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• 1. [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

• 2. [Article] A comparison of mechanisms generating vertical transport in the Brazilian coastal upwelling regions

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9291.

  Citation × Citation Citation Abstract Copy Title: A comparison of mechanisms generating vertical transport in the Brazilian coastal upwelling regions Author: Mazzini, P. L. F., Barth, John A. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9291. Title: A comparison of mechanisms generating vertical transport in the Brazilian coastal upwelling regions Author: Mazzini, P. L. F., Barth, John A. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9291. Close

• 3. [Article] Changing Climate, Changing Contexts : Variation in Rocky Intertidal Predator-prey Interactions Seen Through an Environmental Stress Framework

  Citation × Citation Citation Abstract Copy Title: Changing Climate, Changing Contexts : Variation in Rocky Intertidal Predator-prey Interactions Seen Through an Environmental Stress Framework Author: Cerny-Chipman, Elizabeth B. Title: Changing Climate, Changing Contexts : Variation in Rocky Intertidal Predator-prey Interactions Seen Through an Environmental Stress Framework Author: Cerny-Chipman, Elizabeth B. Close

• 4. [Article] Coastal Atmospheric Circulation around an Idealized Cape during Wind-Driven Upwelling Studied from a Coupled Ocean–Atmosphere Model

  The study analyzes atmospheric circulation around an idealized coastal cape during summertime upwelling-favorable wind conditions simulated by a mesoscale coupled ocean–atmosphere model. The domain resembles ...

  Citation × Citation Citation Abstract Copy Title: Coastal Atmospheric Circulation around an Idealized Cape during Wind-Driven Upwelling Studied from a Coupled Ocean–Atmosphere Model Author: Skyllingstad, Eric D., Samelson, Roger M., Perlin, Natalie The study analyzes atmospheric circulation around an idealized coastal cape during summertime upwelling-favorable wind conditions simulated by a mesoscale coupled ocean–atmosphere model. The domain resembles an eastern ocean boundary with a single cape protruding into the ocean in the center of a coastline. The model predicts the formation of an orographic wind intensification area on the lee side of the cape, extending a few hundred kilometers downstream and seaward. Imposed initial conditions do not contain a low-level temperature inversion, which nevertheless forms on the lee side of the cape during the simulation, and which is accompanied by high Froude numbers diagnosed in that area, suggesting the presence of the supercritical flow. Formation of such an inversion is likely caused by average easterly winds resulting on the lee side that bring warm air masses originating over land, as well as by air warming during adiabatic descent on the lee side of the topographic obstacle. Mountain leeside dynamics modulated by differential diurnal heating is thus suggested to dominate the wind regime in the studied case. The location of this wind feature and its strong diurnal variations correlate well with the development and evolution of the localized lee side trough over the coastal ocean. The vertical extent of the leeside trough is limited by the subsidence inversion aloft. Diurnal modulations of the ocean sea surface temperatures (SSTs) and surface depth-averaged ocean current on the lee side of the cape are found to strongly correlate with wind stress variations over the same area. Wind-driven coastal upwelling develops during the simulation and extends offshore about 50 km upwind of the cape. It widens twice as much on the lee side of the cape, where the coldest nearshore SSTs are found. The average wind stress–SST coupling in the 100-km coastal zone is strong for the region upwind of the cape, but is notably weaker for the downwind region, estimated from the 10-day-average fields. The study findings demonstrate that orographic and diurnal modulations of the near-surface atmospheric flow on the lee side of the cape notably affect the air–sea coupling on various temporal scales: weaker wind stress–SST coupling results for the long-term averages, while strong correlations are found on the diurnal scale. Title: Coastal Atmospheric Circulation around an Idealized Cape during Wind-Driven Upwelling Studied from a Coupled Ocean–Atmosphere Model Author: Skyllingstad, Eric D., Samelson, Roger M., Perlin, Natalie The study analyzes atmospheric circulation around an idealized coastal cape during summertime upwelling-favorable wind conditions simulated by a mesoscale coupled ocean–atmosphere model. The domain resembles an eastern ocean boundary with a single cape protruding into the ocean in the center of a coastline. The model predicts the formation of an orographic wind intensification area on the lee side of the cape, extending a few hundred kilometers downstream and seaward. Imposed initial conditions do not contain a low-level temperature inversion, which nevertheless forms on the lee side of the cape during the simulation, and which is accompanied by high Froude numbers diagnosed in that area, suggesting the presence of the supercritical flow. Formation of such an inversion is likely caused by average easterly winds resulting on the lee side that bring warm air masses originating over land, as well as by air warming during adiabatic descent on the lee side of the topographic obstacle. Mountain leeside dynamics modulated by differential diurnal heating is thus suggested to dominate the wind regime in the studied case. The location of this wind feature and its strong diurnal variations correlate well with the development and evolution of the localized lee side trough over the coastal ocean. The vertical extent of the leeside trough is limited by the subsidence inversion aloft. Diurnal modulations of the ocean sea surface temperatures (SSTs) and surface depth-averaged ocean current on the lee side of the cape are found to strongly correlate with wind stress variations over the same area. Wind-driven coastal upwelling develops during the simulation and extends offshore about 50 km upwind of the cape. It widens twice as much on the lee side of the cape, where the coldest nearshore SSTs are found. The average wind stress–SST coupling in the 100-km coastal zone is strong for the region upwind of the cape, but is notably weaker for the downwind region, estimated from the 10-day-average fields. The study findings demonstrate that orographic and diurnal modulations of the near-surface atmospheric flow on the lee side of the cape notably affect the air–sea coupling on various temporal scales: weaker wind stress–SST coupling results for the long-term averages, while strong correlations are found on the diurnal scale. Close

• 5. [Article] Seasonal Cycle of Phytoplankton Community Composition in the Coastal Upwelling System Off Central Oregon in 2009

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Springer ...

  Citation × Citation Citation Abstract Copy Title: Seasonal Cycle of Phytoplankton Community Composition in the Coastal Upwelling System Off Central Oregon in 2009 Author: Du, Xiuning, Peterson, William T. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/12237. Title: Seasonal Cycle of Phytoplankton Community Composition in the Coastal Upwelling System Off Central Oregon in 2009 Author: Du, Xiuning, Peterson, William T. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/12237. Close

• 6. [Article] Large medusae in surface waters of the Northern California Current: variability in relation to environmental conditions

  This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://www.springerlink.com/content/0018-8158/. To the best of our knowledge, one or more authors ...

  Citation × Citation Citation Abstract Copy Title: Large medusae in surface waters of the Northern California Current: variability in relation to environmental conditions Author: Emmett, Robert L., Suchman, Cynthia L., Daly, Elizabeth A., Brodeur, Richard D. This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://www.springerlink.com/content/0018-8158/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Title: Large medusae in surface waters of the Northern California Current: variability in relation to environmental conditions Author: Emmett, Robert L., Suchman, Cynthia L., Daly, Elizabeth A., Brodeur, Richard D. This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://www.springerlink.com/content/0018-8158/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Close

• 7. [Article] The roles of nutrient dynamics, oceanography, and light in the structure and functioning of rocky intertidal macrophyte assemblages

  The influence of the physical environment on organisms has long been a subject of ecological research. But, the complex drivers of environmental variation, and the multiple scales at which this can occur, ...

  Citation × Citation Citation Abstract Copy Title: The roles of nutrient dynamics, oceanography, and light in the structure and functioning of rocky intertidal macrophyte assemblages Author: Close, Sarah L. The influence of the physical environment on organisms has long been a subject of ecological research. But, the complex drivers of environmental variation, and the multiple scales at which this can occur, make studying this topic a difficult challenge. In rocky intertidal habitats, oceanographic- and climate-scale variability influence benthic communities primarily via changes in temperature, propagule delivery, and nutrient availability. Nutrient availability especially is thought to influence the diverse and productive macrophyte assemblages in these communities. While bottom-up regulation of communities provisioned by resource subsidies is known to play a role in community dynamics in this system, we are still developing an understanding of how nutrients influence macrophytes. In this dissertation, I investigated the environmental drivers of intertidal macrophyte ecology at both the biogeographic (regional) and the local scale. Using data spanning 10 years and over 900 km of coastline within the California Current Large Marine Ecosystem (CCLME), I first evaluated the contributions of nutrient availability, upwelling, spatiotemporal variation, and climate variability to macrophyte tissue nutrient content. The insights gained from this investigation show a strong influence of nutrient availability on nutrient status, although that relationship varied among species. I also observed remarkably similar interannual variability in tissue nutrient content, which is consistent with regional and basin-scale oceanographic processes. My results in Chapter 2 point to a role of nutrient availability in modulating macrophyte nutrient content which is consistent with regional forcing in the CCLME. In Chapter 3 I asked how nutrient and light availability drive growth, and how this relates to nutrient content. Combining insights from Chapter 2 on macrophyte nutrient content with data on growth rates in two dominant low intertidal species, Saccharina sessilis and Phyllospadix scouleri, I found contrasting drivers of growth in the two species. Growth in S. sessilis was positively related to nutrient availability, consistent with our expectations, but negatively related to light availability, confounding predictions. Growth in P. scouleri, on the other hand, showed more complicated dynamics in relation to nutrients and light, suggesting that the abundance of these resources modulates the growth response. These patterns nonetheless suggest that growth in these species is strongly influenced by the upwelling process, although the mechanisms behind such influences may vary. Finally, in Chapter 4 I approached the question of how the lower limits of one high zone intertidal species are set, that of Fucus distichus, to determine local scale environmental drivers of macrophyte distribution. Through a field experiment, I manipulated F. distichus across an intertidal gradient and found that it had high mortality at low intertidal elevations. Using a laboratory mesocosm experiment, I found that the mechanism behind the elevational pattern appears to be the reduced light availability in the low intertidal zone. Combined with the insights from Chapter 3, which suggests that light influences macrophyte growth, the result that light could play a role in setting the elevational limit in this species also underscores the importance of considering this resource in studies of macrophyte ecology. Title: The roles of nutrient dynamics, oceanography, and light in the structure and functioning of rocky intertidal macrophyte assemblages Author: Close, Sarah L. The influence of the physical environment on organisms has long been a subject of ecological research. But, the complex drivers of environmental variation, and the multiple scales at which this can occur, make studying this topic a difficult challenge. In rocky intertidal habitats, oceanographic- and climate-scale variability influence benthic communities primarily via changes in temperature, propagule delivery, and nutrient availability. Nutrient availability especially is thought to influence the diverse and productive macrophyte assemblages in these communities. While bottom-up regulation of communities provisioned by resource subsidies is known to play a role in community dynamics in this system, we are still developing an understanding of how nutrients influence macrophytes. In this dissertation, I investigated the environmental drivers of intertidal macrophyte ecology at both the biogeographic (regional) and the local scale. Using data spanning 10 years and over 900 km of coastline within the California Current Large Marine Ecosystem (CCLME), I first evaluated the contributions of nutrient availability, upwelling, spatiotemporal variation, and climate variability to macrophyte tissue nutrient content. The insights gained from this investigation show a strong influence of nutrient availability on nutrient status, although that relationship varied among species. I also observed remarkably similar interannual variability in tissue nutrient content, which is consistent with regional and basin-scale oceanographic processes. My results in Chapter 2 point to a role of nutrient availability in modulating macrophyte nutrient content which is consistent with regional forcing in the CCLME. In Chapter 3 I asked how nutrient and light availability drive growth, and how this relates to nutrient content. Combining insights from Chapter 2 on macrophyte nutrient content with data on growth rates in two dominant low intertidal species, Saccharina sessilis and Phyllospadix scouleri, I found contrasting drivers of growth in the two species. Growth in S. sessilis was positively related to nutrient availability, consistent with our expectations, but negatively related to light availability, confounding predictions. Growth in P. scouleri, on the other hand, showed more complicated dynamics in relation to nutrients and light, suggesting that the abundance of these resources modulates the growth response. These patterns nonetheless suggest that growth in these species is strongly influenced by the upwelling process, although the mechanisms behind such influences may vary. Finally, in Chapter 4 I approached the question of how the lower limits of one high zone intertidal species are set, that of Fucus distichus, to determine local scale environmental drivers of macrophyte distribution. Through a field experiment, I manipulated F. distichus across an intertidal gradient and found that it had high mortality at low intertidal elevations. Using a laboratory mesocosm experiment, I found that the mechanism behind the elevational pattern appears to be the reduced light availability in the low intertidal zone. Combined with the insights from Chapter 3, which suggests that light influences macrophyte growth, the result that light could play a role in setting the elevational limit in this species also underscores the importance of considering this resource in studies of macrophyte ecology. Close

• 8. [Article] Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009 Author: McKibben, S. Morgaine, Du, Xiuning, White, Angelicque E., et al., Peterson, William T., Watkins-Brandt, Katie S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/harmful-algae. Title: Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009 Author: McKibben, S. Morgaine, Du, Xiuning, White, Angelicque E., et al., Peterson, William T., Watkins-Brandt, Katie S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/harmful-algae. Close