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• 31. [Article] Bridging environmental physiology and community ecology : temperature effects at the community level

  Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how ...

  Citation × Citation Citation Abstract Copy Title: Bridging environmental physiology and community ecology : temperature effects at the community level Author: Iles, Alison C. Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how interactions are expected to change with climate and how to incorporate them into climate change models. Much of the variability in species interaction strengths may be governed by fundamental constraints on physiological rates, possibly providing a framework for including species interactions into climate change models. Metabolic rates, ingestion rates and many other physiological rates are relatively predictable from body size and body temperature due to constraints imposed by the physical and chemical laws that govern fluid dynamics and the kinetics of biochemical reaction times. My dissertation assesses the usefulness of this framework by exploring the community-level consequences of physiological constraints. In Chapter 2, I incorporated temperature and body size scaling into the biological rate parameters of a series of realistically structured trophic network models. The relative magnitude of the temperature scaling parameters affecting consumer energetic costs (metabolic rates) and energetic gains (ingestion rates) determined how consumer energetic efficiency changed with temperature. I systematically changed consumer energetic efficiency and examined the sensitivity of network stability and species persistence to various temperatures. I found that a species' probability of extinction depended primarily on the effects of organismal physiology (body size and energetic efficiency with respect to temperature) and secondarily on the effects of local food web structure (trophic level and consumer generality). This suggests that physiology is highly influential on the structure and dynamics of ecological communities. If consumer energetic efficiency declined as temperature increased, that is, species did best at lower temperatures, then the simulated networks had greater stability at lower temperatures. The opposite scenario resulted in greater stability at higher temperatures. Thus, much of the community-level response depends on what species energetic efficiencies at the organismal-level really are, which formed the research question for Chapter 3: How does consumer energetic efficiency change with temperature? Existing evidence is scarce but suggestive of decreasing consumer energetic efficiency with increasing temperature. I tested this hypothesis on seven rocky intertidal invertebrate species by measuring the relative temperature scaling of their metabolic and ingestion rates as well as consumer interaction strength under lab conditions. Energetic efficiencies of these rocky intertidal invertebrates declined and species interaction strengths tended to increase with temperature. Thus, in the rocky intertidal, the mechanistic effect of temperature would be to lower community stability at higher temperatures. Chapter 4 tests if the mechanistic effects of temperature on ingestion rates and species interaction strengths seen in the lab are apparent under field conditions. Bruce Menge and I related bio-mimetic estimates of body temperatures to estimates of per capita mussel ingestion rates and species interaction strengths by the ochre sea star Pisaster ochraceus, a keystone predator of the rocky intertidal. We found a strong, positive effect of body temperature on both per capita ingestion rates and interaction strengths. However, the effects of season and the unique way in which P. ochraceus regulates body temperatures were also apparent, leaving room for adaptation and acclimation to partially compensate for the mechanistic constraint of body temperature. Community structure of the rocky intertidal is associated with environmental forcing due to upwelling, which delivers cold, nutrient rich water to the nearshore environment. As upwelling is driven by large-scale atmospheric pressure gradients, climate change has the potential to affect a wide range of significant ecological processes through changes in water temperature. In Chapter 5, my coauthors and I identified long-term trends in the phenology of upwelling events that are consistent with climate change predictions: upwelling events are becoming stronger and longer. As expected, longer upwelling events were related to lower average water temperatures in the rocky intertidal. Furthermore, recruitment rates of barnacles and mussels were associated with the phenology of upwelling events. Thus climate change is altering the mode and the tempo of environmental forcing in nearshore ecosystems, with ramifications for community structure and function. Ongoing, long-term changes in environmental forcing in rocky intertidal ecosystems provide an opportunity to understand how temperature shapes community structure and the ramifications of climate change. My dissertation research demonstrates that the effect of temperature on organismal performance is an important force structuring ecological communities and has potential as a tractable framework for predicting the community level effects of climate change. Title: Bridging environmental physiology and community ecology : temperature effects at the community level Author: Iles, Alison C. Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how interactions are expected to change with climate and how to incorporate them into climate change models. Much of the variability in species interaction strengths may be governed by fundamental constraints on physiological rates, possibly providing a framework for including species interactions into climate change models. Metabolic rates, ingestion rates and many other physiological rates are relatively predictable from body size and body temperature due to constraints imposed by the physical and chemical laws that govern fluid dynamics and the kinetics of biochemical reaction times. My dissertation assesses the usefulness of this framework by exploring the community-level consequences of physiological constraints. In Chapter 2, I incorporated temperature and body size scaling into the biological rate parameters of a series of realistically structured trophic network models. The relative magnitude of the temperature scaling parameters affecting consumer energetic costs (metabolic rates) and energetic gains (ingestion rates) determined how consumer energetic efficiency changed with temperature. I systematically changed consumer energetic efficiency and examined the sensitivity of network stability and species persistence to various temperatures. I found that a species' probability of extinction depended primarily on the effects of organismal physiology (body size and energetic efficiency with respect to temperature) and secondarily on the effects of local food web structure (trophic level and consumer generality). This suggests that physiology is highly influential on the structure and dynamics of ecological communities. If consumer energetic efficiency declined as temperature increased, that is, species did best at lower temperatures, then the simulated networks had greater stability at lower temperatures. The opposite scenario resulted in greater stability at higher temperatures. Thus, much of the community-level response depends on what species energetic efficiencies at the organismal-level really are, which formed the research question for Chapter 3: How does consumer energetic efficiency change with temperature? Existing evidence is scarce but suggestive of decreasing consumer energetic efficiency with increasing temperature. I tested this hypothesis on seven rocky intertidal invertebrate species by measuring the relative temperature scaling of their metabolic and ingestion rates as well as consumer interaction strength under lab conditions. Energetic efficiencies of these rocky intertidal invertebrates declined and species interaction strengths tended to increase with temperature. Thus, in the rocky intertidal, the mechanistic effect of temperature would be to lower community stability at higher temperatures. Chapter 4 tests if the mechanistic effects of temperature on ingestion rates and species interaction strengths seen in the lab are apparent under field conditions. Bruce Menge and I related bio-mimetic estimates of body temperatures to estimates of per capita mussel ingestion rates and species interaction strengths by the ochre sea star Pisaster ochraceus, a keystone predator of the rocky intertidal. We found a strong, positive effect of body temperature on both per capita ingestion rates and interaction strengths. However, the effects of season and the unique way in which P. ochraceus regulates body temperatures were also apparent, leaving room for adaptation and acclimation to partially compensate for the mechanistic constraint of body temperature. Community structure of the rocky intertidal is associated with environmental forcing due to upwelling, which delivers cold, nutrient rich water to the nearshore environment. As upwelling is driven by large-scale atmospheric pressure gradients, climate change has the potential to affect a wide range of significant ecological processes through changes in water temperature. In Chapter 5, my coauthors and I identified long-term trends in the phenology of upwelling events that are consistent with climate change predictions: upwelling events are becoming stronger and longer. As expected, longer upwelling events were related to lower average water temperatures in the rocky intertidal. Furthermore, recruitment rates of barnacles and mussels were associated with the phenology of upwelling events. Thus climate change is altering the mode and the tempo of environmental forcing in nearshore ecosystems, with ramifications for community structure and function. Ongoing, long-term changes in environmental forcing in rocky intertidal ecosystems provide an opportunity to understand how temperature shapes community structure and the ramifications of climate change. My dissertation research demonstrates that the effect of temperature on organismal performance is an important force structuring ecological communities and has potential as a tractable framework for predicting the community level effects of climate change. Close

• 32. [Article] Cone and seed insects and their impact on whitebark pine

  Whitebark pine, Pinus albicaulis Engelm. is an important but declining high-elevation tree species in western forests. Regeneration of this species has been difficult and the impact of cone and seed insects ...

  Citation × Citation Citation Abstract Copy Title: Cone and seed insects and their impact on whitebark pine Author: United States. Forest Service. Northern Region, Kegley, Sandy, United States. Forest Health Protection Whitebark pine, Pinus albicaulis Engelm. is an important but declining high-elevation tree species in western forests. Regeneration of this species has been difficult and the impact of cone and seed insects unknown. Seven sites selected from the geographical range of whitebark pine in Idaho, Montana, Washington, Oregon, and California were examined for cone and seed insects and their impact. Ten different insect species were found affecting various reproductive structures of whitebark pine. Insects having the greatest impact across most sites were fir coneworm (Dioryctria abietivorella (Grote)) and western conifer seed bug (Leptoglossus occidentalis Heidemann). Coneworms infested up to 68% of cones collected, destroying up to 13% of the seed extracted. Seed bugs damaged up to 27% of the seeds. Pheromone traps for the ponderosa pine cone beetle (Conophthorus ponderosae Hopkins) and coneworms were tested. Ponderosa pine cone beetles were trapped at three of seven sites. Coneworms were trapped at two sites where pheromone traps were deployed. Further studies incorporating different cone crop levels of whitebark pine and other associated tree species are needed to fully determine the effect of cone and seed insects on whitebark pine seed and reproduction. Title: Cone and seed insects and their impact on whitebark pine Author: United States. Forest Service. Northern Region, Kegley, Sandy, United States. Forest Health Protection Whitebark pine, Pinus albicaulis Engelm. is an important but declining high-elevation tree species in western forests. Regeneration of this species has been difficult and the impact of cone and seed insects unknown. Seven sites selected from the geographical range of whitebark pine in Idaho, Montana, Washington, Oregon, and California were examined for cone and seed insects and their impact. Ten different insect species were found affecting various reproductive structures of whitebark pine. Insects having the greatest impact across most sites were fir coneworm (Dioryctria abietivorella (Grote)) and western conifer seed bug (Leptoglossus occidentalis Heidemann). Coneworms infested up to 68% of cones collected, destroying up to 13% of the seed extracted. Seed bugs damaged up to 27% of the seeds. Pheromone traps for the ponderosa pine cone beetle (Conophthorus ponderosae Hopkins) and coneworms were tested. Ponderosa pine cone beetles were trapped at three of seven sites. Coneworms were trapped at two sites where pheromone traps were deployed. Further studies incorporating different cone crop levels of whitebark pine and other associated tree species are needed to fully determine the effect of cone and seed insects on whitebark pine seed and reproduction. Close

• 33. [Article] Twenty-year changes in riparian bird communities of east-central Oregon

  Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing ...

  Citation × Citation Citation Abstract Copy Title: Twenty-year changes in riparian bird communities of east-central Oregon Author: Ellis, Michael S. Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing interest in exploring avian-habitat relationships in these systems to better inform land management, few studies have attempted to describe temporal changes in the region's riparian bird communities. To provide a frame of reference for these changes, we compared indices of avian abundance and diversity from three streamside vegetation associations in east-central Oregon during the 2014 breeding season with baseline data collected by TA Sanders and WD Edge in 1993 and 1994 (Sanders and Edge 1998). Our objectives were to identify patterns of change in the avian community with a focus on riparian shrub-dependent species, to re-examine previously reported relationships between avian abundance and vegetation volume, and to identify possible causes of declines in abundance and diversity with the goal of providing land managers in the semi-arid region information to be used in the guidance and adaptation of management practices. We combined field protocols used by Sanders and Edge to survey birds along point count transects and to measure riparian vegetation with modern analytical techniques. We found few major differences in overall diversity between study periods, but documented precipitous declines in detections for two of three riparian shrub-dependent focal species - Yellow Warbler (Setophaga petechia) and Willow Flycatcher (Empidonax trailii). Song Sparrow (Melospiza melodia) detections declined by a smaller margin. Changes in number of detections for these species did not reflect trends in mesic shrub volume, which had been identified as a likely driver of obligate species abundance by Sanders and Edge but remained relatively unchanged between study periods. Declines of all three focal species reflected regional Breeding Bird Survey trends, corroborating our finding that their declines may not be a result of changes in local site conditions. Compositional similarity between avian communities was significantly higher in 2014 than in 1993-1994, exhibiting a shift toward greater homogenization between structurally distinct riparian habitats. Our results suggest managing working lands for riparian shrub cover or volume, an important metric of grazing intensity and riparian system health, may not be enough to conserve diversity and abundance of riparian-shrub dependent birds, and more work should be done to identify and alleviate factors contributing to these species' declines. Title: Twenty-year changes in riparian bird communities of east-central Oregon Author: Ellis, Michael S. Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing interest in exploring avian-habitat relationships in these systems to better inform land management, few studies have attempted to describe temporal changes in the region's riparian bird communities. To provide a frame of reference for these changes, we compared indices of avian abundance and diversity from three streamside vegetation associations in east-central Oregon during the 2014 breeding season with baseline data collected by TA Sanders and WD Edge in 1993 and 1994 (Sanders and Edge 1998). Our objectives were to identify patterns of change in the avian community with a focus on riparian shrub-dependent species, to re-examine previously reported relationships between avian abundance and vegetation volume, and to identify possible causes of declines in abundance and diversity with the goal of providing land managers in the semi-arid region information to be used in the guidance and adaptation of management practices. We combined field protocols used by Sanders and Edge to survey birds along point count transects and to measure riparian vegetation with modern analytical techniques. We found few major differences in overall diversity between study periods, but documented precipitous declines in detections for two of three riparian shrub-dependent focal species - Yellow Warbler (Setophaga petechia) and Willow Flycatcher (Empidonax trailii). Song Sparrow (Melospiza melodia) detections declined by a smaller margin. Changes in number of detections for these species did not reflect trends in mesic shrub volume, which had been identified as a likely driver of obligate species abundance by Sanders and Edge but remained relatively unchanged between study periods. Declines of all three focal species reflected regional Breeding Bird Survey trends, corroborating our finding that their declines may not be a result of changes in local site conditions. Compositional similarity between avian communities was significantly higher in 2014 than in 1993-1994, exhibiting a shift toward greater homogenization between structurally distinct riparian habitats. Our results suggest managing working lands for riparian shrub cover or volume, an important metric of grazing intensity and riparian system health, may not be enough to conserve diversity and abundance of riparian-shrub dependent birds, and more work should be done to identify and alleviate factors contributing to these species' declines. Close

• 34. [Article] Seed and establishment limitation contribute to long-term native forb declines in California grasslands

  This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/.

  Citation × Citation Citation Abstract Copy Title: Seed and establishment limitation contribute to long-term native forb declines in California grasslands Author: Brandt, Angela J., Seabloom, Eric W. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/. Title: Seed and establishment limitation contribute to long-term native forb declines in California grasslands Author: Brandt, Angela J., Seabloom, Eric W. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/. Close

• 35. [Article] Agricultural impacts on amphibian survival, growth, and distributions

  The potential impact of chemical contaminants and conservation practices on amphibians in agricultural landscapes is a key research topic globally. Amphibians represent a common group in many freshwater ...

  Citation × Citation Citation Abstract Copy Title: Agricultural impacts on amphibian survival, growth, and distributions Author: Baker, Nick J. The potential impact of chemical contaminants and conservation practices on amphibians in agricultural landscapes is a key research topic globally. Amphibians represent a common group in many freshwater systems and are currently experiencing worldwide population declines. Global amphibian declines may be attributed to a number of causes, including habitat loss, introduced species, global climate change, disease, and chemical contaminants; most species declines are not a function of only one factor, but a result of interacting factors and synergistic impacts. I analyzed the impact of field conservation efforts employed in the Calapooia watershed, located in the central Willamette Valley in Oregon, on amphibian species diversity using Simpson's Diversity Index. In the Calapooia watershed the value of this index increased when conservation efforts, such as retaining crop residue and riparian buffers, were present. This suggests that species diversity increased with increased conservation effort at the field level. In addition, I found species-specific habitat associations in the Calapooia watershed. Long-toed salamanders (Ambystoma macrodactylum) were associated with stream channel cover. Rough-skinned newts (Taricha granulosa) and Red-legged frogs (Rana aurora) showed similar relationships to pH, bank width, depth, and riparian habitat where as Pacific treefrogs (Pseudacris regilla) showed strong relationships to increased structural heterogeneity, increased distance to nearest agricultural field, and increased human disturbance. These results indicate that conservation efforts can impact amphibian biodiversity, and that there are species-specific habitat associations in the Calapooia watershed. My third chapter looked at pesticides and fertilizers, which have been shown to negatively affect many species of amphibians. I used meta-analytic techniques to quantify the lethal and sub-lethal effects of pesticides and fertilizers on amphibians in an effort to review the published work to date. I found that, in general, pesticides and fertilizers negatively affect amphibians by reducing both survival and growth. Pesticide and fertilizer chemical classes showed differences in their impacts on amphibians: inorganic fertilizers, organophosphates, phosphonoglycines, and triazines negatively affected amphibian survival, while, organophosphates and triazines negatively affected amphibian growth. Title: Agricultural impacts on amphibian survival, growth, and distributions Author: Baker, Nick J. The potential impact of chemical contaminants and conservation practices on amphibians in agricultural landscapes is a key research topic globally. Amphibians represent a common group in many freshwater systems and are currently experiencing worldwide population declines. Global amphibian declines may be attributed to a number of causes, including habitat loss, introduced species, global climate change, disease, and chemical contaminants; most species declines are not a function of only one factor, but a result of interacting factors and synergistic impacts. I analyzed the impact of field conservation efforts employed in the Calapooia watershed, located in the central Willamette Valley in Oregon, on amphibian species diversity using Simpson's Diversity Index. In the Calapooia watershed the value of this index increased when conservation efforts, such as retaining crop residue and riparian buffers, were present. This suggests that species diversity increased with increased conservation effort at the field level. In addition, I found species-specific habitat associations in the Calapooia watershed. Long-toed salamanders (Ambystoma macrodactylum) were associated with stream channel cover. Rough-skinned newts (Taricha granulosa) and Red-legged frogs (Rana aurora) showed similar relationships to pH, bank width, depth, and riparian habitat where as Pacific treefrogs (Pseudacris regilla) showed strong relationships to increased structural heterogeneity, increased distance to nearest agricultural field, and increased human disturbance. These results indicate that conservation efforts can impact amphibian biodiversity, and that there are species-specific habitat associations in the Calapooia watershed. My third chapter looked at pesticides and fertilizers, which have been shown to negatively affect many species of amphibians. I used meta-analytic techniques to quantify the lethal and sub-lethal effects of pesticides and fertilizers on amphibians in an effort to review the published work to date. I found that, in general, pesticides and fertilizers negatively affect amphibians by reducing both survival and growth. Pesticide and fertilizer chemical classes showed differences in their impacts on amphibians: inorganic fertilizers, organophosphates, phosphonoglycines, and triazines negatively affected amphibian survival, while, organophosphates and triazines negatively affected amphibian growth. Close

• 36. [Article] Island survivors: population genetic structure and demography of the critically endangered giant lizard of La Gomera, Gallotia bravoana

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by BioMed Central Ltd. The published article can be found at: http://www.biomedcentral.com/bmcgene...

  Citation × Citation Citation Abstract Copy Title: Island survivors: population genetic structure and demography of the critically endangered giant lizard of La Gomera, Gallotia bravoana Author: Cerón-Souza, Ivania, Mateo, José A., Zardoya, Rafael, Gonzalez, Elena G. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by BioMed Central Ltd. The published article can be found at: http://www.biomedcentral.com/bmcgenet/. Title: Island survivors: population genetic structure and demography of the critically endangered giant lizard of La Gomera, Gallotia bravoana Author: Cerón-Souza, Ivania, Mateo, José A., Zardoya, Rafael, Gonzalez, Elena G. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by BioMed Central Ltd. The published article can be found at: http://www.biomedcentral.com/bmcgenet/. Close

• 37. [Article] Heart rate, survivorship, oxygen consumption, and metabolic end product accumulations in the intertidal limpets Collisella pelta and Collisella digitalis in relation to desiccation and hypoxia

  The heart rate, oxygen consumption, survivorship, and 1-lactate accumulation were determined in the intertidal limpets Collisella pelta and Collisella digitalis in relation to laboratory desiccation at ...

  Citation × Citation Citation Abstract Copy Title: Heart rate, survivorship, oxygen consumption, and metabolic end product accumulations in the intertidal limpets Collisella pelta and Collisella digitalis in relation to desiccation and hypoxia Author: Boese, Bruce Leon The heart rate, oxygen consumption, survivorship, and 1-lactate accumulation were determined in the intertidal limpets Collisella pelta and Collisella digitalis in relation to laboratory desiccation at 15°C or 30°C. Water loss was computed as a percentage of total initial body water (wet weight - dry weight). Although water was lost faster in C. digitalis than in C. pelta, C. digitalis tolerated more water loss and survived longer than C. pelta at both experimental temperatures. During the first few hours of desiccation at 15°C the heart rate of C. digitalis was constant while in C. pelta the heart rate declined rapidly. During desiccation at 30°C the heart rates of both species declined rapidly. No change was noted in control heart rates, determined under moist aerial conditions, in either species during a 40 hour exposure period. Oxygen consumption of C. digitalis declined gradually during desiccation at 15°C to about 60% of the undesiccated aerial control rate after 46 hours of exposure. During desiccation at 30°C the decline in oxygen consumption was much more pronounced. In C. pelta during desiccation at 15°C oxygen consumption progressively declined with increasing length of exposure to approximately 50% of control rates for the first 16 hours of exposure at which time rates became constant. At 30°C a more pronounced reduction in oxygen consumption occurred. Whole-body lactate accumulated in both species during desiccation at 15°C and 30°C in comparison with controls. At 15°C accumulation in C. pelta began after 15 hours of desiccation while at 30°C accumulations were evident after 4 hours. In contrast, C. digitalis gradually accumulated lactate during the entire length of exposure to desiccation conditions at 15°C. Upon exposure to moist nitrogen atmosphere both species exhibited a rapid bradycardia. Heart rates recovered rapidly after exposure and overshot pre-exposure rates indicating oxygen debt repayment. Of the three anaerobic end products examined (alanine, succinate and lactate) only lactate accumulated to any degree in either species during anoxia. During anoxia C. digitalis accumulated more lactate than C. pelta. C. pelta reached a maximum accumulation after 4 hours of anoxia while C. digitalis continued to accumulate lactate over the entire length of exposure to moist nitrogen. The results suggest differences between C. digitalis and C. pelta in metabolic adaptations which may be related to intertidal zonational differences. Title: Heart rate, survivorship, oxygen consumption, and metabolic end product accumulations in the intertidal limpets Collisella pelta and Collisella digitalis in relation to desiccation and hypoxia Author: Boese, Bruce Leon The heart rate, oxygen consumption, survivorship, and 1-lactate accumulation were determined in the intertidal limpets Collisella pelta and Collisella digitalis in relation to laboratory desiccation at 15°C or 30°C. Water loss was computed as a percentage of total initial body water (wet weight - dry weight). Although water was lost faster in C. digitalis than in C. pelta, C. digitalis tolerated more water loss and survived longer than C. pelta at both experimental temperatures. During the first few hours of desiccation at 15°C the heart rate of C. digitalis was constant while in C. pelta the heart rate declined rapidly. During desiccation at 30°C the heart rates of both species declined rapidly. No change was noted in control heart rates, determined under moist aerial conditions, in either species during a 40 hour exposure period. Oxygen consumption of C. digitalis declined gradually during desiccation at 15°C to about 60% of the undesiccated aerial control rate after 46 hours of exposure. During desiccation at 30°C the decline in oxygen consumption was much more pronounced. In C. pelta during desiccation at 15°C oxygen consumption progressively declined with increasing length of exposure to approximately 50% of control rates for the first 16 hours of exposure at which time rates became constant. At 30°C a more pronounced reduction in oxygen consumption occurred. Whole-body lactate accumulated in both species during desiccation at 15°C and 30°C in comparison with controls. At 15°C accumulation in C. pelta began after 15 hours of desiccation while at 30°C accumulations were evident after 4 hours. In contrast, C. digitalis gradually accumulated lactate during the entire length of exposure to desiccation conditions at 15°C. Upon exposure to moist nitrogen atmosphere both species exhibited a rapid bradycardia. Heart rates recovered rapidly after exposure and overshot pre-exposure rates indicating oxygen debt repayment. Of the three anaerobic end products examined (alanine, succinate and lactate) only lactate accumulated to any degree in either species during anoxia. During anoxia C. digitalis accumulated more lactate than C. pelta. C. pelta reached a maximum accumulation after 4 hours of anoxia while C. digitalis continued to accumulate lactate over the entire length of exposure to moist nitrogen. The results suggest differences between C. digitalis and C. pelta in metabolic adaptations which may be related to intertidal zonational differences. Close

• 38. [Article] An analysis of the population dynamics of selected avian species

  The impact that pesticides may have had on the mortality rates and productivity rates of non-game birds during the last 25 years was evaluated by studying the population dynamics of 16 species. A mathematical ...

  Citation × Citation Citation Abstract Copy Title: An analysis of the population dynamics of selected avian species Author: Henny, Charles J. The impact that pesticides may have had on the mortality rates and productivity rates of non-game birds during the last 25 years was evaluated by studying the population dynamics of 16 species. A mathematical model showing the relationships between population parameters that yielded stable populations was developed. The information needed for the model included: (1) mortality rate schedule (obtained from recoveries of banded birds), (2) productivity rates, and (3) the age of sexual maturity. Production requirements for a stable population and annual rate of change (increase or decrease) in population levels were estimated. Population parameters were compared to determine if changes had occurred between time periods (i.e, 1925-1945 vs. 1946-1965). The great horned owl, red-shouldered hawk, sparrow hawk, osprey, barn owl, Cooper's hawk, red-tailed hawk, great blue heron, black-crowned night heron, brown pelican, barn owl, chimney swift, blue jay, black-capped chickadee, cardinal, and robin were subjected to this analysis. No increase in post-fledging mortality rates in any of the species has occurred since 1945. Therefore, accelerated decline in the species studied must have resulted from lowered reproductive rates. Mortality rates have decreased in the Cooper's hawk, sparrow hawk, great blue heron, and brown pelican. A decrease in shooting pressure was associated with decreased mortality rates. Evidence of declining reproductive rates were found in the brown pelican, osprey, Cooper's hawk, red-shouldered hawk, and sparrow hawk. No changes in reproductive rates were noted in the red-tailed hawk, great horned owl, or barn owl. Information on productivity rates was not available for comparison with the other species although rates of productivity essential for a stable population were estimated. This work will provide the basis for making comparisons in future studies. No change in reproductive rates was apparent among species feeding primarily on mammals. Species exhibiting a lowered reproductive success since 1945 were those whose major food items consisted of fish, reptiles, amphibians, or birds. Lowered reproductive success was accompanied by a decrease in eggshell thickness. Other investigators have reported that sparrow hawks and mallard ducks fed a diet of DDE and dieldrin have produced thin eggshells under laboratory conditions, and exhibited a lower reproductive success. Many bird species which consume food in which chlorinated hydrocarbon pesticides have been concentrated through a series of transfers along food chains have declined. The chlorinated hydrocarbon pesticides are believed responsible. Title: An analysis of the population dynamics of selected avian species Author: Henny, Charles J. The impact that pesticides may have had on the mortality rates and productivity rates of non-game birds during the last 25 years was evaluated by studying the population dynamics of 16 species. A mathematical model showing the relationships between population parameters that yielded stable populations was developed. The information needed for the model included: (1) mortality rate schedule (obtained from recoveries of banded birds), (2) productivity rates, and (3) the age of sexual maturity. Production requirements for a stable population and annual rate of change (increase or decrease) in population levels were estimated. Population parameters were compared to determine if changes had occurred between time periods (i.e, 1925-1945 vs. 1946-1965). The great horned owl, red-shouldered hawk, sparrow hawk, osprey, barn owl, Cooper's hawk, red-tailed hawk, great blue heron, black-crowned night heron, brown pelican, barn owl, chimney swift, blue jay, black-capped chickadee, cardinal, and robin were subjected to this analysis. No increase in post-fledging mortality rates in any of the species has occurred since 1945. Therefore, accelerated decline in the species studied must have resulted from lowered reproductive rates. Mortality rates have decreased in the Cooper's hawk, sparrow hawk, great blue heron, and brown pelican. A decrease in shooting pressure was associated with decreased mortality rates. Evidence of declining reproductive rates were found in the brown pelican, osprey, Cooper's hawk, red-shouldered hawk, and sparrow hawk. No changes in reproductive rates were noted in the red-tailed hawk, great horned owl, or barn owl. Information on productivity rates was not available for comparison with the other species although rates of productivity essential for a stable population were estimated. This work will provide the basis for making comparisons in future studies. No change in reproductive rates was apparent among species feeding primarily on mammals. Species exhibiting a lowered reproductive success since 1945 were those whose major food items consisted of fish, reptiles, amphibians, or birds. Lowered reproductive success was accompanied by a decrease in eggshell thickness. Other investigators have reported that sparrow hawks and mallard ducks fed a diet of DDE and dieldrin have produced thin eggshells under laboratory conditions, and exhibited a lower reproductive success. Many bird species which consume food in which chlorinated hydrocarbon pesticides have been concentrated through a series of transfers along food chains have declined. The chlorinated hydrocarbon pesticides are believed responsible. Close

• 39. [Article] Riparian bird communities in Portland, Oregon : habitat, urbanization, and spatial scale patterns

  Urban ecosystems are characterized by human disturbance and changes in the amount, types, and spatial arrangement of wildlife habitat. The relative importance of habitat and human associated variables ...

  Citation × Citation Citation Abstract Copy Title: Riparian bird communities in Portland, Oregon : habitat, urbanization, and spatial scale patterns Author: Hennings, Lori A. Urban ecosystems are characterized by human disturbance and changes in the amount, types, and spatial arrangement of wildlife habitat. The relative importance of habitat and human associated variables to urban birds is unknown. In 1999, I surveyed spring bird and plant communities along 54 perennial streams in the Portland, Oregon metropolitan region. My objectives were to determine (1) what habitat and human-associated variables were related to avian community measures, (2) how far from riparian areas did relationships between avifauna and canopy cover and development extend, and (3) habitat characteristics associated with individual bird species. I used Principal Components Analysis to cluster and reduce the number of explanatory variables, and regressed bird community variables against the resulting principal components. Total and nonnative bird abundance were negatively related to the first principal component, PC 1 (high-scoring PC 1 sites had wide, structurally complex native forests) (r2 = 0.38, P < 0.0001 and r2 = 0.63, P < 0.0001, respectively). Several weak (r2 = 0.17-0.31, P < 0.003) curvilinear relationships emerged between overall and native species richness and diversity versus PC 1. Neotropical migratory bird (NMB) species richness and diversity were negatively related to human development variables, and positively related to native shrubs (adjusted r2 = 0.21 and 0.18, respectively; P < 0.003). I regressed bird community variables against canopy cover and street density for each of ten 50-m buffers around sites, then plotted the model fit (r) against buffer width. Native and nonnative abundance measures were negatively related to canopy cover. Total abundance was best predicted by canopy cover 300-350 m from the stream whereas normative abundance was predicted nearly equally by canopy cover in each buffer. The relationships between total species richness, native species richness, total diversity and native diversity were curvilinearly related to canopy cover, with canopy in the first 50 m appearing most important. Neotropical migratory bird species richness, diversity and abundance were negatively related to street density within 150 m of the stream. Brown-headed Cowbird (Molothrus ater) abundance was increasingly, negatively related to canopy cover as spatial scale increased. I used logistic regression to identify habitat and/or human-associated variables that predicted the occurrence of 32 species. The occurrence of four species (American Crow [Corvus brachyrhynchos], House Finch [Carpodacus mexicanus], Red-breasted Nuthatch [Sitta canadensis], and Vaux's Swift [Chaetura vauxi]) was positively, and five species (Black-headed Grosbeak [Pheucticus melanocephalus], Common Yellowthroat [Geothlypis trichas], Rufous Hummingbird [Selasphorus rufus], Steller's Jay [Cyanocitta setlleri], and Swainson's Thrush [Catharus ustulatus]) negatively related to human-associated variables. My results suggest that increasing urban canopy cover is the most valuable land management action for many breeding bird species. Preserving large undeveloped habitats and controlling urban sprawl may help prevent regional declines of NMB species. Title: Riparian bird communities in Portland, Oregon : habitat, urbanization, and spatial scale patterns Author: Hennings, Lori A. Urban ecosystems are characterized by human disturbance and changes in the amount, types, and spatial arrangement of wildlife habitat. The relative importance of habitat and human associated variables to urban birds is unknown. In 1999, I surveyed spring bird and plant communities along 54 perennial streams in the Portland, Oregon metropolitan region. My objectives were to determine (1) what habitat and human-associated variables were related to avian community measures, (2) how far from riparian areas did relationships between avifauna and canopy cover and development extend, and (3) habitat characteristics associated with individual bird species. I used Principal Components Analysis to cluster and reduce the number of explanatory variables, and regressed bird community variables against the resulting principal components. Total and nonnative bird abundance were negatively related to the first principal component, PC 1 (high-scoring PC 1 sites had wide, structurally complex native forests) (r2 = 0.38, P < 0.0001 and r2 = 0.63, P < 0.0001, respectively). Several weak (r2 = 0.17-0.31, P < 0.003) curvilinear relationships emerged between overall and native species richness and diversity versus PC 1. Neotropical migratory bird (NMB) species richness and diversity were negatively related to human development variables, and positively related to native shrubs (adjusted r2 = 0.21 and 0.18, respectively; P < 0.003). I regressed bird community variables against canopy cover and street density for each of ten 50-m buffers around sites, then plotted the model fit (r) against buffer width. Native and nonnative abundance measures were negatively related to canopy cover. Total abundance was best predicted by canopy cover 300-350 m from the stream whereas normative abundance was predicted nearly equally by canopy cover in each buffer. The relationships between total species richness, native species richness, total diversity and native diversity were curvilinearly related to canopy cover, with canopy in the first 50 m appearing most important. Neotropical migratory bird species richness, diversity and abundance were negatively related to street density within 150 m of the stream. Brown-headed Cowbird (Molothrus ater) abundance was increasingly, negatively related to canopy cover as spatial scale increased. I used logistic regression to identify habitat and/or human-associated variables that predicted the occurrence of 32 species. The occurrence of four species (American Crow [Corvus brachyrhynchos], House Finch [Carpodacus mexicanus], Red-breasted Nuthatch [Sitta canadensis], and Vaux's Swift [Chaetura vauxi]) was positively, and five species (Black-headed Grosbeak [Pheucticus melanocephalus], Common Yellowthroat [Geothlypis trichas], Rufous Hummingbird [Selasphorus rufus], Steller's Jay [Cyanocitta setlleri], and Swainson's Thrush [Catharus ustulatus]) negatively related to human-associated variables. My results suggest that increasing urban canopy cover is the most valuable land management action for many breeding bird species. Preserving large undeveloped habitats and controlling urban sprawl may help prevent regional declines of NMB species. Close

• 40. [Article] Using remote sensing, in situ observations, and geographic information systems to map benthic habitats at Heceta Bank, Oregon

  Dramatic declines in many species of demersal fishes off the West Coast have resulted in the designation of nine commercially important species as being overfished. While the causes of those declines are ...

  Citation × Citation Citation Abstract Copy Title: Using remote sensing, in situ observations, and geographic information systems to map benthic habitats at Heceta Bank, Oregon Author: Whitmire, Curt E. Dramatic declines in many species of demersal fishes off the West Coast have resulted in the designation of nine commercially important species as being overfished. While the causes of those declines are not clearly understood, the fact remains that a paucity of life history and abundance data exists for many demersal species, also known as groundfish. Due to this uncertainty, only 21 of the 82 species of groundfish managed under the Groundfish Fishery Management Plan of the Pacific Fishery Management Council (PFMC) have been fully assessed. One challenge in designing a systematic survey of groundfish resources is that many species associate with heterogeneous substrate of varying relief. In many areas, the rugosity of the substrata precludes sampling by conventional techniques (e.g. bottom trawl gear). This has stimulated research that characterizes fish-habitat associations for use in design of new survey methodology. Using a combination of remote sensing, in situ observations, and spatial analytical techniques, four benthic habitat classes were mapped for a large rocky bank off the central Oregon coast known as Heceta Bank. Observational data from human-occupied submersible and remotely operated vehicle dives in the late 1980s, 2000 and 2001 were used to establish habitat classes with specific substrate characteristics that have been statistically shown to correlate with demersal fish distributions. The observational habitat data was then extrapolated over the extent of a multibeam sonar survey conducted in 1998 using quantitative parameters derived from high-resolution bathymetric and backscatter imagery of the seafloor. The resultant map predicts the locations of four habitat classes: Ridge-Gully, High-Relief Rock (boulders, cobbles), Unconsolidated Sediment 1 (muds), and Unconsolidated Sediment 2 (sands). The main utility of the habitat map developed as part of the current study is that it provides a context for analyses of a variety of spatial data. For instance, habitat data provides one additional spatial component besides depth and latitude that can be used to stratify catch per unit effort data from surveys and commercial logbooks. Also, essential fish habitat for many demersal species can now be identified in more detail. Finally, habitat data like those presented here can aid in the design of marine reserves and protected areas by providing a context for spatial analyses of data of ecological importance. Title: Using remote sensing, in situ observations, and geographic information systems to map benthic habitats at Heceta Bank, Oregon Author: Whitmire, Curt E. Dramatic declines in many species of demersal fishes off the West Coast have resulted in the designation of nine commercially important species as being overfished. While the causes of those declines are not clearly understood, the fact remains that a paucity of life history and abundance data exists for many demersal species, also known as groundfish. Due to this uncertainty, only 21 of the 82 species of groundfish managed under the Groundfish Fishery Management Plan of the Pacific Fishery Management Council (PFMC) have been fully assessed. One challenge in designing a systematic survey of groundfish resources is that many species associate with heterogeneous substrate of varying relief. In many areas, the rugosity of the substrata precludes sampling by conventional techniques (e.g. bottom trawl gear). This has stimulated research that characterizes fish-habitat associations for use in design of new survey methodology. Using a combination of remote sensing, in situ observations, and spatial analytical techniques, four benthic habitat classes were mapped for a large rocky bank off the central Oregon coast known as Heceta Bank. Observational data from human-occupied submersible and remotely operated vehicle dives in the late 1980s, 2000 and 2001 were used to establish habitat classes with specific substrate characteristics that have been statistically shown to correlate with demersal fish distributions. The observational habitat data was then extrapolated over the extent of a multibeam sonar survey conducted in 1998 using quantitative parameters derived from high-resolution bathymetric and backscatter imagery of the seafloor. The resultant map predicts the locations of four habitat classes: Ridge-Gully, High-Relief Rock (boulders, cobbles), Unconsolidated Sediment 1 (muds), and Unconsolidated Sediment 2 (sands). The main utility of the habitat map developed as part of the current study is that it provides a context for analyses of a variety of spatial data. For instance, habitat data provides one additional spatial component besides depth and latitude that can be used to stratify catch per unit effort data from surveys and commercial logbooks. Also, essential fish habitat for many demersal species can now be identified in more detail. Finally, habitat data like those presented here can aid in the design of marine reserves and protected areas by providing a context for spatial analyses of data of ecological importance. Close