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• 1. [Article] Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters

  Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. ...

  Citation × Citation Citation Abstract Copy Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Close

• 2. [Article] Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives

  Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in ...

  Citation × Citation Citation Abstract Copy Title: Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives Author: Strecker, Angela L., Brittain, Jeffrey Thomas Year: 2017 Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in the largest water development project in the US history, the Columbia Basin Project (CBP; eastern Washington, USA), which also altered environmental conditions; however, the ecological consequences are largely unknown. Using a historical dataset, we examined long-term patterns in zooplankton communities, water chemistry and clarity, testing the hypothesis that increased connectivity will result in taxonomic homogenization. Further, we tested contemporary drivers of communities using a comprehensive set of environmental and landscape variables. Waterbodies were sampled for zooplankton community composition as well as physical and chemical variables inside and outside the CBP using methods consistent with historical studies. We found significant declines in salinity inside the CBP, whereas changes in water clarity were prevalent across all waterbodies. Increased connectivity via canals homogenized zooplankton communities over time, as well as increasing regional richness. Other long-term changes in zooplankton communities may be related to climate change, invasive species, and land-use changes. Synthesis and applications. Though canals may offer species spatial refugia, homogenization may decrease resilience to environmental stressors. These new hybrid aquatic landscapes, or hydroscapes, should be considered carefully in future water development, including specific plans for monitoring of species and environmental conditions, as well as mitigation of undesirable conditions and/or non-native species. Title: Increased Habitat Connectivity Homogenizes Freshwater Communities: Historical and Landscape Perspectives Author: Strecker, Angela L., Brittain, Jeffrey Thomas Year: 2017 Increases in habitat connectivity can have consequences for taxonomic, functional, and genetic diversity of communities. Previously isolated aquatic habitats were connected with canals and pipelines in the largest water development project in the US history, the Columbia Basin Project (CBP; eastern Washington, USA), which also altered environmental conditions; however, the ecological consequences are largely unknown. Using a historical dataset, we examined long-term patterns in zooplankton communities, water chemistry and clarity, testing the hypothesis that increased connectivity will result in taxonomic homogenization. Further, we tested contemporary drivers of communities using a comprehensive set of environmental and landscape variables. Waterbodies were sampled for zooplankton community composition as well as physical and chemical variables inside and outside the CBP using methods consistent with historical studies. We found significant declines in salinity inside the CBP, whereas changes in water clarity were prevalent across all waterbodies. Increased connectivity via canals homogenized zooplankton communities over time, as well as increasing regional richness. Other long-term changes in zooplankton communities may be related to climate change, invasive species, and land-use changes. Synthesis and applications. Though canals may offer species spatial refugia, homogenization may decrease resilience to environmental stressors. These new hybrid aquatic landscapes, or hydroscapes, should be considered carefully in future water development, including specific plans for monitoring of species and environmental conditions, as well as mitigation of undesirable conditions and/or non-native species. Close

• 3. [Article] The effect of human activity on the middle course of the Tualatin River, Oregon

  A diurnal study of biological, chemical, and physical parameters was made on the middle course of the, Tualatin River, which drains a 1840 km2 (711 mi2) basin adjacent to metropolitan Portland, Oregon. ...

  Citation × Citation Citation Abstract Copy Title: The effect of human activity on the middle course of the Tualatin River, Oregon Author: Carter, Lolita M. Year: 1975 A diurnal study of biological, chemical, and physical parameters was made on the middle course of the, Tualatin River, which drains a 1840 km2 (711 mi2) basin adjacent to metropolitan Portland, Oregon. This portion of the river lies along land in transition of use from rural agriculture to highly urbanized development. There is no nutrient loading of the river from farming practices because there was no return of water from summer, sprinkler irrigation of commercial crops. However, irrigation significantly reduces the volume of water in the river in the summers. Effluents from sewage treatment plants flowing into the tributaries that drain the highly urbanized eastern areas of the river basin are the main cause of degraded water quality and algal biomass in the lower reaches of the river. The Tualatin River above the mouth of Rock Creek is relatively unpolluted, but downstream from Rock Creek the river is highly eutrophic and during the periods of low flow in the summer serves as a sewage oxidation channel. In this same portion of the river there is also evidence that nitrification occurs. Winter floods leach nitrate-nitrogen from the basin, but in the summer the possibility exists. that nitrate-nitrogen may be a limiting nutrient for algal productivity in the river above Hillsboro. The principal source of poly-phosphates is from sewage treatment plant effluents, but concentrations of poly-phosphates in the middle reaches of the river indicate that there is a natural source of poly- and/or ortho-phosphates in the watershed. Removal of phosphorous compounds from the effluents probably would not affect the large algal blooms occurring in the river below Hillsboro. Trace metal analyses indicated that iron, potassium, nickel, zinc, lead, copper, cobalt, and chromium concentrations were higher during flooding. Turbidity readings suggest that these trace elements are deposited on the floodplain. Melted snow water, which caused one of the winter floods, contained concentrations of zinc, ·copper, and lead greater than those found in the river during the flood. Greater concentrations of arsenic and zinc came from farmland than from urban areas. Diversities of the net plankton as measured by the Shannon-Weaver Index did not change from season to season, nor with downstream flow. Species in the net plankton were benthic forms at the upper stations and planktonic forms downstream from Hillsboro, especially in the summer when the reduced flow caused the river to pond. The enriched effluents from Rock Creek did not affect the diversity of the organisms downstream, but supported a larger biomass. By rating the diversities with other studies it was found that the middle course of the Tualatin River is eutrophic but not heavily polluted. A diurnal study was especially valuable from April to September, inclusive, when insolation and temperatures favored biological activities such as photosynthesis and decomposition. From November to January little diurnal change in the water quality was found. Farming had its greatest impact in the quantity of water and municipalities had a more serious impact on the water quality in the middle course of the Tualatin River. Even with the reduced flow from agricultural irrigation, the river can maintain relatively good water quality, except when effluents from sewage plants caused highly eutrophic conditions. Title: The effect of human activity on the middle course of the Tualatin River, Oregon Author: Carter, Lolita M. Year: 1975 A diurnal study of biological, chemical, and physical parameters was made on the middle course of the, Tualatin River, which drains a 1840 km2 (711 mi2) basin adjacent to metropolitan Portland, Oregon. This portion of the river lies along land in transition of use from rural agriculture to highly urbanized development. There is no nutrient loading of the river from farming practices because there was no return of water from summer, sprinkler irrigation of commercial crops. However, irrigation significantly reduces the volume of water in the river in the summers. Effluents from sewage treatment plants flowing into the tributaries that drain the highly urbanized eastern areas of the river basin are the main cause of degraded water quality and algal biomass in the lower reaches of the river. The Tualatin River above the mouth of Rock Creek is relatively unpolluted, but downstream from Rock Creek the river is highly eutrophic and during the periods of low flow in the summer serves as a sewage oxidation channel. In this same portion of the river there is also evidence that nitrification occurs. Winter floods leach nitrate-nitrogen from the basin, but in the summer the possibility exists. that nitrate-nitrogen may be a limiting nutrient for algal productivity in the river above Hillsboro. The principal source of poly-phosphates is from sewage treatment plant effluents, but concentrations of poly-phosphates in the middle reaches of the river indicate that there is a natural source of poly- and/or ortho-phosphates in the watershed. Removal of phosphorous compounds from the effluents probably would not affect the large algal blooms occurring in the river below Hillsboro. Trace metal analyses indicated that iron, potassium, nickel, zinc, lead, copper, cobalt, and chromium concentrations were higher during flooding. Turbidity readings suggest that these trace elements are deposited on the floodplain. Melted snow water, which caused one of the winter floods, contained concentrations of zinc, ·copper, and lead greater than those found in the river during the flood. Greater concentrations of arsenic and zinc came from farmland than from urban areas. Diversities of the net plankton as measured by the Shannon-Weaver Index did not change from season to season, nor with downstream flow. Species in the net plankton were benthic forms at the upper stations and planktonic forms downstream from Hillsboro, especially in the summer when the reduced flow caused the river to pond. The enriched effluents from Rock Creek did not affect the diversity of the organisms downstream, but supported a larger biomass. By rating the diversities with other studies it was found that the middle course of the Tualatin River is eutrophic but not heavily polluted. A diurnal study was especially valuable from April to September, inclusive, when insolation and temperatures favored biological activities such as photosynthesis and decomposition. From November to January little diurnal change in the water quality was found. Farming had its greatest impact in the quantity of water and municipalities had a more serious impact on the water quality in the middle course of the Tualatin River. Even with the reduced flow from agricultural irrigation, the river can maintain relatively good water quality, except when effluents from sewage plants caused highly eutrophic conditions. Close

• 4. [Article] Physiological ecology and structure of benthic communities in a woodland stream

  This thesis reports a portion of a general ecological study of a stream under conditions of controlled flow and low levels of organic enrichment. It is concerned with the effects of experimental variations of ...

  Citation × Citation Citation Abstract Copy Title: Physiological ecology and structure of benthic communities in a woodland stream Author: Reese, Weldon Harold This thesis reports a portion of a general ecological study of a stream under conditions of controlled flow and low levels of organic enrichment. It is concerned with the effects of experimental variations of light intensity and concentration of soluble organic enrichment imposed on seasonal variations of temperature and total light energy received upon the periphyton and benthic plants. Suitable enrichment was predicated on establishment and maintenance of an abundant growth of Sphaerotilus and involved the isolation and study of this organism in pure cultures, in laboratory streams as well as in the experimental stream. Abundant growth of Sphaerotilus was obtained in cultures at temperatures of 5, 10, 15, 20, 25, and 30°C while in the laboratory streams and the experimental stream, the organism produced abundant growths at a range of temperatures from 2 to 12°C. A variety of carbon and nitrogen sources was investigated for maintenance of growth of Sphaerotilus. Abundant growth was produced when the enrichment included a specific nitrogen source combined with a specific carbon source. A carbon-nitrogen ratio of 8 to 1 proved satisfactory for maintaining Sphaerotilus in the stream. An investigation of the cropping effect of stream snails indicated that the presence of large numbers of snails decreased the standing crop of Sphaerotilus both in the laboratory streams and the experimental stream. A method was devised for determining the daily mean percentages of full sunlight reaching the four experimental sections of Berry Creek. Approximately 4 percent reached the shaded sections and 50 percent reached the light sections during the summer months. The range of mean saturating light intensities on the four experimental sections was from 250 to 950 footcandles. Methods designed to sample the plant communities in the experimental sections of the stream included: artificial substrates (microscope slides) used to observe the density and diversity of micro-algae; a system of grids used to record distribution of the plant biomass; and the removal of a portion of the stream substrate for the detailed examination of the benthic community. Both microscopic and macroscopic observations indicated that twice as many species and greater numbers of autotrophic organisms were present in the unenriched than in the enriched sections. Sub-samples of the harvested and homogenized materials scoured from the stream substrate, were used to determine biomass, organic matter, caloric content and pigment content. The biomasses from the enriched sections were greater than those from the unenriched sections, but contained large amounts of silt and were lower in organic matter and caloric content. The mean percentages of organic matter for the sections were: shaded, unenriched-33; light, unenriched-42; shaded, enriched-19 and light, enriched-19. The range of chlorophyll a from the four experimental sections was 0.03 to 0.28 g/m². The concentration of chlorophyll, when representing spatial and seasonal variations, is an acceptable measure of the productive ability of communities in shallow, rapidly flowing streams. A photosynthesis-respiration chamber was used to determine primary production and community respiration for each of the experimental sections. The range of rates of gross primary production expressed as mean O₂,g /m²/day for the unenriched sections was 0.62-2.47 and 0.53-0.59 for the enriched sections. Annual rates of gross primary production in glucose equivalents ranged from 0.07 kg/m² for the enriched sections to 0.30 for the unenriched. The stream communities were characterized as heterotrophic communities with production-respiration ratios ranging from 0.47-0.65 for the unenriched and 0.16-0.20 for the enriched sections. The efficiency of the fixation of light energy as organic matter was 1.90-2.23 for the unenriched and 0.37-2.70 for the enriched sections. The photosynthetic efficiencies of the communities on the experimental sections of Berry Creek were much lower than those reported for most laboratory communities, but were comparable to other natural aquatic communities. Title: Physiological ecology and structure of benthic communities in a woodland stream Author: Reese, Weldon Harold This thesis reports a portion of a general ecological study of a stream under conditions of controlled flow and low levels of organic enrichment. It is concerned with the effects of experimental variations of light intensity and concentration of soluble organic enrichment imposed on seasonal variations of temperature and total light energy received upon the periphyton and benthic plants. Suitable enrichment was predicated on establishment and maintenance of an abundant growth of Sphaerotilus and involved the isolation and study of this organism in pure cultures, in laboratory streams as well as in the experimental stream. Abundant growth of Sphaerotilus was obtained in cultures at temperatures of 5, 10, 15, 20, 25, and 30°C while in the laboratory streams and the experimental stream, the organism produced abundant growths at a range of temperatures from 2 to 12°C. A variety of carbon and nitrogen sources was investigated for maintenance of growth of Sphaerotilus. Abundant growth was produced when the enrichment included a specific nitrogen source combined with a specific carbon source. A carbon-nitrogen ratio of 8 to 1 proved satisfactory for maintaining Sphaerotilus in the stream. An investigation of the cropping effect of stream snails indicated that the presence of large numbers of snails decreased the standing crop of Sphaerotilus both in the laboratory streams and the experimental stream. A method was devised for determining the daily mean percentages of full sunlight reaching the four experimental sections of Berry Creek. Approximately 4 percent reached the shaded sections and 50 percent reached the light sections during the summer months. The range of mean saturating light intensities on the four experimental sections was from 250 to 950 footcandles. Methods designed to sample the plant communities in the experimental sections of the stream included: artificial substrates (microscope slides) used to observe the density and diversity of micro-algae; a system of grids used to record distribution of the plant biomass; and the removal of a portion of the stream substrate for the detailed examination of the benthic community. Both microscopic and macroscopic observations indicated that twice as many species and greater numbers of autotrophic organisms were present in the unenriched than in the enriched sections. Sub-samples of the harvested and homogenized materials scoured from the stream substrate, were used to determine biomass, organic matter, caloric content and pigment content. The biomasses from the enriched sections were greater than those from the unenriched sections, but contained large amounts of silt and were lower in organic matter and caloric content. The mean percentages of organic matter for the sections were: shaded, unenriched-33; light, unenriched-42; shaded, enriched-19 and light, enriched-19. The range of chlorophyll a from the four experimental sections was 0.03 to 0.28 g/m². The concentration of chlorophyll, when representing spatial and seasonal variations, is an acceptable measure of the productive ability of communities in shallow, rapidly flowing streams. A photosynthesis-respiration chamber was used to determine primary production and community respiration for each of the experimental sections. The range of rates of gross primary production expressed as mean O₂,g /m²/day for the unenriched sections was 0.62-2.47 and 0.53-0.59 for the enriched sections. Annual rates of gross primary production in glucose equivalents ranged from 0.07 kg/m² for the enriched sections to 0.30 for the unenriched. The stream communities were characterized as heterotrophic communities with production-respiration ratios ranging from 0.47-0.65 for the unenriched and 0.16-0.20 for the enriched sections. The efficiency of the fixation of light energy as organic matter was 1.90-2.23 for the unenriched and 0.37-2.70 for the enriched sections. The photosynthetic efficiencies of the communities on the experimental sections of Berry Creek were much lower than those reported for most laboratory communities, but were comparable to other natural aquatic communities. Close