by examining infauna abundance, composition, and depth alongside channels compared with that in open mudflats. The densities of Western Sandpipers and Dunlins were at least 4 times higher along channels than in open mudflat habitats. Infauna along channels were twice as abundant as those in the surrounding mudflats, and infauna were generally found closer to the surface. Furthermore, sediment alongside channels required less than half the force to probe, probably increasing shorebirds' overall access to prey. We conclude that shorebirds selected microhabitats near channels because of the greater food abundance and availability. Additional evidence suggested that another microhabitat, patches of red algae (Gracilaria sp.), may also have conferred advantages on foraging shorebirds. Channels may be a valuable microhabitat to consider when selecting conservation areas for shorebirds, and maintaining channels (e.g., through maintaining natural hydrology and sedimentation patterns) should be considered in management practices. Title: Small Tidal Channels Improve Foraging Opportunities for Calidris Shorebirds Author: Miller, Aileen K., de Rivera, Catherine E. Year: 2014 Estuarine intertidal habitats are heterogeneous, therefore migratory shorebirds are expected to forage in microhabitats where they can maximize their energy intake. Identifying proximate factors that migratory shorebirds use to accept or reject a particular habitat patch will help land managers make conservation and restoration decisions that provide the greatest benefits to shorebird populations during migration, a period of intense energy usage. We examined whether small semipermanent tidal channels were preferentially used by foraging Western Sandpipers (Calidris mauri) and Dunlins (C. alpina) during a spring migratory stopover in Bandon Marsh, an Oregon, USA, estuary. Further, we tested alternative hypotheses about how channels might be beneficial to shorebirds by examining infauna abundance, composition, and depth alongside channels compared with that in open mudflats. The densities of Western Sandpipers and Dunlins were at least 4 times higher along channels than in open mudflat habitats. Infauna along channels were twice as abundant as those in the surrounding mudflats, and infauna were generally found closer to the surface. Furthermore, sediment alongside channels required less than half the force to probe, probably increasing shorebirds' overall access to prey. We conclude that shorebirds selected microhabitats near channels because of the greater food abundance and availability. Additional evidence suggested that another microhabitat, patches of red algae (Gracilaria sp.), may also have conferred advantages on foraging shorebirds. Channels may be a valuable microhabitat to consider when selecting conservation areas for shorebirds, and maintaining channels (e.g., through maintaining natural hydrology and sedimentation patterns) should be considered in management practices. Close

• 4. [Article] A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume

  Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of ...

  Citation × Citation Citation Abstract Copy Title: A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume Author: Jacobson, Sandra L., Bliss-Ketchum, Leslie L., de Rivera, Catherine E., Smith, Winston P. Year: 2016 Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of populations. Investigators have attempted to use traffic volume, the number of vehicles passing a point on a road segment, to predict effects to wildlife populations approximately linearly and along taxonomic lines; however, taxonomic groupings cannot provide sound predictions because closely related species often respond differently. We assess the role of wildlife behavioral responses to traffic volume as a tool to predict barrier effects from vehicle-caused mortality and avoidance, to provide an early warning system that recognizes traffic volume as a trigger for mitigation, and to better interpret roadkill data. We propose four categories of behavioral response based on the perceived danger to traffic: Nonresponders, Pausers, Speeders, and Avoiders. Nonresponders attempt to cross highways regardless of traffic volume. Pausers stop in the face of danger so have a low probability of successful crossing when traffic volume increases. Hence, highway barrier effects are primarily due to mortality for Nonresponders and Pausers at high traffic volumes. Speeders run away from danger but are unable to do so successfully as traffic volume increases. At moderate to high volume, Speeders are repelled by traffic danger. Avoiders face lower mortality than other categories because they begin to avoid traffic at relatively low traffic volumes. Hence, avoidance causes barrier effects more than mortality for Speeders and Avoiders even at relatively moderate traffic volumes. By considering a species’ risk-avoidance response to traffic, managers can make more appropriate and timely decisions to mitigate effects before populations decline or become locally extinct. Title: A Behavior-Based Framework for Assessing Barrier Effects to Wildlife from Vehicle Traffic Volume Author: Jacobson, Sandra L., Bliss-Ketchum, Leslie L., de Rivera, Catherine E., Smith, Winston P. Year: 2016 Roads, while central to the function of human society, create barriers to animal movement through collisions and habitat fragmentation. Barriers to animal movement affect the evolution and trajectory of populations. Investigators have attempted to use traffic volume, the number of vehicles passing a point on a road segment, to predict effects to wildlife populations approximately linearly and along taxonomic lines; however, taxonomic groupings cannot provide sound predictions because closely related species often respond differently. We assess the role of wildlife behavioral responses to traffic volume as a tool to predict barrier effects from vehicle-caused mortality and avoidance, to provide an early warning system that recognizes traffic volume as a trigger for mitigation, and to better interpret roadkill data. We propose four categories of behavioral response based on the perceived danger to traffic: Nonresponders, Pausers, Speeders, and Avoiders. Nonresponders attempt to cross highways regardless of traffic volume. Pausers stop in the face of danger so have a low probability of successful crossing when traffic volume increases. Hence, highway barrier effects are primarily due to mortality for Nonresponders and Pausers at high traffic volumes. Speeders run away from danger but are unable to do so successfully as traffic volume increases. At moderate to high volume, Speeders are repelled by traffic danger. Avoiders face lower mortality than other categories because they begin to avoid traffic at relatively low traffic volumes. Hence, avoidance causes barrier effects more than mortality for Speeders and Avoiders even at relatively moderate traffic volumes. By considering a species’ risk-avoidance response to traffic, managers can make more appropriate and timely decisions to mitigate effects before populations decline or become locally extinct. Close

• 5. [Article] The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats

  Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation ...

  Citation × Citation Citation Abstract Copy Title: The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats Author: McClees, Whitney, de Rivera, Catherine E. Year: 2017 Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation is limiting the spread of non-native species, while other research has indicated that it is dispersal-driven. To determine the effects of dispersal limitation and predation on the risk to surrounding habitats of being invaded by non-native species established on marina docks, we used a three-factor design, deploying seven unglazed ceramic panels per each treatment combination of 1) inside versus outside a marina in Yaquina Bay, Oregon; 2) cage keeping out predators >mesh size, no cage, or partial cage; 3) fixed near the substrata (benthic) versus floating 1m below the surface. We also moved panels of either adults or recruits from floating in the marina to any of the treatment combinations to test if they would have lower survival outside by the substrate. The community on panels suspended in the marina only minimally overlapped with panels outside of the marina near the bottom. However, there was no difference between the cage treatments, which suggests that predators excluded by the cages are not responsible for the observed differences in species richness or composition. Title: The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats Author: McClees, Whitney, de Rivera, Catherine E. Year: 2017 Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation is limiting the spread of non-native species, while other research has indicated that it is dispersal-driven. To determine the effects of dispersal limitation and predation on the risk to surrounding habitats of being invaded by non-native species established on marina docks, we used a three-factor design, deploying seven unglazed ceramic panels per each treatment combination of 1) inside versus outside a marina in Yaquina Bay, Oregon; 2) cage keeping out predators >mesh size, no cage, or partial cage; 3) fixed near the substrata (benthic) versus floating 1m below the surface. We also moved panels of either adults or recruits from floating in the marina to any of the treatment combinations to test if they would have lower survival outside by the substrate. The community on panels suspended in the marina only minimally overlapped with panels outside of the marina near the bottom. However, there was no difference between the cage treatments, which suggests that predators excluded by the cages are not responsible for the observed differences in species richness or composition. Close

• 6. [Article] Accelerated Erosion of Saltmarshes Infested by the Non-Native Burrowing Crustacean Sphaeroma Quoianum

  Lateral erosion of saltmarshes is affected by many abiotic and biotic factors. While abiotic factors are typically regarded as primary drivers of erosion, biotic influences such as burrowing or bioturbating ...

  Citation × Citation Citation Abstract Copy Title: Accelerated Erosion of Saltmarshes Infested by the Non-Native Burrowing Crustacean Sphaeroma Quoianum Author: Davidson, Timothy Mathias, de Rivera, Catherine E. Year: 2010 Lateral erosion of saltmarshes is affected by many abiotic and biotic factors. While abiotic factors are typically regarded as primary drivers of erosion, biotic influences such as burrowing or bioturbating taxa can also extensively modify the physical structure of this marine habitat. Many estuaries on the Pacific coast of North America have been invaded by populations of the burrowing non-native isopod Sphaeroma quoianum, which are thought to exacerbate the erosion of saltmarshes. We conducted a mensurative experiment to examine the relationship between populations of S. quoianum and lateral erosion rate of saltmarshes in Coos Bay, Oregon, USA. After 1 yr, we measured higher lateral erosion rates, more undercutting, and higher numbers of calved and slumped marsh sections in marsh sites infested by S. quoianum than in uninfested sites. This effect was also consistent at smaller spatial scales: we found lateral erosion was 300% higher in burrowed areas than in adjacent (within approx. 1 m) unburrowed areas within infested sites. Our results suggest that the prodigious burrowing by dense populations of S. quoianum can accelerate erosion rates in saltmarshes and are substantial geomorphic agents of change in estuaries on the Pacific coast of North America. Title: Accelerated Erosion of Saltmarshes Infested by the Non-Native Burrowing Crustacean Sphaeroma Quoianum Author: Davidson, Timothy Mathias, de Rivera, Catherine E. Year: 2010 Lateral erosion of saltmarshes is affected by many abiotic and biotic factors. While abiotic factors are typically regarded as primary drivers of erosion, biotic influences such as burrowing or bioturbating taxa can also extensively modify the physical structure of this marine habitat. Many estuaries on the Pacific coast of North America have been invaded by populations of the burrowing non-native isopod Sphaeroma quoianum, which are thought to exacerbate the erosion of saltmarshes. We conducted a mensurative experiment to examine the relationship between populations of S. quoianum and lateral erosion rate of saltmarshes in Coos Bay, Oregon, USA. After 1 yr, we measured higher lateral erosion rates, more undercutting, and higher numbers of calved and slumped marsh sections in marsh sites infested by S. quoianum than in uninfested sites. This effect was also consistent at smaller spatial scales: we found lateral erosion was 300% higher in burrowed areas than in adjacent (within approx. 1 m) unburrowed areas within infested sites. Our results suggest that the prodigious burrowing by dense populations of S. quoianum can accelerate erosion rates in saltmarshes and are substantial geomorphic agents of change in estuaries on the Pacific coast of North America. Close

• 7. [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

• 8. [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

• 9. [Article] Damage and Alteration of Mangroves Inhabited by a Marine Wood-Borer

  Animals can exert a strong influence on the structure and function of foundation species such as mangroves. Because mangroves live at the interface of land and sea, both terrestrial and marine species ...

  Citation × Citation Citation Abstract Copy Title: Damage and Alteration of Mangroves Inhabited by a Marine Wood-Borer Author: Davidson, Timothy Mathias, de Rivera, Catherine E., Hsieh, Hwey-Lian Year: 2014 Animals can exert a strong influence on the structure and function of foundation species such as mangroves. Because mangroves live at the interface of land and sea, both terrestrial and marine species affect them, including numerous herbivores and boring species. These organisms can affect the fecundity, performance, and morphology of mangroves. In a mangrove stand in southwestern Taiwan, we discovered that mangroves were extensively damaged by woodboring isopods Sphaeroma terebrans. We examined the relationships between burrowing damage from S. terebrans and metrics of mangrove fecundity, performance, and morphology. Individuals of Rhizophora stylosa that were more burrowed by isopods had significantly fewer propagules, fewer ground roots stabilizing the tree, smaller leaves, and more non-foliated twigs. Similarly, Avicennia marina with more burrows had fewer pneumatophores and lenticels (used for gaseous exchange), and pneumatophores with more necrotic tissue. The most heavily damaged trees were hollowed-out with burrows (A. marina) or fell over when their supportive root system failed (R. stylosa). These correlations suggest that marine wood-borers can negatively influence mangroves and alter tree morphology, although other stressors may also be involved. While studies have examined the effects of isopods on root-level production, we provide the first quantitative evidence that localized burrowing damage is correlated with tree-level effects. These results are consistent with other literature demonstrating the importance of sub-lethal damage by borers in shaping foundation species. Such damage may have cascading effects on the diverse assemblages of marine and terrestrial biota that use mangroves as habitat. Title: Damage and Alteration of Mangroves Inhabited by a Marine Wood-Borer Author: Davidson, Timothy Mathias, de Rivera, Catherine E., Hsieh, Hwey-Lian Year: 2014 Animals can exert a strong influence on the structure and function of foundation species such as mangroves. Because mangroves live at the interface of land and sea, both terrestrial and marine species affect them, including numerous herbivores and boring species. These organisms can affect the fecundity, performance, and morphology of mangroves. In a mangrove stand in southwestern Taiwan, we discovered that mangroves were extensively damaged by woodboring isopods Sphaeroma terebrans. We examined the relationships between burrowing damage from S. terebrans and metrics of mangrove fecundity, performance, and morphology. Individuals of Rhizophora stylosa that were more burrowed by isopods had significantly fewer propagules, fewer ground roots stabilizing the tree, smaller leaves, and more non-foliated twigs. Similarly, Avicennia marina with more burrows had fewer pneumatophores and lenticels (used for gaseous exchange), and pneumatophores with more necrotic tissue. The most heavily damaged trees were hollowed-out with burrows (A. marina) or fell over when their supportive root system failed (R. stylosa). These correlations suggest that marine wood-borers can negatively influence mangroves and alter tree morphology, although other stressors may also be involved. While studies have examined the effects of isopods on root-level production, we provide the first quantitative evidence that localized burrowing damage is correlated with tree-level effects. These results are consistent with other literature demonstrating the importance of sub-lethal damage by borers in shaping foundation species. Such damage may have cascading effects on the diverse assemblages of marine and terrestrial biota that use mangroves as habitat. Close

• 10. [Article] Broad-Scale Non-indigenous Species Monitoring along the West Coast in National Marine Sanctuaries and National Estuarine Research Reserves

  Nonindigenous species have caused substantial environmental and economic damage to coastal areas. Moreover, the extent and impacts of nonindigenous species are increasing over time. To develop predictive ...

  Citation × Citation Citation Abstract Copy Title: Broad-Scale Non-indigenous Species Monitoring along the West Coast in National Marine Sanctuaries and National Estuarine Research Reserves Author: de Rivera, Catherine E., Ruiz, Greg, Crooks, Jeff, Wasson, Kerstin, Lonhart, Steve, Fofonoff, Paul, Steves, Brian, Rumrill, Steven S., Brancato, Mary Sue, Pegau, Scott, Bulthuis, Doug, Preisler, Rikke Kvist, Schoch, Carl, Bowlby, Ed, DeVogelaere, Andrew, Crawford, Maurice, Gittings, Steve, Hines, Anson, Takata, Lynn, Larson, Kristen, Huber, Tami, Leyman, Anne Marie, Collinetti, Esther, Pascot, Tiffany, Shull, Suzanne, Anderson, Mary, Powell, Sue Year: 2005 Nonindigenous species have caused substantial environmental and economic damage to coastal areas. Moreover, the extent and impacts of nonindigenous species are increasing over time. To develop predictive models and to identify which areas should be targeted for impact mitigation or early detection, we need a basic foundation of knowledge about the spatial and temporal patterns of invasions. This project was developed because we lacked the necessary data to rigorously evaluate the patterns of coastal invasions. This collaborative project, between the Smithsonian Environmental Research Center, the National Estuarine Research Reserve System (NERRS) and the National Marine Sanctuary Program (NMSP), established a rigorous, largescale monitoring and research program for invasive species in nine protected coastal areas along the US West Coast from San Diego, CA, to Kachemak Bay, AK. Our research included two components, broad-scale and site-specific projects. The broad-scale component focused on using standardized protocols to collect data on the composition of fouling communities and nearshore fish and crabs. We collected data from 310 settling plates and 140 traps across nine NERRS Reserves and NMSP Sanctuaries. The four most common taxa on the settling plates were Bryozoa, Tunicata, Cirripedia, and Hydrozoa. We identified these four taxa and also Nudibranchia, a mobile molluscan taxa often associated with fouling organisms, to species and noted which were nonindigenous. We found 132 species in the 5 taxa under study. NIS accounted for over one quarter of the diversity in these taxa, with 31 NIS identified. Over half of tunicate species were non-native. The documented NIS included two new US west coast sitings plus 3 other range extensions. We documented two patterns in NIS, a latitudinal pattern and differences between NIS impacts in marinas versus non-marina sites; research on salinity differences is still underway. Both the number and percent of NIS decreased with increasing latitude. Tijuana River had the most, 21, NIS and Monterey Bay had the highest proportion of NIS (57%). The same pattern of decreasing NIS with increasing latitude was observed when we examined Tunicata only and Bryozoa only. Across latitudes, plates in marinas were more impacted by NIS than were plates in more natural areas. All NIS but one were found at marinas, whereas only half the NIS were found at the non-marina sites. In addition, NIS at marinas accounted for almost 80% of the NIS per site. Therefore, we were able to provide information on the relative risk of invasions for different taxonomic groups and geographic regions. The spatial and habitat patterns can be used for future predictions and will be of even more value once they are confirmed with additional taxonomic groups and hypothesis-driven studies that will continue from this initial study. Our broad-scale trapping study illustrated how recently-introduced NIS quickly can become numerically dominant. Although we only found Carcinus maenas at Elkhorn Slough NERR, this recently introduced nonindigenous crab was very common at this Reserve and was the most abundant crab in our traps at 3 of 7 Elkhorn sites. The site-specific projects were conducted at each Reserve plus Olympic Coast and Monterey Bay Sanctuaries. Several are serving as the first important step in longer term research, such as examining whether a change in shipping policy in Kachemak Bay will increase NIS. Others, such as the South Slough project examining the effect of a salinity cline on the number and proportion of NIS, will be expanded to test hypotheses across several protected areas. Many of these site-specific projects still need further analyses, and analysis is underway. Title: Broad-Scale Non-indigenous Species Monitoring along the West Coast in National Marine Sanctuaries and National Estuarine Research Reserves Author: de Rivera, Catherine E., Ruiz, Greg, Crooks, Jeff, Wasson, Kerstin, Lonhart, Steve, Fofonoff, Paul, Steves, Brian, Rumrill, Steven S., Brancato, Mary Sue, Pegau, Scott, Bulthuis, Doug, Preisler, Rikke Kvist, Schoch, Carl, Bowlby, Ed, DeVogelaere, Andrew, Crawford, Maurice, Gittings, Steve, Hines, Anson, Takata, Lynn, Larson, Kristen, Huber, Tami, Leyman, Anne Marie, Collinetti, Esther, Pascot, Tiffany, Shull, Suzanne, Anderson, Mary, Powell, Sue Year: 2005 Nonindigenous species have caused substantial environmental and economic damage to coastal areas. Moreover, the extent and impacts of nonindigenous species are increasing over time. To develop predictive models and to identify which areas should be targeted for impact mitigation or early detection, we need a basic foundation of knowledge about the spatial and temporal patterns of invasions. This project was developed because we lacked the necessary data to rigorously evaluate the patterns of coastal invasions. This collaborative project, between the Smithsonian Environmental Research Center, the National Estuarine Research Reserve System (NERRS) and the National Marine Sanctuary Program (NMSP), established a rigorous, largescale monitoring and research program for invasive species in nine protected coastal areas along the US West Coast from San Diego, CA, to Kachemak Bay, AK. Our research included two components, broad-scale and site-specific projects. The broad-scale component focused on using standardized protocols to collect data on the composition of fouling communities and nearshore fish and crabs. We collected data from 310 settling plates and 140 traps across nine NERRS Reserves and NMSP Sanctuaries. The four most common taxa on the settling plates were Bryozoa, Tunicata, Cirripedia, and Hydrozoa. We identified these four taxa and also Nudibranchia, a mobile molluscan taxa often associated with fouling organisms, to species and noted which were nonindigenous. We found 132 species in the 5 taxa under study. NIS accounted for over one quarter of the diversity in these taxa, with 31 NIS identified. Over half of tunicate species were non-native. The documented NIS included two new US west coast sitings plus 3 other range extensions. We documented two patterns in NIS, a latitudinal pattern and differences between NIS impacts in marinas versus non-marina sites; research on salinity differences is still underway. Both the number and percent of NIS decreased with increasing latitude. Tijuana River had the most, 21, NIS and Monterey Bay had the highest proportion of NIS (57%). The same pattern of decreasing NIS with increasing latitude was observed when we examined Tunicata only and Bryozoa only. Across latitudes, plates in marinas were more impacted by NIS than were plates in more natural areas. All NIS but one were found at marinas, whereas only half the NIS were found at the non-marina sites. In addition, NIS at marinas accounted for almost 80% of the NIS per site. Therefore, we were able to provide information on the relative risk of invasions for different taxonomic groups and geographic regions. The spatial and habitat patterns can be used for future predictions and will be of even more value once they are confirmed with additional taxonomic groups and hypothesis-driven studies that will continue from this initial study. Our broad-scale trapping study illustrated how recently-introduced NIS quickly can become numerically dominant. Although we only found Carcinus maenas at Elkhorn Slough NERR, this recently introduced nonindigenous crab was very common at this Reserve and was the most abundant crab in our traps at 3 of 7 Elkhorn sites. The site-specific projects were conducted at each Reserve plus Olympic Coast and Monterey Bay Sanctuaries. Several are serving as the first important step in longer term research, such as examining whether a change in shipping policy in Kachemak Bay will increase NIS. Others, such as the South Slough project examining the effect of a salinity cline on the number and proportion of NIS, will be expanded to test hypotheses across several protected areas. Many of these site-specific projects still need further analyses, and analysis is underway. Close