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• 2231. [Article] Mercury distribution in sediments and uptake into an aquatic food web at Cottage Grove Reservoir, Oregon

  The Cottage Grove Reservoir has been impacted by a point source (Black Butte Mine), where mercury mining and processing has occurred within its watershed from the 1890's to the late 1960's. Total mercury ...

  Citation × Citation Citation Abstract Copy Title: Mercury distribution in sediments and uptake into an aquatic food web at Cottage Grove Reservoir, Oregon Author: Morgans, Donna L. The Cottage Grove Reservoir has been impacted by a point source (Black Butte Mine), where mercury mining and processing has occurred within its watershed from the 1890's to the late 1960's. Total mercury concentrations in surface sediments transect samples, core samples, tributary samples, and representative food web species were measured in 2002. Mercury stratigraphy in reservoir sediment cores and tributary surficial sediments from 2002 and 1995 (unpublished data) were compared and contrasted, core dating was performed to estimate sediment deposition rates and long-term trends for mercury accumulation, and mercury contamination in low trophic levels was assessed. Mercury concentrations in tributary stream sediments strongly correlate with its upstream or downstream proximity to the mine. Current results strongly suggest that the mine area is a continuing source of mercury to downstream tributaries with a strong concentration gradient from the area of the mine to the headwaters of the Coast Fork of the Willamette River. Mercury concentrations in surface sediment transects gradually increase from locations near the inlet to the dam, suggesting an increased mercury deposition rate as suspended solids approach the dam. Sediment cores from both time periods were collected from the deepest most stable region of the reservoir which is likely to have the highest sediment accumulation rates. Mercury concentrations from both cores increase from the surface to the bottom of the core. Core dating results indicate that approximately 40 years lapsed before mercury input to the reservoir stabilized and mercury input has remained relatively stable over the last 20 years. In an aquatic foodweb, methylmercury is the most important form of mercury because it is highly bioavailable for uptake into aquatic organisms. Bioaccumulation of mercury into aquatic organisms can occur through multiple pathways including uptake from sediment arid water, through the skin or cuticle, ventilation of gills, or consumption of contaminated sediment or prey. Biomagnification of methylmercury occurs at successively higher trophic levels of a foodweb. Total mercury concentrations were measured in organisms representative three trophic levels including benthic invertebrates, omnivorous/herbivorous amphibians and fish, and piscivorous fish. Mercury concentrations measured in benthic invertebrates (concentrations ranged from 0.035 mg/kg to 0.075 mg/kg wet-weight) and omnivorous/herbivorous amphibians and fish (concentrations ranged from less than 0.02 mg/kg to 0.043 mg/kg wet-weight) suggest little biomagnification has occurred at these trophic levels. Mercury concentrations in epaxial muscle of largemouth bass (concentrations ranged from 0.86 mg/kg to 1.6 mg/kg wet-weight) are at levels of concern for human health, and fish consumption advisories are posted at the Reservoir. Food web results indicate that significant biomagnification is occurring at higher trophic levels within the foodweb. Current studies suggest that elevated mercury concentrations in largemouth bass are strongly linked to the life history characteristics of the fish. Title: Mercury distribution in sediments and uptake into an aquatic food web at Cottage Grove Reservoir, Oregon Author: Morgans, Donna L. The Cottage Grove Reservoir has been impacted by a point source (Black Butte Mine), where mercury mining and processing has occurred within its watershed from the 1890's to the late 1960's. Total mercury concentrations in surface sediments transect samples, core samples, tributary samples, and representative food web species were measured in 2002. Mercury stratigraphy in reservoir sediment cores and tributary surficial sediments from 2002 and 1995 (unpublished data) were compared and contrasted, core dating was performed to estimate sediment deposition rates and long-term trends for mercury accumulation, and mercury contamination in low trophic levels was assessed. Mercury concentrations in tributary stream sediments strongly correlate with its upstream or downstream proximity to the mine. Current results strongly suggest that the mine area is a continuing source of mercury to downstream tributaries with a strong concentration gradient from the area of the mine to the headwaters of the Coast Fork of the Willamette River. Mercury concentrations in surface sediment transects gradually increase from locations near the inlet to the dam, suggesting an increased mercury deposition rate as suspended solids approach the dam. Sediment cores from both time periods were collected from the deepest most stable region of the reservoir which is likely to have the highest sediment accumulation rates. Mercury concentrations from both cores increase from the surface to the bottom of the core. Core dating results indicate that approximately 40 years lapsed before mercury input to the reservoir stabilized and mercury input has remained relatively stable over the last 20 years. In an aquatic foodweb, methylmercury is the most important form of mercury because it is highly bioavailable for uptake into aquatic organisms. Bioaccumulation of mercury into aquatic organisms can occur through multiple pathways including uptake from sediment arid water, through the skin or cuticle, ventilation of gills, or consumption of contaminated sediment or prey. Biomagnification of methylmercury occurs at successively higher trophic levels of a foodweb. Total mercury concentrations were measured in organisms representative three trophic levels including benthic invertebrates, omnivorous/herbivorous amphibians and fish, and piscivorous fish. Mercury concentrations measured in benthic invertebrates (concentrations ranged from 0.035 mg/kg to 0.075 mg/kg wet-weight) and omnivorous/herbivorous amphibians and fish (concentrations ranged from less than 0.02 mg/kg to 0.043 mg/kg wet-weight) suggest little biomagnification has occurred at these trophic levels. Mercury concentrations in epaxial muscle of largemouth bass (concentrations ranged from 0.86 mg/kg to 1.6 mg/kg wet-weight) are at levels of concern for human health, and fish consumption advisories are posted at the Reservoir. Food web results indicate that significant biomagnification is occurring at higher trophic levels within the foodweb. Current studies suggest that elevated mercury concentrations in largemouth bass are strongly linked to the life history characteristics of the fish. Close

• 2232. [Article] A hierarchical stream habitat classification system: development and demonstration

  Classification of Streams and stream habitats is useful for research involving establishment of monitoring stations, determining local impacts of land use practices, generalization from site-specific data, ...

  Citation × Citation Citation Abstract Copy Title: A hierarchical stream habitat classification system: development and demonstration Author: Frissell, Christopher A. Classification of Streams and stream habitats is useful for research involving establishment of monitoring stations, determining local impacts of land use practices, generalization from site-specific data, and assessment of basin-wide, cumulative impacts of human activities on streams and their biota. This thesis presents a framework for a hierarchical classification system, entailing an organized view of spatial and temporal variation between and within stream systems. Stream habitat systems, defined and classified on several spatio-temporal scales, are associated with watershed geomorphic features and events. Variables selected for classification define relative long-term capacities of systems, not simply short-term states. Streams and their watershed environments are classified within the context of a regional biogeoclimatic classification. The framework is a perspective that should allow more systematic interpretation and description of watershed/stream relationships. The classification system was used to assess changes in stream habitat caused by logging and debris removal in a fourth-order stream in the High Cascades of Oregon. Habitat organization, trout density, and habitat use were compared in logged (clear-cut, 1962) and forested stream sections in the same stream segment. The hierarchical classification system allowed pool/riffle habitats to he related to the geomorphic history of different stream reaches. Due to the presence of large debris dams and abundant woody debris, forested reaches varied in morphology and encompassed a wide array of pool/riffle habitats, including debris-created pools and side channels. Clear-cut reaches were relatively homogeneous, and were dominated by boulder-formed habitats. Although trout density was highly reach-specific, total density of the forested section was 40% greater than that of the clear-cut section. The smallest size class was absent and large (>14 cm) individuals were uncommon in clear-cut reaches. A regression model showed that most of the variation among reaches in trout density was related to the relative area comprised of six key pool/riffle types. The habitat classification system proved useful in demonstrating that the forested stream section, because of its diversity of pool/riffle types, may best provide the range of habitats required by all size classes through changing streamflow conditions. Title: A hierarchical stream habitat classification system: development and demonstration Author: Frissell, Christopher A. Classification of Streams and stream habitats is useful for research involving establishment of monitoring stations, determining local impacts of land use practices, generalization from site-specific data, and assessment of basin-wide, cumulative impacts of human activities on streams and their biota. This thesis presents a framework for a hierarchical classification system, entailing an organized view of spatial and temporal variation between and within stream systems. Stream habitat systems, defined and classified on several spatio-temporal scales, are associated with watershed geomorphic features and events. Variables selected for classification define relative long-term capacities of systems, not simply short-term states. Streams and their watershed environments are classified within the context of a regional biogeoclimatic classification. The framework is a perspective that should allow more systematic interpretation and description of watershed/stream relationships. The classification system was used to assess changes in stream habitat caused by logging and debris removal in a fourth-order stream in the High Cascades of Oregon. Habitat organization, trout density, and habitat use were compared in logged (clear-cut, 1962) and forested stream sections in the same stream segment. The hierarchical classification system allowed pool/riffle habitats to he related to the geomorphic history of different stream reaches. Due to the presence of large debris dams and abundant woody debris, forested reaches varied in morphology and encompassed a wide array of pool/riffle habitats, including debris-created pools and side channels. Clear-cut reaches were relatively homogeneous, and were dominated by boulder-formed habitats. Although trout density was highly reach-specific, total density of the forested section was 40% greater than that of the clear-cut section. The smallest size class was absent and large (>14 cm) individuals were uncommon in clear-cut reaches. A regression model showed that most of the variation among reaches in trout density was related to the relative area comprised of six key pool/riffle types. The habitat classification system proved useful in demonstrating that the forested stream section, because of its diversity of pool/riffle types, may best provide the range of habitats required by all size classes through changing streamflow conditions. Close

• 2233. [Article] Cereal stem moth, Ochsenheimeria vacculella Fischer von Röslerstamm (Lepidoptera : Ochsenheimeriidae) : field biology and larval development on selected grasses and cereals in Western Oregon

  The seasonal life history of the cereal stem moth (CSM), Ochsenheimeria vacculella Fischer von Roslerstamm, (Lepidoptera : Ochsenheimeriidae) was investigated in a commercial field of annual ryegrass in ...

  Citation × Citation Citation Abstract Copy Title: Cereal stem moth, Ochsenheimeria vacculella Fischer von Röslerstamm (Lepidoptera : Ochsenheimeriidae) : field biology and larval development on selected grasses and cereals in Western Oregon Author: Panasahatham, Sarote The seasonal life history of the cereal stem moth (CSM), Ochsenheimeria vacculella Fischer von Roslerstamm, (Lepidoptera : Ochsenheimeriidae) was investigated in a commercial field of annual ryegrass in the Willamette Valley, OR from January 1993 to August 1994. Phenology of life stages, effect of temperature on eclosion, and development of larvae on potential hosts of economic importantce were also studied. First records of parasitization and effects of cultural practices on this potential pest in annual ryegrass were reported. CSM is a recent introduction to North America from a monobasic family of the Palearctic region. Its life cycle is functionally univoltine in commercial ryegrass seed fields. Eggs are characteristically deposited on interior wooden walls, ceilings and straw bales or piles in outbuildings from June through September. Eclosion occurs bimodally with approximately fifty percent of current season eggs hatching in late June and July. The remainder overwinter and hatch in February and March. Larvae ballooned from oviposition sites to potential hosts and were found in annual ryegrass from February to early June. First instar larvae typically mine leaves; later stadia are stem borers. Variance to mean ratios of larvae sampled in annual ryegrass described a clumped population. Pupation occurred from late May to early July. The pupa was enclosed in a flimsy cocoon usually located on the inside of a flag leaf's sheath. Shortly after emergence in early June and July, adults fly to outbuildings preferentially remaining within those where grass straw has been stored. Migration from the field and subsequent flight, copulation and oviposition within buildings occurred only on bright days from approximately noon to 4:30 pm (PDT) through September at which time most adults have died. Two species of larval parasitoids in the Eulophidae and Ichneumonidae were very abundant in the annual ryegrass field under study during June and July 1994. Their combined parasitization rate of CSM larvae exceeded ninety percent. A frequency distribution of head capsule widths indicates CSM larvae probably develop through five instars. However, inter-instar ratios of head capsule widths did not conform to Dyar's hypothesis. Eggs deposited by females collected in the field and allowed to oviposit in the laboratory did not hatch at either room temperature or 6°C. However, cohorts of eggs hatched readily during incubation at either 10° or 14°C when observed after two and three months exposure. Nine varieties of six commercially important species of grasses and cereals were evaluated for suitability as larval hosts. Annual ryegrass, Lolium multiflorum Lam., consistently supported the greatest population densities in the field and resulted in greatest survival of larvae in laboratory and greenhouse tests. Removal of annual ryegrass foliage in plots during late winter or early spring to simulate the effect of sheep grazing significantly reduced subsequent larval populations relative to plots without vegetation removal. Title: Cereal stem moth, Ochsenheimeria vacculella Fischer von Röslerstamm (Lepidoptera : Ochsenheimeriidae) : field biology and larval development on selected grasses and cereals in Western Oregon Author: Panasahatham, Sarote The seasonal life history of the cereal stem moth (CSM), Ochsenheimeria vacculella Fischer von Roslerstamm, (Lepidoptera : Ochsenheimeriidae) was investigated in a commercial field of annual ryegrass in the Willamette Valley, OR from January 1993 to August 1994. Phenology of life stages, effect of temperature on eclosion, and development of larvae on potential hosts of economic importantce were also studied. First records of parasitization and effects of cultural practices on this potential pest in annual ryegrass were reported. CSM is a recent introduction to North America from a monobasic family of the Palearctic region. Its life cycle is functionally univoltine in commercial ryegrass seed fields. Eggs are characteristically deposited on interior wooden walls, ceilings and straw bales or piles in outbuildings from June through September. Eclosion occurs bimodally with approximately fifty percent of current season eggs hatching in late June and July. The remainder overwinter and hatch in February and March. Larvae ballooned from oviposition sites to potential hosts and were found in annual ryegrass from February to early June. First instar larvae typically mine leaves; later stadia are stem borers. Variance to mean ratios of larvae sampled in annual ryegrass described a clumped population. Pupation occurred from late May to early July. The pupa was enclosed in a flimsy cocoon usually located on the inside of a flag leaf's sheath. Shortly after emergence in early June and July, adults fly to outbuildings preferentially remaining within those where grass straw has been stored. Migration from the field and subsequent flight, copulation and oviposition within buildings occurred only on bright days from approximately noon to 4:30 pm (PDT) through September at which time most adults have died. Two species of larval parasitoids in the Eulophidae and Ichneumonidae were very abundant in the annual ryegrass field under study during June and July 1994. Their combined parasitization rate of CSM larvae exceeded ninety percent. A frequency distribution of head capsule widths indicates CSM larvae probably develop through five instars. However, inter-instar ratios of head capsule widths did not conform to Dyar's hypothesis. Eggs deposited by females collected in the field and allowed to oviposit in the laboratory did not hatch at either room temperature or 6°C. However, cohorts of eggs hatched readily during incubation at either 10° or 14°C when observed after two and three months exposure. Nine varieties of six commercially important species of grasses and cereals were evaluated for suitability as larval hosts. Annual ryegrass, Lolium multiflorum Lam., consistently supported the greatest population densities in the field and resulted in greatest survival of larvae in laboratory and greenhouse tests. Removal of annual ryegrass foliage in plots during late winter or early spring to simulate the effect of sheep grazing significantly reduced subsequent larval populations relative to plots without vegetation removal. Close

• 2234. [Article] Patterns and dynamics of context-dependency in the marine rocky intertidal

  As ecologists are being called upon to predict the consequences of human perturbations to natural communities, an important goal is to understand what factors drive variability or consistency in nature. In ...

  Citation × Citation Citation Abstract Copy Title: Patterns and dynamics of context-dependency in the marine rocky intertidal Author: Berlow, Eric Layani As ecologists are being called upon to predict the consequences of human perturbations to natural communities, an important goal is to understand what factors drive variability or consistency in nature. In the rocky intertidal of San Juan Island, Washington, a comparative experimental approach was used to investigate spatial and temporal variation in community organization. The effect of predation on B. glandula varied dramatically over small spatial scales between microhabitats but was remarkably consistent over time withing a given microhabitat. The effects of predation on S. cariosus varied over time within the same microhabitat. By repeating previous landmark experiments at our study site, and replicating these experiments across microhabitats, the domain of applicability of previous experimental information was greatly expanded. In an early successional assemblage on the Oregon coast, I tested the hypothesis that, when the direct effect of one species on another increases in relative strength, its total effect (direct + indirect) is less variable or conditional than if the link between those species is weak. The effect of strong predation by whelks was less sensitive to the presence of additional species and more consistently dampened natural variation between experimental starting dates and between individual replicates within a given experiment. In contrast, the outcome of weak predation was more spatially and temporally variable in sign, and whether it magnified or dampened differences between individual replicates varied between experiments. Consequently the mean total effect of weak predation generally did not differ significantly from zero. However, in some cases, the range of variation (both within and between experiments) in the effect of weak predation exceeded the magnitude of the strongest total effect observed. Longer term results of the experiments on the Oregon coast examined the role of historic factors in influencing the degree to which successional paths are canalized and repeatable or contingent and variable. Succession in mid-intertidal patches in the mussel bed displayed complex patterns of historic effects that varied between species and between different stages of succession. Despite its potential complexity, this system exhibited some consistent and repeatable patterns of succession. Some important canalizing, or noise-dampening forces in this system included: 1) physiological and life-history constraints, 2) compensatory responses of functionally redundant species, and 3) strong interactions between species. Title: Patterns and dynamics of context-dependency in the marine rocky intertidal Author: Berlow, Eric Layani As ecologists are being called upon to predict the consequences of human perturbations to natural communities, an important goal is to understand what factors drive variability or consistency in nature. In the rocky intertidal of San Juan Island, Washington, a comparative experimental approach was used to investigate spatial and temporal variation in community organization. The effect of predation on B. glandula varied dramatically over small spatial scales between microhabitats but was remarkably consistent over time withing a given microhabitat. The effects of predation on S. cariosus varied over time within the same microhabitat. By repeating previous landmark experiments at our study site, and replicating these experiments across microhabitats, the domain of applicability of previous experimental information was greatly expanded. In an early successional assemblage on the Oregon coast, I tested the hypothesis that, when the direct effect of one species on another increases in relative strength, its total effect (direct + indirect) is less variable or conditional than if the link between those species is weak. The effect of strong predation by whelks was less sensitive to the presence of additional species and more consistently dampened natural variation between experimental starting dates and between individual replicates within a given experiment. In contrast, the outcome of weak predation was more spatially and temporally variable in sign, and whether it magnified or dampened differences between individual replicates varied between experiments. Consequently the mean total effect of weak predation generally did not differ significantly from zero. However, in some cases, the range of variation (both within and between experiments) in the effect of weak predation exceeded the magnitude of the strongest total effect observed. Longer term results of the experiments on the Oregon coast examined the role of historic factors in influencing the degree to which successional paths are canalized and repeatable or contingent and variable. Succession in mid-intertidal patches in the mussel bed displayed complex patterns of historic effects that varied between species and between different stages of succession. Despite its potential complexity, this system exhibited some consistent and repeatable patterns of succession. Some important canalizing, or noise-dampening forces in this system included: 1) physiological and life-history constraints, 2) compensatory responses of functionally redundant species, and 3) strong interactions between species. Close

• 2235. [Article] Age, growth, and diet of fish in the Waldo Lake natural-cultural system

  Waldo Lake, located in the Oregon Cascades, is considered to be one of the most dilute lakes in the world. Even with very low nutrient concentrations and sparse populations of zooplankton, introduced fish ...

  Citation × Citation Citation Abstract Copy Title: Age, growth, and diet of fish in the Waldo Lake natural-cultural system Author: Swets, Nicola L. Waldo Lake, located in the Oregon Cascades, is considered to be one of the most dilute lakes in the world. Even with very low nutrient concentrations and sparse populations of zooplankton, introduced fish in the lake are large in size and in good condition when compared to fish from other lakes. Fish were originally stocked in Waldo Lake in the late 1800's. The Oregon Department of Fish and Wildlife began stocking in the late 1930's and continued stocking until 1991. Species existing in Waldo Lake today include brook trout, rainbow trout, and kokanee salmon. The overall objective of this thesis was to increase the understanding of the interrelationships that affect the age, growth, and diet of fish in Waldo Lake. The specific objectives were to summarize and synthesize available information on the substrate, climate, water, and biota of the Waldo Lake Basin; describe the cultural history and current cultural values of the Waldo Lake Basin; determine the age, growth, length, weight, condition, diet, and reproduction of introduced fish species in Waldo Lake; interrelate the above information to show how these components of the natural-cultural system are related. Fish were collected one week per month from early June through mid-October in 1992 and 1993. Variable mesh experimental gillnets set in nearshore areas were used to capture fish in 1992. During the 1993 sampling period, experimental gillnets and trapnets were set in the nearshore areas of the lake. Relative age specific growth rates of brook trout in Waldo Lake are comparable to brook trout growth rates in other lakes. Brook trout growth rates generally decreased with age, however, there were no significant differences in the growth rate of each age class between 1991 and 1993. The condition of brook trout in Waldo Lake is also comparable to brook trout in other lakes. The same is true for rainbow trout and kokanee salmon. Fish in Waldo Lake are large in size and in good condition due, in part, to the availability of benthic macroinvertebrates. Taxa found in stomach contents of fish captured in Waldo Lake consisted primarily of aquatic benthic macroinvertebrates, but terrestrial vertebrates and vertebrates, although infrequently consumed, were also part of the total diet. Rainbow trout in Waldo Lake consumed primarily chironomidae larvae and pupae although odonata larvae, ephemeroptera larvae, and amphipods were also consumed. Kokanee salmon fed almost exclusively on chironomid larvae although small numbers of ephemeroptera larvae, odonata larvae, and coleoptera were also consumed. The most important macroinvertebrate taxon consumed by Waldo Lake brook trout was chironomid larvae and pupae, although other species also were important. The diet of Waldo Lake brook trout varied in a complex way that appeared to be related to the relative abundance of macroinvertebrate taxa, feeding location in the lake, and time of year. Brook trout diet also varied by size class. The components of the Waldo Lake natural-cultural system are complexly interrelated and the nature of these relationships are constantly changing. Each component in some way affects and is, in turn, affected by each of the other components. Changes in some components, such as substrate, affect other components along geologic time scales. Other components, such human culture and biota, may change rapidly within a decade. The capacity of natural-cultural systems, such as Waldo Lake, to change over time makes it possible to view the present state of the system only as a snapshot in time. This dynamic nature of the Waldo Lake natural-cultural system is not unique to Waldo Lake, but is expressed in all natural- cultural systems. Title: Age, growth, and diet of fish in the Waldo Lake natural-cultural system Author: Swets, Nicola L. Waldo Lake, located in the Oregon Cascades, is considered to be one of the most dilute lakes in the world. Even with very low nutrient concentrations and sparse populations of zooplankton, introduced fish in the lake are large in size and in good condition when compared to fish from other lakes. Fish were originally stocked in Waldo Lake in the late 1800's. The Oregon Department of Fish and Wildlife began stocking in the late 1930's and continued stocking until 1991. Species existing in Waldo Lake today include brook trout, rainbow trout, and kokanee salmon. The overall objective of this thesis was to increase the understanding of the interrelationships that affect the age, growth, and diet of fish in Waldo Lake. The specific objectives were to summarize and synthesize available information on the substrate, climate, water, and biota of the Waldo Lake Basin; describe the cultural history and current cultural values of the Waldo Lake Basin; determine the age, growth, length, weight, condition, diet, and reproduction of introduced fish species in Waldo Lake; interrelate the above information to show how these components of the natural-cultural system are related. Fish were collected one week per month from early June through mid-October in 1992 and 1993. Variable mesh experimental gillnets set in nearshore areas were used to capture fish in 1992. During the 1993 sampling period, experimental gillnets and trapnets were set in the nearshore areas of the lake. Relative age specific growth rates of brook trout in Waldo Lake are comparable to brook trout growth rates in other lakes. Brook trout growth rates generally decreased with age, however, there were no significant differences in the growth rate of each age class between 1991 and 1993. The condition of brook trout in Waldo Lake is also comparable to brook trout in other lakes. The same is true for rainbow trout and kokanee salmon. Fish in Waldo Lake are large in size and in good condition due, in part, to the availability of benthic macroinvertebrates. Taxa found in stomach contents of fish captured in Waldo Lake consisted primarily of aquatic benthic macroinvertebrates, but terrestrial vertebrates and vertebrates, although infrequently consumed, were also part of the total diet. Rainbow trout in Waldo Lake consumed primarily chironomidae larvae and pupae although odonata larvae, ephemeroptera larvae, and amphipods were also consumed. Kokanee salmon fed almost exclusively on chironomid larvae although small numbers of ephemeroptera larvae, odonata larvae, and coleoptera were also consumed. The most important macroinvertebrate taxon consumed by Waldo Lake brook trout was chironomid larvae and pupae, although other species also were important. The diet of Waldo Lake brook trout varied in a complex way that appeared to be related to the relative abundance of macroinvertebrate taxa, feeding location in the lake, and time of year. Brook trout diet also varied by size class. The components of the Waldo Lake natural-cultural system are complexly interrelated and the nature of these relationships are constantly changing. Each component in some way affects and is, in turn, affected by each of the other components. Changes in some components, such as substrate, affect other components along geologic time scales. Other components, such human culture and biota, may change rapidly within a decade. The capacity of natural-cultural systems, such as Waldo Lake, to change over time makes it possible to view the present state of the system only as a snapshot in time. This dynamic nature of the Waldo Lake natural-cultural system is not unique to Waldo Lake, but is expressed in all natural- cultural systems. Close

• 2236. [Article] The development and analysis of sequence-based DNA markers in sunflower for DNA fingerprinting and candidate gene analysis

  Molecular DNA markers have become widely used in all areas of genetic research. The objectives of this thesis were to develop polymorphic markers in sunflower and utilize the markers for genetic and candidate ...

  Citation × Citation Citation Abstract Copy Title: The development and analysis of sequence-based DNA markers in sunflower for DNA fingerprinting and candidate gene analysis Author: Hongtrakul, Vipa Molecular DNA markers have become widely used in all areas of genetic research. The objectives of this thesis were to develop polymorphic markers in sunflower and utilize the markers for genetic and candidate gene analyses. Amplified fragment length polymorphism (AFLP) markers were used to estimate genetic similarities and assess the genetic diversity among 24 public oilseed inbred lines of sunflower (Helianthus annuus L.). A total of 359 AFLP markers were scored by using six AFLP primer combinations. Genetic similarities ranged from 0.70 to 0.91, polymorphism rate ranged from 7 to 24%, and polymorphic information contents (PICs) ranged from 0.0 to 0.5. Principal coordinate and cluster analysis separated the lines into two groups, B-lines and R-lines, illustrating breeding history, basic heterotic pattern and the widespread practice of using each group to develop new lines. Δ9 stearoyl-ACP desaturase (SAD) and Δl2 oleate desaturase (OLD) cDNAs were cloned and sequenced. DNA fragment length polymorphism (DFLP), single strand conformational polymorphism (SSCP), and simple sequence repeat (SSR) markers were developed for the SAD6 and SAD17 genes among eight elite inbred lines. PICs for DFLP, SSCP, and SSR markers were 0.18, 0.37, and 0.30, respectively. Length variants were due to long monomeric repeats, insertions, and deletions in intron sequences, thereby producing polymorphic markers. OLD desaturates 18:1-PC (oleoyl phosphatidylcholine) to 18:2-PC, thereby converting oleic to linoleic acid. It is a likely candidate gene to be causing the high oleic phenotype in mutant sunflower. The expression of OLD7 in developing seeds was greatly reduced in mutant as opposed to wildtype backcross-derived lines. The restriction fragment length polymorphism (RFLP) patterns suggest that OLD7 is duplicated and rearranged in mutant lines. Utilizing sunflower SAD gene sequences and 27 inbred lines, intron fragment length polymorphism (IFLP) markers were developed for automated genotyping. These IFLP markers with ~470 to ~850 bp in length had a mean PIC score of 0.414, versus 0.336 for DFLP markers, and 0.582 for SSCP markers. One and two nucleotide length polymorphisms were reliably detected in PCR fragments up to ~150 and ~680 bp, respectively. Title: The development and analysis of sequence-based DNA markers in sunflower for DNA fingerprinting and candidate gene analysis Author: Hongtrakul, Vipa Molecular DNA markers have become widely used in all areas of genetic research. The objectives of this thesis were to develop polymorphic markers in sunflower and utilize the markers for genetic and candidate gene analyses. Amplified fragment length polymorphism (AFLP) markers were used to estimate genetic similarities and assess the genetic diversity among 24 public oilseed inbred lines of sunflower (Helianthus annuus L.). A total of 359 AFLP markers were scored by using six AFLP primer combinations. Genetic similarities ranged from 0.70 to 0.91, polymorphism rate ranged from 7 to 24%, and polymorphic information contents (PICs) ranged from 0.0 to 0.5. Principal coordinate and cluster analysis separated the lines into two groups, B-lines and R-lines, illustrating breeding history, basic heterotic pattern and the widespread practice of using each group to develop new lines. Δ9 stearoyl-ACP desaturase (SAD) and Δl2 oleate desaturase (OLD) cDNAs were cloned and sequenced. DNA fragment length polymorphism (DFLP), single strand conformational polymorphism (SSCP), and simple sequence repeat (SSR) markers were developed for the SAD6 and SAD17 genes among eight elite inbred lines. PICs for DFLP, SSCP, and SSR markers were 0.18, 0.37, and 0.30, respectively. Length variants were due to long monomeric repeats, insertions, and deletions in intron sequences, thereby producing polymorphic markers. OLD desaturates 18:1-PC (oleoyl phosphatidylcholine) to 18:2-PC, thereby converting oleic to linoleic acid. It is a likely candidate gene to be causing the high oleic phenotype in mutant sunflower. The expression of OLD7 in developing seeds was greatly reduced in mutant as opposed to wildtype backcross-derived lines. The restriction fragment length polymorphism (RFLP) patterns suggest that OLD7 is duplicated and rearranged in mutant lines. Utilizing sunflower SAD gene sequences and 27 inbred lines, intron fragment length polymorphism (IFLP) markers were developed for automated genotyping. These IFLP markers with ~470 to ~850 bp in length had a mean PIC score of 0.414, versus 0.336 for DFLP markers, and 0.582 for SSCP markers. One and two nucleotide length polymorphisms were reliably detected in PCR fragments up to ~150 and ~680 bp, respectively. Close

• 2237. [Article] Differential growth of roots and shoots of Douglas-fir (Pseudotsuga menziesii) seedlings infested with Cinara pseudotsugae, and population dynamics of a parasitoid wasp (Pauesia sp.) of C. pseudotsugae

  Aphids are a widespread family of plant pests, whose abilities to suppress shoot and root growth are well documented for many terrestrial plants. Only a few studies have been conducted on conifer aphids ...

  Citation × Citation Citation Abstract Copy Title: Differential growth of roots and shoots of Douglas-fir (Pseudotsuga menziesii) seedlings infested with Cinara pseudotsugae, and population dynamics of a parasitoid wasp (Pauesia sp.) of C. pseudotsugae Author: Smith, Julia P. Aphids are a widespread family of plant pests, whose abilities to suppress shoot and root growth are well documented for many terrestrial plants. Only a few studies have been conducted on conifer aphids of the genus Cinara. Cinara pseudotsugae are known to attack Douglas-fir seedlings, an important crop in the Pacific Northwest. Douglas-fir are most susceptible to aphid damage as seedlings, especially in nurseries where conditions favor aphid outbreaks. A parasitoid wasp (Pauesia sp.) attacks C. pseudotsugae, and may be useful as a biological control agent. Studies of its natural history and host interactions are needed to assess its potential as a bio-control agent. This study examined the effects of an experimental range of aphid densities on the growth of total shoot and root volume and biomass and shoot morphology of Douglas-fir seedlings. Eighteen-week tests explored short term effects of different aphid feeding intensities in both the greenhouse and field. Long term effects were tested by exposing greenhouse seedlings to 16 months of aphid feeding. The ability of the plants to recover was tested by allowing one set of seedlings to grow aphid free for one year, after being exposed to aphid feeding for 18 weeks. The success rate of parasitoids over an 18 week period was compared to aphid density in both greenhouse and field tests. Increasing aphid destiny was significantly related to decreasing root and shoot dry weights in greenhouse tests. Growth suppression increased slightly during the second year of testing, regardless of whether or not aphid feeding continued. The results for root and shoot volumes were highly variable. However, root tissue density was significantly reduced after the second year of testing. Few shoot characteristics showed consistently significant aphid effects among the trials. Stem diameter and height decreased and needle density of new buds increased significantly with aphid feeding in most tests. Root and shoot growth of field plants did not show any significant aphid effects. Percentage of parasitoid success was independent of aphid density except at the lowest aphid densities. There was a block effect on parasitoid success in the field test, that may have been a result of varying environmental conditions. These results indicate that even short term aphid feeding can have long lasting effects on plant growth and structure. The effect on shoot and root growth was small, but there were no signs of recovery. The long term effects of the reduced root tissue density on Douglas-fir is unknown. Title: Differential growth of roots and shoots of Douglas-fir (Pseudotsuga menziesii) seedlings infested with Cinara pseudotsugae, and population dynamics of a parasitoid wasp (Pauesia sp.) of C. pseudotsugae Author: Smith, Julia P. Aphids are a widespread family of plant pests, whose abilities to suppress shoot and root growth are well documented for many terrestrial plants. Only a few studies have been conducted on conifer aphids of the genus Cinara. Cinara pseudotsugae are known to attack Douglas-fir seedlings, an important crop in the Pacific Northwest. Douglas-fir are most susceptible to aphid damage as seedlings, especially in nurseries where conditions favor aphid outbreaks. A parasitoid wasp (Pauesia sp.) attacks C. pseudotsugae, and may be useful as a biological control agent. Studies of its natural history and host interactions are needed to assess its potential as a bio-control agent. This study examined the effects of an experimental range of aphid densities on the growth of total shoot and root volume and biomass and shoot morphology of Douglas-fir seedlings. Eighteen-week tests explored short term effects of different aphid feeding intensities in both the greenhouse and field. Long term effects were tested by exposing greenhouse seedlings to 16 months of aphid feeding. The ability of the plants to recover was tested by allowing one set of seedlings to grow aphid free for one year, after being exposed to aphid feeding for 18 weeks. The success rate of parasitoids over an 18 week period was compared to aphid density in both greenhouse and field tests. Increasing aphid destiny was significantly related to decreasing root and shoot dry weights in greenhouse tests. Growth suppression increased slightly during the second year of testing, regardless of whether or not aphid feeding continued. The results for root and shoot volumes were highly variable. However, root tissue density was significantly reduced after the second year of testing. Few shoot characteristics showed consistently significant aphid effects among the trials. Stem diameter and height decreased and needle density of new buds increased significantly with aphid feeding in most tests. Root and shoot growth of field plants did not show any significant aphid effects. Percentage of parasitoid success was independent of aphid density except at the lowest aphid densities. There was a block effect on parasitoid success in the field test, that may have been a result of varying environmental conditions. These results indicate that even short term aphid feeding can have long lasting effects on plant growth and structure. The effect on shoot and root growth was small, but there were no signs of recovery. The long term effects of the reduced root tissue density on Douglas-fir is unknown. Close

• 2238. [Article] Further Optimization of Controlled Depuration for Eliminating Vibrio parahaemolyticus from Raw Oysters for Safe Consumption

  Vibrio parahaemolyticus infections in the United Stated have been linked to consumption of raw shellfish, particularly oysters, with symptoms of headache, abdominal pain, nausea, diarrhea, vomiting. Depuration, ...

  Citation × Citation Citation Abstract Copy Title: Further Optimization of Controlled Depuration for Eliminating Vibrio parahaemolyticus from Raw Oysters for Safe Consumption Author: Ming, Ziwen Vibrio parahaemolyticus infections in the United Stated have been linked to consumption of raw shellfish, particularly oysters, with symptoms of headache, abdominal pain, nausea, diarrhea, vomiting. Depuration, as a post-harvest process, has a long history of being applied in shellfish industry to reduce sewage bacteria. In order to reduce the risks of V. parahaemolyticus infection associated with raw oyster consumption, FDA (2015) requires that post-harvest processes reduce V. parahaemolyticus and V. vulnificus to non-detectable levels (<30 MPN/g) and achieve a 3.52 log reduction. Previous investigations have indicated that a refrigerated seawater depuration process at 12.5°C could significantly reduce V. parahaemolyticus contamination in Pacific oysters; however, further optimization is necessary to achieve the regulatory target of >3.52 log MPN/g. The aim of this study was to investigate several factors, including flow rate and feeding status, to improve the efficacy of depuration in decreasing V. parahaemolyticus in oysters. The long-term goal for this research is adoption of depuration by the shellfish industry to produce safe oysters for raw consumption. Pacific oysters (Crassostrea gigas; n = 35 per trial) were inoculated with a cocktail of V. parahaemolyticus (10290, 10292,10293, BE 98-2029, and 027-1c1) in freshly prepared artificial seawater (70 L). Depuration was conducted on inoculated oysters with flow rates of 15, 20, 25 and 35 L/min at 12.5°C for up to 5 days. V. parahaemolyticus contamination was determined using a three-tube most probable number (MPN) method. The efficacy of microbial reductions of V. parahaemolyticus was significantly enhanced when the flow rate increased from 15 to 35 L/min. Depuration with a lower flow rate (15 L/min) for 5 days resulted in 2.39 log (MPN/g) reduction of V. parahaemolyticus in oysters, while depuration with higher flow rates of 20 and 25 L/min reached 2.73 and 2.80 log (MPN/g) reductions, respectively. Further increase in flow rate to 35 L/min resulted in an average reduction of 3.39 log MPN/g of V. parahaemolyticus in oysters after 5 days. These results suggest that depuration efficacy can be enhanced by further increasing the flow rate of the system. Studies of application of algae treatment in oyster depuration revealed that addition of algae mixture in artificial seawater (ASW) for depuration did not significantly impact the efficacy of depuration for reducing V. parahaemolyticus populations. Oysters inoculated with the V. parahaemolyticus cocktail were subjected to depuration with and without feeding (algae=0.036 ml/gram of oyster) for 6 days at 12.5°C with water ratio of 1:2. Oysters (n = 5) were analyzed for V. parahaemolyticus using a three-tube most probable number (MPN) method after 0, 1, 3, 5, and 6 days of depuration. Depuration over 6 days achieved average V. parahaemolyticus reductions of 2.75 log MPN/g and 3.03 log MPN/g in the fed and unfed systems, respectively. The lack of impact of feeding status on the efficacy of depuration provides the oyster industry with the flexibility to utilize fed or unfed conditions to apply in depuration process. In these studies, only the factor of flow rate had a positive impact on reduction of V. parahaemolyticus. However, neither flow rate nor feeding treatments were able to achieve 3.52 MPN/g reduction of V. parahaemolyticus. Further optimization of depuration is necessary to achieve the regulatory target for V. parahaemolyticus decontamination in raw oysters. Title: Further Optimization of Controlled Depuration for Eliminating Vibrio parahaemolyticus from Raw Oysters for Safe Consumption Author: Ming, Ziwen Vibrio parahaemolyticus infections in the United Stated have been linked to consumption of raw shellfish, particularly oysters, with symptoms of headache, abdominal pain, nausea, diarrhea, vomiting. Depuration, as a post-harvest process, has a long history of being applied in shellfish industry to reduce sewage bacteria. In order to reduce the risks of V. parahaemolyticus infection associated with raw oyster consumption, FDA (2015) requires that post-harvest processes reduce V. parahaemolyticus and V. vulnificus to non-detectable levels (<30 MPN/g) and achieve a 3.52 log reduction. Previous investigations have indicated that a refrigerated seawater depuration process at 12.5°C could significantly reduce V. parahaemolyticus contamination in Pacific oysters; however, further optimization is necessary to achieve the regulatory target of >3.52 log MPN/g. The aim of this study was to investigate several factors, including flow rate and feeding status, to improve the efficacy of depuration in decreasing V. parahaemolyticus in oysters. The long-term goal for this research is adoption of depuration by the shellfish industry to produce safe oysters for raw consumption. Pacific oysters (Crassostrea gigas; n = 35 per trial) were inoculated with a cocktail of V. parahaemolyticus (10290, 10292,10293, BE 98-2029, and 027-1c1) in freshly prepared artificial seawater (70 L). Depuration was conducted on inoculated oysters with flow rates of 15, 20, 25 and 35 L/min at 12.5°C for up to 5 days. V. parahaemolyticus contamination was determined using a three-tube most probable number (MPN) method. The efficacy of microbial reductions of V. parahaemolyticus was significantly enhanced when the flow rate increased from 15 to 35 L/min. Depuration with a lower flow rate (15 L/min) for 5 days resulted in 2.39 log (MPN/g) reduction of V. parahaemolyticus in oysters, while depuration with higher flow rates of 20 and 25 L/min reached 2.73 and 2.80 log (MPN/g) reductions, respectively. Further increase in flow rate to 35 L/min resulted in an average reduction of 3.39 log MPN/g of V. parahaemolyticus in oysters after 5 days. These results suggest that depuration efficacy can be enhanced by further increasing the flow rate of the system. Studies of application of algae treatment in oyster depuration revealed that addition of algae mixture in artificial seawater (ASW) for depuration did not significantly impact the efficacy of depuration for reducing V. parahaemolyticus populations. Oysters inoculated with the V. parahaemolyticus cocktail were subjected to depuration with and without feeding (algae=0.036 ml/gram of oyster) for 6 days at 12.5°C with water ratio of 1:2. Oysters (n = 5) were analyzed for V. parahaemolyticus using a three-tube most probable number (MPN) method after 0, 1, 3, 5, and 6 days of depuration. Depuration over 6 days achieved average V. parahaemolyticus reductions of 2.75 log MPN/g and 3.03 log MPN/g in the fed and unfed systems, respectively. The lack of impact of feeding status on the efficacy of depuration provides the oyster industry with the flexibility to utilize fed or unfed conditions to apply in depuration process. In these studies, only the factor of flow rate had a positive impact on reduction of V. parahaemolyticus. However, neither flow rate nor feeding treatments were able to achieve 3.52 MPN/g reduction of V. parahaemolyticus. Further optimization of depuration is necessary to achieve the regulatory target for V. parahaemolyticus decontamination in raw oysters. Close

• 2239. [Article] Contribution to the biology of the albacore (Germo alalunga) of the Oregon coast and other parts of the North Pacific

  The temperate water fisheries for albacore in the North Pacific seem to exploit somewhat similar segments of the respective populations present in the various localities. It is clear that in most of the ...

  Citation × Citation Citation Abstract Copy Title: Contribution to the biology of the albacore (Germo alalunga) of the Oregon coast and other parts of the North Pacific Author: Brock, Vernon E., Oregon. Fish Commission The temperate water fisheries for albacore in the North Pacific seem to exploit somewhat similar segments of the respective populations present in the various localities. It is clear that in most of the exploited populations two or at most three year classes are highly dominant. In the California fishery from 1924 to 1928 the population segment exploited appears to have been composed, in the main, of only two year classes. The Oregon fishery likewise has drawn upon fish belonging largely to two year classes. The Oregon length-frequency measurements resemble very closely those from California. The range in lengths of Japanese albacore as well as the few modal groups present make it seem probable that only a few year classes were present in the Japanese landings. Although age readings by the use of vertebral rings as made by Japanese investigators are of doubtful accuracy, they show the presence of only three year classes, and only one of these in abundance. The lengths of the Japanese fish were similar to those landed in the American fisheries. Fish with ripening ova are not present in the Oregon fishery and have never been recorded from the California fishery. Kishinouye discovered no fish with maturing reproductive elements in Japanese waters. The fish landed from the small Hawaiian albacore fishery apparently do not share these characteristics. These fish are larger and evidently do possess ripening ova. Whether smaller immature fish similar to those taken in American and Japanese fisheries are also taken in the Hawaiian fishery is not known. While it is possible that fish are only caught at times when no ripening ova are present, it is more probable that the fish taken in both American and Japanese fisheries are actually immature and have never spawned. The available evidence, therefore, strongly suggests that only a few year classes are present in the temperate water fisheries for this species, and that these are immature. This may, at least in part, account for the history of instability shown by the California fishery and may cause a similar instability in the Oregon fishery. The populations exploited by the North Pacific albacore fisheries may represent three different stocks or races which center off the coasts of North America, Hawaii, and Japan. However, the existence of albacore in mid-Pacific at positions roughly midway between these three localities makes it appear possible that more or less intermingling may occur. Whether or not those fish occurring offshore represent wholesale migratory movements is unknown; but if so, that fact would inevitably force the study and conservation of this species to cover the entire North Pacific Basin. Title: Contribution to the biology of the albacore (Germo alalunga) of the Oregon coast and other parts of the North Pacific Author: Brock, Vernon E., Oregon. Fish Commission The temperate water fisheries for albacore in the North Pacific seem to exploit somewhat similar segments of the respective populations present in the various localities. It is clear that in most of the exploited populations two or at most three year classes are highly dominant. In the California fishery from 1924 to 1928 the population segment exploited appears to have been composed, in the main, of only two year classes. The Oregon fishery likewise has drawn upon fish belonging largely to two year classes. The Oregon length-frequency measurements resemble very closely those from California. The range in lengths of Japanese albacore as well as the few modal groups present make it seem probable that only a few year classes were present in the Japanese landings. Although age readings by the use of vertebral rings as made by Japanese investigators are of doubtful accuracy, they show the presence of only three year classes, and only one of these in abundance. The lengths of the Japanese fish were similar to those landed in the American fisheries. Fish with ripening ova are not present in the Oregon fishery and have never been recorded from the California fishery. Kishinouye discovered no fish with maturing reproductive elements in Japanese waters. The fish landed from the small Hawaiian albacore fishery apparently do not share these characteristics. These fish are larger and evidently do possess ripening ova. Whether smaller immature fish similar to those taken in American and Japanese fisheries are also taken in the Hawaiian fishery is not known. While it is possible that fish are only caught at times when no ripening ova are present, it is more probable that the fish taken in both American and Japanese fisheries are actually immature and have never spawned. The available evidence, therefore, strongly suggests that only a few year classes are present in the temperate water fisheries for this species, and that these are immature. This may, at least in part, account for the history of instability shown by the California fishery and may cause a similar instability in the Oregon fishery. The populations exploited by the North Pacific albacore fisheries may represent three different stocks or races which center off the coasts of North America, Hawaii, and Japan. However, the existence of albacore in mid-Pacific at positions roughly midway between these three localities makes it appear possible that more or less intermingling may occur. Whether or not those fish occurring offshore represent wholesale migratory movements is unknown; but if so, that fact would inevitably force the study and conservation of this species to cover the entire North Pacific Basin. Close

• 2240. [Article] The manganese and iron shuttle in a modern euxinic basin and implications for molybdenum cycling at euxinic ocean margins

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/chemical-geology...

  Citation × Citation Citation Abstract Copy Title: The manganese and iron shuttle in a modern euxinic basin and implications for molybdenum cycling at euxinic ocean margins Author: Sommer, Stefan, Scholz, Florian, McManus, James This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/chemical-geology/. Title: The manganese and iron shuttle in a modern euxinic basin and implications for molybdenum cycling at euxinic ocean margins Author: Sommer, Stefan, Scholz, Florian, McManus, James This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/chemical-geology/. Close