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• 1. [Article] Monitoring for stream temperature total maximum daily load development

  Citation × Citation Citation Abstract Copy Title: Monitoring for stream temperature total maximum daily load development Author: Oregon. Dept. of Environmental Quality Title: Monitoring for stream temperature total maximum daily load development Author: Oregon. Dept. of Environmental Quality Close

• 2. [Image] Heat Flow of Oregon

  	An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. ...
  	Citation × Citation Citation Abstract Copy Title: Heat Flow of Oregon Author: Blackwell, D.D. Year: 1978 An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. The 1:1,000,000 scale heat flow map is contoured at 20 mW/m/sup 2/ (0.5 HFU) intervals. Also presented are maps of heat flow and temperature at a depth of 1 km averaged for 1/sup 0/ x 1/sup 0/ intervals. Histograms and averages of geothermal gradient and heat flow for the State of Oregon and for the various physiographic provinces within Oregon are also included. The unweighted mean flow for Oregon is 81.3 +- 2.7 mW/m/sup 2/ (1.94 +- 0.06 HFU). The average unweighted geothermal gradient is 65.3 +- 2.5/sup 0/C/km. The average heat flow value weighted on the basis of geographic area is 68 +- 5 mW/m/sup 2/ (1.63 +- 0.12 HFU) and the average weighted geothermal gradient is 55.0 +- 5/sup 0/C/km Title: Heat Flow of Oregon Author: Blackwell, D.D. Year: 1978 An extensive new heat flow and geothermal gradient data set for the State of Oregon is presented on a contour map of heat flow at a scale of 1:1,000,000 and is summarized in several figures and tables. The 1:1,000,000 scale heat flow map is contoured at 20 mW/m/sup 2/ (0.5 HFU) intervals. Also presented are maps of heat flow and temperature at a depth of 1 km averaged for 1/sup 0/ x 1/sup 0/ intervals. Histograms and averages of geothermal gradient and heat flow for the State of Oregon and for the various physiographic provinces within Oregon are also included. The unweighted mean flow for Oregon is 81.3 +- 2.7 mW/m/sup 2/ (1.94 +- 0.06 HFU). The average unweighted geothermal gradient is 65.3 +- 2.5/sup 0/C/km. The average heat flow value weighted on the basis of geographic area is 68 +- 5 mW/m/sup 2/ (1.63 +- 0.12 HFU) and the average weighted geothermal gradient is 55.0 +- 5/sup 0/C/km Close

• 3. [Article] Past climate variability in southwestern Oregon and relationships with regional and hemispheric climate

  This dissertation presents the results of three studies that assessed climate variability on short and long timescales in western United States. The growth of carbonate formations in caves (speleothems) ...

  Citation × Citation Citation Abstract Copy Title: Past climate variability in southwestern Oregon and relationships with regional and hemispheric climate Author: Ersek, Vasile This dissertation presents the results of three studies that assessed climate variability on short and long timescales in western United States. The growth of carbonate formations in caves (speleothems) is used to infer the timing and amplitude of past climate variability. We first assess the controls on speleothem growth for the past 380 000 years by combining high-density U-Th dating with a regional climate model and an energy balance model. The majority of speleothem growth occurred overwhelmingly during interglacial periods and glacial periods were characterized by little or no growth. We assess the mechanisms responsible for growth cessation during the peak of the last glaciation (LGM), 21 000 years ago, with a regional climate model and determine that a combination of drier LGM conditions with a change in the seasonal cycle of the surface water balance provides a feedback mechanism that limited recharge to the deeper soil and reduced or eliminated drip water in the cave. The energy balance model supports this mechanism by indicating that cave temperatures did not drop below the freezing point of water at any time during the last glaciation. We then evaluate the climatic significance of stable isotopes of oxygen in rainwater collected in southwestern Oregon in order to accurately interpret the isotopic record of speleothems. We establish that temperature plays an important role in controlling the distribution of oxygen isotopes in rainwater and therefore speleothems in southwestern Oregon can preserve a record of temperature changes through time. Finally, we present a high-resolution paleoclimate record using speleothems from a cave in Oregon that grew during the last 9000 years and during the middle of the last interglaciation. We find the winter temperatures were sensitive to winter solar insolation and varied in a quasi-cyclical pattern on millennial timescales. This pattern was characteristic of both regional and hemispheric variability as indicated by similarities of our record with other regional and hemispheric climate reconstructions. It appears that higher climate variability in the past was associated with warming trends, with the implication that global warming may make the climate more unstable in the future. Climate variability during the last interglacial period was characterized by different scales of millennial and centennial climate variability compared with the Holocene. Title: Past climate variability in southwestern Oregon and relationships with regional and hemispheric climate Author: Ersek, Vasile This dissertation presents the results of three studies that assessed climate variability on short and long timescales in western United States. The growth of carbonate formations in caves (speleothems) is used to infer the timing and amplitude of past climate variability. We first assess the controls on speleothem growth for the past 380 000 years by combining high-density U-Th dating with a regional climate model and an energy balance model. The majority of speleothem growth occurred overwhelmingly during interglacial periods and glacial periods were characterized by little or no growth. We assess the mechanisms responsible for growth cessation during the peak of the last glaciation (LGM), 21 000 years ago, with a regional climate model and determine that a combination of drier LGM conditions with a change in the seasonal cycle of the surface water balance provides a feedback mechanism that limited recharge to the deeper soil and reduced or eliminated drip water in the cave. The energy balance model supports this mechanism by indicating that cave temperatures did not drop below the freezing point of water at any time during the last glaciation. We then evaluate the climatic significance of stable isotopes of oxygen in rainwater collected in southwestern Oregon in order to accurately interpret the isotopic record of speleothems. We establish that temperature plays an important role in controlling the distribution of oxygen isotopes in rainwater and therefore speleothems in southwestern Oregon can preserve a record of temperature changes through time. Finally, we present a high-resolution paleoclimate record using speleothems from a cave in Oregon that grew during the last 9000 years and during the middle of the last interglaciation. We find the winter temperatures were sensitive to winter solar insolation and varied in a quasi-cyclical pattern on millennial timescales. This pattern was characteristic of both regional and hemispheric variability as indicated by similarities of our record with other regional and hemispheric climate reconstructions. It appears that higher climate variability in the past was associated with warming trends, with the implication that global warming may make the climate more unstable in the future. Climate variability during the last interglacial period was characterized by different scales of millennial and centennial climate variability compared with the Holocene. Close

• 4. [Article] Seasonal and across-shelf trends of the phytoplankton community of the Oregon coastal environment

  This project, part of the Northeast Pacific GLOBEC Long Term Observation Project (NEPGLOBEC- LTOP), constitutes the first multi-year study of phytoplankton variability in the Oregon coastal environment. ...

  Citation × Citation Citation Abstract Copy Title: Seasonal and across-shelf trends of the phytoplankton community of the Oregon coastal environment Author: Wheeler, Patricia A., Moses, Woody C. This project, part of the Northeast Pacific GLOBEC Long Term Observation Project (NEPGLOBEC- LTOP), constitutes the first multi-year study of phytoplankton variability in the Oregon coastal environment. The work divides into two studies: analysis of interseasonal change and analysis of detailed changes within the summer upwelling period. In the first study, I found that the majority of variability in phytoplankton biomass in this system is due to changes in the abundance of chain forming diatoms, particularly diatoms of the genera Chaetoceros and Skeletonema. The abundance of nanoflagellates (<10 μm) remains constant across the shelf. They dominate the phytoplankton community in the offshore stations and larger cells, usually diatoms, are added inshore. Cyanobacteria, though numerically abundant, never comprise more than approximately 10% of phytoplankton biomass. Variation within the summer phytoplankton bloom over the shelf was analyzed based on results from the four NEP-GLOBEC-LTOP summer cruises between August 1998 and July 2001. Nutrient concentrations during the summer upwelling blooms show a linear decrease with increasing temperature from 8 to 12° C. Over this range of temperatures, total Chl a and phytoplankton biomass increase, though not significantly, and the % Chl a >10 μm remains high (>50 %). Above 12° C, when inorganic nutrients are depleted or greatly reduced, total Chl a and % Chl a >10 μm decrease. The diatom genera Chaetoceros and Skeletonema are also responsible for the majority of the variability in phytoplankton stock during the summer phytoplankton bloom. Dinoflagellates, although present, are consistently less abundant than diatoms. Title: Seasonal and across-shelf trends of the phytoplankton community of the Oregon coastal environment Author: Wheeler, Patricia A., Moses, Woody C. This project, part of the Northeast Pacific GLOBEC Long Term Observation Project (NEPGLOBEC- LTOP), constitutes the first multi-year study of phytoplankton variability in the Oregon coastal environment. The work divides into two studies: analysis of interseasonal change and analysis of detailed changes within the summer upwelling period. In the first study, I found that the majority of variability in phytoplankton biomass in this system is due to changes in the abundance of chain forming diatoms, particularly diatoms of the genera Chaetoceros and Skeletonema. The abundance of nanoflagellates (<10 μm) remains constant across the shelf. They dominate the phytoplankton community in the offshore stations and larger cells, usually diatoms, are added inshore. Cyanobacteria, though numerically abundant, never comprise more than approximately 10% of phytoplankton biomass. Variation within the summer phytoplankton bloom over the shelf was analyzed based on results from the four NEP-GLOBEC-LTOP summer cruises between August 1998 and July 2001. Nutrient concentrations during the summer upwelling blooms show a linear decrease with increasing temperature from 8 to 12° C. Over this range of temperatures, total Chl a and phytoplankton biomass increase, though not significantly, and the % Chl a >10 μm remains high (>50 %). Above 12° C, when inorganic nutrients are depleted or greatly reduced, total Chl a and % Chl a >10 μm decrease. The diatom genera Chaetoceros and Skeletonema are also responsible for the majority of the variability in phytoplankton stock during the summer phytoplankton bloom. Dinoflagellates, although present, are consistently less abundant than diatoms. Close

• 5. [Article] Analysis of habitat features and abundance of young-of-the-year fishes off of the central Oregon coast

  This project is part of ongoing research, which has been extended to include temporal variation. Dr. Lorenzo Ciannelli has also been brought onto this project as of Fall 2015.

  Citation × Citation Citation Abstract Copy Title: Analysis of habitat features and abundance of young-of-the-year fishes off of the central Oregon coast Author: Brodeur, Richard, Yergey, Matthew, Wakefield, W. Waldo, Haven, Katlyn This project is part of ongoing research, which has been extended to include temporal variation. Dr. Lorenzo Ciannelli has also been brought onto this project as of Fall 2015. Title: Analysis of habitat features and abundance of young-of-the-year fishes off of the central Oregon coast Author: Brodeur, Richard, Yergey, Matthew, Wakefield, W. Waldo, Haven, Katlyn This project is part of ongoing research, which has been extended to include temporal variation. Dr. Lorenzo Ciannelli has also been brought onto this project as of Fall 2015. Close

• 6. [Article] Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades

  This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches ...

  Citation × Citation Citation Abstract Copy Title: Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades Author: Ratcliff, Christopher J. This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches of the McKenzie River watershed of the Oregon Cascade Mountains. We tested the use of Δ¹³C values from latewood, corroborated by tree-ring width chronologies as precipitation proxies to develop correlations between moisture stress and climate variables. Tree species at each site included Douglas-fir and mountain hemlock. Interpolated meteorological and snowpack data included snow water equivalent (SWE), precipitation, atmospheric temperature, vapor pressure deficit (VPD), relative humidity (RH), and a metric estimating growing season length. Significant correlations between latewood Δ¹³C and winter SWE at each site indicated the importance of winter snowpack to our selected tree species (r = 0.35, r = 0.43). Late summer precipitation and relative humidity (RH) were also significantly correlated with Δ¹³C (r = 0.49, r = 0.46; r = 0.43, r = 0.44). High correlations at both sites reinforced that late summer VPD was the primary driver of Δ¹³C (r = - 0.67, r = -0.61), which is often associated with moisture stress. This was further supported by correlations between air temperature and Δ¹³C (r = -0.46, r = -0.47), which drives much of the variation in VPD. Growing season length also showed significance in mountain hemlocks at the site with longer average snowpack (r = -0.22, r = -0.44). Moisture supplied by spring snow melt is a seasonably limited resource, nonetheless both sites clearly showed that snowpack acts as a valuable moisture subsidy to coniferous mountain forests in the Oregon Cascades. This study acts as a useful case study for future investigations into the relationship between snowpack and forest health in the Pacific North West. Title: Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades Author: Ratcliff, Christopher J. This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches of the McKenzie River watershed of the Oregon Cascade Mountains. We tested the use of Δ¹³C values from latewood, corroborated by tree-ring width chronologies as precipitation proxies to develop correlations between moisture stress and climate variables. Tree species at each site included Douglas-fir and mountain hemlock. Interpolated meteorological and snowpack data included snow water equivalent (SWE), precipitation, atmospheric temperature, vapor pressure deficit (VPD), relative humidity (RH), and a metric estimating growing season length. Significant correlations between latewood Δ¹³C and winter SWE at each site indicated the importance of winter snowpack to our selected tree species (r = 0.35, r = 0.43). Late summer precipitation and relative humidity (RH) were also significantly correlated with Δ¹³C (r = 0.49, r = 0.46; r = 0.43, r = 0.44). High correlations at both sites reinforced that late summer VPD was the primary driver of Δ¹³C (r = - 0.67, r = -0.61), which is often associated with moisture stress. This was further supported by correlations between air temperature and Δ¹³C (r = -0.46, r = -0.47), which drives much of the variation in VPD. Growing season length also showed significance in mountain hemlocks at the site with longer average snowpack (r = -0.22, r = -0.44). Moisture supplied by spring snow melt is a seasonably limited resource, nonetheless both sites clearly showed that snowpack acts as a valuable moisture subsidy to coniferous mountain forests in the Oregon Cascades. This study acts as a useful case study for future investigations into the relationship between snowpack and forest health in the Pacific North West. Close

• 7. [Article] Specific consensus statement on the likely impacts of climate change on the Pacific Northwest

  The signatories of this statement seek to describe the state of scientific knowledge regarding likely impacts of climate change to the Pacific Northwest region. The intent is to assist Governor Kulongoski’s ...

  Citation × Citation Citation Abstract Copy Title: Specific consensus statement on the likely impacts of climate change on the Pacific Northwest The signatories of this statement seek to describe the state of scientific knowledge regarding likely impacts of climate change to the Pacific Northwest region. The intent is to assist Governor Kulongoski’s Advisory Group on Global Warming in its task of developing a greenhouse gas emission reduction strategy for Oregon. The signatories agree that climate change is underway and that it is having global effects as well as impacts in the Pacific Northwest region. Title: Specific consensus statement on the likely impacts of climate change on the Pacific Northwest The signatories of this statement seek to describe the state of scientific knowledge regarding likely impacts of climate change to the Pacific Northwest region. The intent is to assist Governor Kulongoski’s Advisory Group on Global Warming in its task of developing a greenhouse gas emission reduction strategy for Oregon. The signatories agree that climate change is underway and that it is having global effects as well as impacts in the Pacific Northwest region. Close

• 8. [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

• 9. [Article] Factors influencing nest success of greater sandhill cranes at Malheur National Wildlife Refuge, Oregon

  I developed a priori hypotheses and used logistic regression to model Greater Sandhill Crane (Grus canadensis tabida) nest success in relation to weather, habitat and management variables for cranes breeding ...

  Citation × Citation Citation Abstract Copy Title: Factors influencing nest success of greater sandhill cranes at Malheur National Wildlife Refuge, Oregon Author: Ivey, Gary L. I developed a priori hypotheses and used logistic regression to model Greater Sandhill Crane (Grus canadensis tabida) nest success in relation to weather, habitat and management variables for cranes breeding at Malheur National Wildlife Refuge (MNWR) in southeast Oregon. My primary interest was to investigate the effects of habitat conditions and management practices on nest success as these factors can be influenced by managers. However, I also included variables for weather, water supply, and nest initiation date to provide a context for understanding the relative importance of management actions and habitat conditions. I monitored 506 nests over 9 breeding seasons; mean apparent nest success was 72% ± 4% and varied from 51 to 87%. Nest success varied by habitat management within a field, nest-season temperatures, and water at the nest site. A second analysis which included a subset of nests with nest initiation data revealed that nest success declined with initiation and was higher during years of moderate recipitation. Variable importance analysis indicated initiation date had a greater influence on nest success (0.99) than land use (0.74), water depth (0.50), water supply (0.42), or temperature (0.30). Grazing, haying and predator control had no effect on nest success, while burning had a negative effect, but only during the nesting season following the burn. The lack of a predator control effect may have been due to elimination of individual problem animals before the study commenced, and a protracted effect of the control program. It may also be due to the relatively smaller importance of predator control at higher nest success rates. Nest success at MNWR was higher during my study than in most studies and the low proportion of failed nests may have reduced my ability to detect influences of some variables such as land use practices and predator control. My study is the first to quantify the effect of temperature and moisture conditions on nest success and the results suggest adequate water availability is important for nesting cranes. It affirms the importance of water depth, but not concealment, indicating that the height of cover surrounding a nest is not very important. During the 8-year coyote (Canis latrans) and Common Raven (Corvus corax) control program at MNWR non-target predator populations increased. Such control programs can have unforeseen consequences, such as release of mesopredator populations which can cause additional crane productivity problems. Nest success was relatively high during my study yet productivity was very low, averaging around 3.3 young per 100 pairs from 1995-1998 (GLI, unpublished data). Efforts to further increase nest success at MNWR using predator control are not warranted. The effect of predators on chick survival is likely of more importance and should be quantified to aid in the interpretation of predator control as a management tool. Managers should focus on providing early water to crane territories to facilitate earlier nesting and water levels should be maintained through the nesting season to limit abandonment. Haying and grazing of meadows will likely encourage cranes to nest in deeper water marsh sites. Although burning showed negative effects on nest success during the first season following burns, I advocate continued, but careful use of this important habitat management tool. Lastly, in addition to management to improve nest success, managers should consider efforts to enhance chick and adult survival, as these factors are likely more important than nest success in maintaining populations. Title: Factors influencing nest success of greater sandhill cranes at Malheur National Wildlife Refuge, Oregon Author: Ivey, Gary L. I developed a priori hypotheses and used logistic regression to model Greater Sandhill Crane (Grus canadensis tabida) nest success in relation to weather, habitat and management variables for cranes breeding at Malheur National Wildlife Refuge (MNWR) in southeast Oregon. My primary interest was to investigate the effects of habitat conditions and management practices on nest success as these factors can be influenced by managers. However, I also included variables for weather, water supply, and nest initiation date to provide a context for understanding the relative importance of management actions and habitat conditions. I monitored 506 nests over 9 breeding seasons; mean apparent nest success was 72% ± 4% and varied from 51 to 87%. Nest success varied by habitat management within a field, nest-season temperatures, and water at the nest site. A second analysis which included a subset of nests with nest initiation data revealed that nest success declined with initiation and was higher during years of moderate recipitation. Variable importance analysis indicated initiation date had a greater influence on nest success (0.99) than land use (0.74), water depth (0.50), water supply (0.42), or temperature (0.30). Grazing, haying and predator control had no effect on nest success, while burning had a negative effect, but only during the nesting season following the burn. The lack of a predator control effect may have been due to elimination of individual problem animals before the study commenced, and a protracted effect of the control program. It may also be due to the relatively smaller importance of predator control at higher nest success rates. Nest success at MNWR was higher during my study than in most studies and the low proportion of failed nests may have reduced my ability to detect influences of some variables such as land use practices and predator control. My study is the first to quantify the effect of temperature and moisture conditions on nest success and the results suggest adequate water availability is important for nesting cranes. It affirms the importance of water depth, but not concealment, indicating that the height of cover surrounding a nest is not very important. During the 8-year coyote (Canis latrans) and Common Raven (Corvus corax) control program at MNWR non-target predator populations increased. Such control programs can have unforeseen consequences, such as release of mesopredator populations which can cause additional crane productivity problems. Nest success was relatively high during my study yet productivity was very low, averaging around 3.3 young per 100 pairs from 1995-1998 (GLI, unpublished data). Efforts to further increase nest success at MNWR using predator control are not warranted. The effect of predators on chick survival is likely of more importance and should be quantified to aid in the interpretation of predator control as a management tool. Managers should focus on providing early water to crane territories to facilitate earlier nesting and water levels should be maintained through the nesting season to limit abandonment. Haying and grazing of meadows will likely encourage cranes to nest in deeper water marsh sites. Although burning showed negative effects on nest success during the first season following burns, I advocate continued, but careful use of this important habitat management tool. Lastly, in addition to management to improve nest success, managers should consider efforts to enhance chick and adult survival, as these factors are likely more important than nest success in maintaining populations. Close

• 10. [Article] Spatiotemporal Drivers of Seabird Distribution at the Pacific Marine Energy Center off Newport, Oregon

  The central Oregon coast was selected as an ideal site for wave energy development and establishment of the Pacific Marine Energy Center (PMEC). PMEC will consist of two nearshore sites, one north (NETS) ...

  Citation × Citation Citation Abstract Copy Title: Spatiotemporal Drivers of Seabird Distribution at the Pacific Marine Energy Center off Newport, Oregon Author: Porquez, Jessica M. The central Oregon coast was selected as an ideal site for wave energy development and establishment of the Pacific Marine Energy Center (PMEC). PMEC will consist of two nearshore sites, one north (NETS) and one south (SETS) of the Yaquina River, Oregon. Our study aims to assess how the development of wave energy sites might impact marine birds. We used vessel-based strip transect surveys to detect spatial and temporal patterns of seabirds during 28 surveys of NETS and SETS from 2013-2015. We also conducted 29 surveys along the Newport Hydrographic Line (NHL) (2006-2009, 2013-2015), a cross-shelf oceanographic sampling line that extends 40 km west of NETS. We collected in situ measurements of surface conductivity, temperature and fluorescence to test correlations between spatial variables and seabird abundance. Common murres (Uria aalge) were the most abundant resident species (70%) while sooty shearwaters (Puffinus griseus) were the most abundant migratory species (78%). We identified 7 focal species (common murres, sooty shearwaters, Brandt's and pelagic cormorants (Phalacrocorax penicillatus and pelagicus), western gull (Larus occidentalis), Cassin's auklet (Ptychoramphus aleuticus), and red-necked phalaropes (Phalaropus lobatus), 5 foraging niches and 3 species of interest for analysis. We used non-metric multidimensional scaling ordinations to assess seasonal shifts in the seabird community at a focal species and foraging group level. Both ordinations depicted strong seasonal gradients with distinct seasonal communities. Focal species were also driven by a distance to shore gradient, while foraging niches were more influenced by foraging type (diving versus surface feeding). The shoreward shift or outward dispersal of species appears driven by a combination of factors, including the diffusion of nearshore concentration of murres and cormorants on Yaquina Head post chick fledging, and the inshore movement of migratory species with the onset of upwelling and greater prey abundance. We employed generalized additive mixed models for the focal species, and tested for correlations with in situ data (salinity, temperature and fluorescence), depth, substrate, season, and a random 'site' effect. We identified correlations between several species and measured oceanographic variables, which indicated species' selection of specific water masses. With Inverse Distance Weighted maps we detected high use zones by sooty shearwaters and common murres outside of both site boundaries, except during the spring and summer, when murres occur densely within the NETS. None of our observed species of concern (brown pelicans (Pelicanus occidentalis), black footed albatrosses (Phoebastria nigiripes) and marbled murrelets, (Brachyramphus marmoratus)) were detected within either site boundary. Rather, pelicans and murrelets were observed inshore of the SETS and south of the NETS, and albatrosses were all detected west of the sites. We observed overall low abundance of focal species within the sites, relative to adjacent areas, although the whole study area appears to be productive foraging habitat used by many species. As a baseline characterization of the seabird community off Newport, this work can help inform citing and permitting processes of similar wave energy test facilities and provide a platform for continued monitoring of seabirds in the area. Title: Spatiotemporal Drivers of Seabird Distribution at the Pacific Marine Energy Center off Newport, Oregon Author: Porquez, Jessica M. The central Oregon coast was selected as an ideal site for wave energy development and establishment of the Pacific Marine Energy Center (PMEC). PMEC will consist of two nearshore sites, one north (NETS) and one south (SETS) of the Yaquina River, Oregon. Our study aims to assess how the development of wave energy sites might impact marine birds. We used vessel-based strip transect surveys to detect spatial and temporal patterns of seabirds during 28 surveys of NETS and SETS from 2013-2015. We also conducted 29 surveys along the Newport Hydrographic Line (NHL) (2006-2009, 2013-2015), a cross-shelf oceanographic sampling line that extends 40 km west of NETS. We collected in situ measurements of surface conductivity, temperature and fluorescence to test correlations between spatial variables and seabird abundance. Common murres (Uria aalge) were the most abundant resident species (70%) while sooty shearwaters (Puffinus griseus) were the most abundant migratory species (78%). We identified 7 focal species (common murres, sooty shearwaters, Brandt's and pelagic cormorants (Phalacrocorax penicillatus and pelagicus), western gull (Larus occidentalis), Cassin's auklet (Ptychoramphus aleuticus), and red-necked phalaropes (Phalaropus lobatus), 5 foraging niches and 3 species of interest for analysis. We used non-metric multidimensional scaling ordinations to assess seasonal shifts in the seabird community at a focal species and foraging group level. Both ordinations depicted strong seasonal gradients with distinct seasonal communities. Focal species were also driven by a distance to shore gradient, while foraging niches were more influenced by foraging type (diving versus surface feeding). The shoreward shift or outward dispersal of species appears driven by a combination of factors, including the diffusion of nearshore concentration of murres and cormorants on Yaquina Head post chick fledging, and the inshore movement of migratory species with the onset of upwelling and greater prey abundance. We employed generalized additive mixed models for the focal species, and tested for correlations with in situ data (salinity, temperature and fluorescence), depth, substrate, season, and a random 'site' effect. We identified correlations between several species and measured oceanographic variables, which indicated species' selection of specific water masses. With Inverse Distance Weighted maps we detected high use zones by sooty shearwaters and common murres outside of both site boundaries, except during the spring and summer, when murres occur densely within the NETS. None of our observed species of concern (brown pelicans (Pelicanus occidentalis), black footed albatrosses (Phoebastria nigiripes) and marbled murrelets, (Brachyramphus marmoratus)) were detected within either site boundary. Rather, pelicans and murrelets were observed inshore of the SETS and south of the NETS, and albatrosses were all detected west of the sites. We observed overall low abundance of focal species within the sites, relative to adjacent areas, although the whole study area appears to be productive foraging habitat used by many species. As a baseline characterization of the seabird community off Newport, this work can help inform citing and permitting processes of similar wave energy test facilities and provide a platform for continued monitoring of seabirds in the area. Close