Alan Herlihy - Independent Researcher (original) (raw)
Papers by Alan Herlihy
Environmental Monitoring and Assessment
We analyzed data from 1138 wetland sites across the conterminous United States (US) as part of th... more We analyzed data from 1138 wetland sites across the conterminous United States (US) as part of the 2011 National Wetland Condition Assessment (NWCA) to investigate the response of indicators of wetland quality to indicators of human disturbance at regional and continental scales. The strength and nature of these relationships in wetlands have rarely been examined over large regions, due to the paucity of large-scale datasets. Wetland response indicators were a multimetric index of vegetation condition (VMMI), percent relative cover of alien plant species, soil lead and phosphorus, and water column total nitrogen and total phosphorus. Sitelevel disturbance indices were generated from field observations of disturbance types within a circular 140-m radius area around the sample point. Summary indices were calculated representing disturbances for ditching, damming, filling/erosion, hardening, vegetation replacement, and vegetation removal. Landscape-level disturbance associated with agricultural and urban land cover, roads, and human population were based on GIS data layers quantified in 200, 500, and 1000-m circular buffers around each sample point. Among these three buffer sizes, the landscape disturbance indicators were highly correlated and had similar relationships with the response indictors. Consequently, only the 1000-m buffer data were used for subsequent analyses. Disturbance-response models built using only landscape-or only site-level disturbance variables generally explained a small portion of the variance in the response variables (R 2 < 0.2), whereas models using both types of disturbance data were better at predicting wetland responses. The VMMI was the response variable with the strongest relationship to the disturbances assessed in the NWCA (national model R 2 = 0.251). National multiple regression models for the soil and water chemistry
Environmental Monitoring and Assessment
In 2011, the U.S. Environmental Protection Agency conducted the National Wetland Condition Assess... more In 2011, the U.S. Environmental Protection Agency conducted the National Wetland Condition Assessment (NWCA) as part of the National Aquatic Resource Survey (NARS) program to determine the condition of wetlands across the 48 contiguous states of the United States (US). Sites were selected using a generalized random tessellated stratified (GRTS) probability design. We quantified the types, extent, and magnitude of human activities as indicators of potential stress on a sample of 1138 wetland sites representing a target population of 251,546 km 2 of wetlands in the US. We used field observations of the presence and proximity of more than 50 predetermined types of human activity to define two types of indices that quantify human influences on wetlands. We grouped these
Environmental Monitoring and Assessment
stressors were associated with poor vegetation condition in one or another of the subpopulations.... more stressors were associated with poor vegetation condition in one or another of the subpopulations. Overall, hardening had the highest attributable and relative risks in the most different subpopulations. Attributable risks above 25% were observed for vegetation removal in the Coastal Plain, hardening and ditching in the West, and hardening in Estuarine Woody wetlands. Relative risks above 3 were noted for heavy metals and soil phosphorus in the Interior Plains, and vegetation removal, vegetation replacement, and damming in Estuarine Woody wetlands. Relative and attributable risk were added to the data analyses tools used in the NWCA to improve the ability of survey results to assist managers and policy makers in setting priorities based on conditions observed on the ground. These analyses provide useful information to both individual site managers and regional-national policy makers.
Environmental Monitoring and Assessment
One of the biggest challenges when conducting a continental-scale assessment of wetlands is setti... more One of the biggest challenges when conducting a continental-scale assessment of wetlands is setting appropriate expectations for the assessed sites. The challenge occurs for two reasons: (1) tremendous natural environmental heterogeneity exists within a continental landscape and (2) reference sites vary in quality both across and within major regions of the continent. We describe the process used to set reference expectations and define a disturbance gradient for the United States (US) Environmental Protection Agency's National Wetland Condition Assessment (NWCA). The NWCA employed a probability design and sampled 1138 wetland sites across the conterminous US to make an unbiased assessment of wetland condition. NWCA vegetation data were used to define 10 reporting groups based on ecoregion and wetland type that reduced the naturally occurring variation in wetland vegetation associated with continent-wide differences in biogeography. These reporting groups were used as a basis for defining quantitative criteria for least disturbed and most disturbed conditions and developing indices and thresholds for categories of ecological condition and disturbance. The NWCA vegetation assessment was based on a reference site approach, in which the least disturbed reference sites were used to establish benchmarks for assessing the condition of vegetation at other sites. Reference sites for each reporting group were identified by filtering NWCA sample data for disturbance using a series of abiotic variables. Ultimately, 277 least disturbed sites were used to set reference expectations for the NWCA. The NWCA provided a unique opportunity to improve our conceptual and technical understanding of how to best apply a reference condition approach to assessing wetlands across the US. These results will enhance the technical quality of future national assessments.
An improved macroinvertebrate multimetric index for the assessment of wadeable streams in the neotropical savanna
Ecological Indicators
A B S T R A C T Multimetric indices (MMIs) have been successfully used to assess ecological condi... more A B S T R A C T Multimetric indices (MMIs) have been successfully used to assess ecological conditions in freshwater ecosystems worldwide, and provide an important management tool especially in countries where biological indicators are fostered by environmental regulations. Nonetheless, for the neotropics, the few published papers are limited to small local scales and lack standardized sampling protocols. To fill the gaps left by previous studies, we propose a stream MMI that reflects anthropogenic impacts by using macroinvertebrate assemblage metrics from a data set of 190 sites collected from four hydrologic units in the Paraná and São Francisco River Basins, southeastern Brazil. Sites were selected through use of a probabilistic survey design allowing us to infer ecological condition to the total of 9432 kilometers of wadeable streams in the target population in the four hydrologic units. We used a filtering process to determine the least-and most-disturbed sites based on their water quality, physical habitat structure, and land use. To develop the MMI, we followed a stepwise procedure to screen our initial set of biological metrics for influence of natural variation, responsiveness and discriminance to disturbances, sampling variability, and redundancy. The final MMI is the sum of 7 scaled assemblage metrics describing different aspects of macroinvertebrate assemblage characteristics: Ephemeroptera richness, % Gastropoda individuals, Shannon-Wiener diversity index, % sensitive taxa richness, % scraper individuals, temporarily attached taxa richness, and gill respiration taxa richness. The MMI clearly distinguished the least-disturbed sites from the most-disturbed sites and showed a significant negative response to anthropogenic stressors. Of the total length of wadeable streams in the study area, 38%, 35%, and 27% were classified by the MMI as being in good, fair, and poor condition, respectively. By reducing the subjectivity of site selection, rigorously selecting the set of reference sites, and following a standardized metric screening method, we developed a robust MMI to assess and monitor ecological condition in neotropical savanna streams. This improved MMI provides an effective ecological tool to guide decision makers and managers in developing and implementing improved, cost-effective environmental policies, regulations, and monitoring of those systems.
Knowledge and Management of Aquatic Ecosystems
taxons indicateurs, traits de vie sont distingués par la localisation est-ouest, et par des facte... more taxons indicateurs, traits de vie sont distingués par la localisation est-ouest, et par des facteurs qui distinguent les cours d'eau de montagne, des rivières de basse altitude/plaines. Les groupes de l'est et de l'ouest qui ont les mêmes caractéristiques environnementales ont une composition en taxons définis à un niveau grossier très similaire et des traits de vie convergents. Les ordinations confirment que les schémas de composition faits à un niveau de résolution grossier des taxons et les traits des taxons ne reflètent plus des distinctions géographiques mais sont seulement reliés à des facteurs environnementaux non géographiques. Toutefois, les schémas de composition basés sur des traits, des taxons grossiers, et les macro-invertébrés identifiés au niveau le plus fin possible ont tous été corrélés avec les mêmes gradients environnementaux dominants non géographiques.
A synoptic survey of microbial respiration, organic matter decomposition, and carbon efflux in U.S. streams and rivers
Limnology and Oceanography
We analyzed ecoenzyme activities related to organic matter processing in 1879 streams and rivers ... more We analyzed ecoenzyme activities related to organic matter processing in 1879 streams and rivers across the continental U.S. as part of the USEPA's National Rivers and Streams Assessment. Ecoenzymatic stoichiometry was used to construct models for carbon use efficiency (CUE) and decomposition (). Microbial respiration (R) was estimated from sediment organic carbon stocks, CUE and . The streams and rivers were classified by size (headwaters: 1-order; streams: 2-3 order; small rivers: 4-5 order; big rivers 6-7 order; and great rivers ≥ 8 order) and condition class (least, intermediate and most disturbed), and grouped into nine ecoregions. There were ecoregion, stream size, and condition class effects for CUE, , and R, with R increasing from eastern ecoregions through the plains to the western ecoregions. CUE, , and R decreased with increasing streams size and increased with increasing disturbance. R, CUE, and were correlated with water and sediment chemistry; CUE and were also correlated with stream bed fine sediments; and CUE was further correlated with catchment land cover. R was extrapolated to ecoregional and national scales, and the results suggest that microbial assemblages account for 12% of the total CO outgassing, and nearly 50% of the aquatic metabolism C losses, from U.S. streams and rivers. Cumulative respiratory C losses increased from headwaters to small streams, then decreased with increasing stream size. This U-shaped respiration curve was not evident when streams were viewed by disturbance classes, suggesting that anthropogenic disturbances mask the expected organic matter processing signature of the river continuum.
Benthic microbial respiration in Appalachian Mountain, Piedmont, and Coastal Plains streams of the eastern U.S.A
Freshwater Biology, Jan 20, 2002
ABSTRACT
Bioscience, 2002
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
A null model for the expected macroinvertebrate assemblage in streams
Journal of the North American Benthological Society, Mar 1, 2005
Abstract Predictive models such as River InVertebrate Prediction And Classification System (RIVPA... more Abstract Predictive models such as River InVertebrate Prediction And Classification System (RIVPACS) and AUStralian RIVer Assessment System (AUSRIVAS) model the natural variation across geographic regions in the occurrences of macroinvertebrate taxa in data ...
Regional e Stimates O F a Cid M Ine D Rainage I Mpact on Streams in the M Id-Atlantic and Southeastern U Nited States
Water Air Soil Pollut, 1990
Effect of riparian areas on the ecological condition of small, perennial streams in agricultural landscapes of the Willamette Valley : research plan, June 1997
Hydrobiologia, Feb 29, 2004
We assessed the importance of spatial scales (catchment, stream network, and sample reach) on the... more We assessed the importance of spatial scales (catchment, stream network, and sample reach) on the effects of agricultural land-use on lotic diatom assemblages along a land-use gradient in the agricultural Willamette Valley Ecoregion of Oregon. Periphyton, water chemistry, and physical habitat conditions were characterized for 25 wadeable streams during a dry season (July to September, 1997). Additional water chemistry samples were collected in the following wet season (February 1998) to assess seasonal effects of land-use on stream water chemistry. Percent agricultural land-use in the study catchments ranged from 10% to 89% with an average of 52%. Partial canonical correspondence analysis (CCA) with the first axis constrained by % agricultural land-use showed that % agricultural land-use at 3 spatial scales explained between 3.7%-6.3% of variability in the diatom species dataset. Monte Carlo Permutation tests indicated that the variance explained by % agricultural land-use was only significant at the spatial scale of the stream network with 10-and 30-m band width (p < 0.05, 999 permutations). In addition to the effects of % agricultural land-use, partial CCAs with a forward selection option showed that water chemistry (e.g., SiO 2), reach-scale stream channel dimensions (e.g., width, depth, and slope), reach-scale in-stream habitats (substrates and filamentous algal cover in stream beds), and riparian vegetative buffer were all important with relation to diatom species assemblages. Percent of obligately nitrogen-heterotrophic taxa was the only diatom autecological metric that showed a significant but weak correlation with % agricultural land-use along the stream network (r = 0.50), but not at catchment or sample reach scale. Correlation between % agricultural land-use and water chemistry variables varied among the spatial scales and between seasons. Physical habitat variables (log 10 erodible substrate diameters and stream reach slope) were significantly correlated with % agricultural land-use along the stream network but not at catchment or sample reach scale. Our data suggest that spatial scales are important in assessing effects of land-use on stream conditions but the spatial scale effects may vary between seasons. Direct linkages between agricultural land-use and lotic diatom assemblages were weak during summer base-flow time regardless of the spatial scales. Summer sampling may underestimate the effects of catchment land-use on stream conditions in areas where seasonal patterns are so distinctive as in the Willamette Valley.
Fisheries, May 22, 2012
Patrones en la captura por unidad de esfuerzo de peces nativos y peces piscívoros foráneos en sie... more Patrones en la captura por unidad de esfuerzo de peces nativos y peces piscívoros foráneos en siete ríos del Pacífico Noroeste de los Estados Unidos de Norteamérica RESUMEN: es comúnmente aceptado que las especies no nativas o foráneas constituyen una amenaza para las comunidades biológicas locales; no obstante, resulta complicado separar el efecto que tienen estas especies invasoras frente a otras perturbaciones co-variantes. Se evaluó el efecto de los peces piscívoros foráneos sobre especies nativas en siete ríos del Pacífico Noroeste de los Estados Unidos de Norteamérica, mediante un muestreo al azar espacialmente balanceado en 20 localidades dentro de cada río. Los ríos carecían de drenajes importantes y los existentes, de haber alguno, cumplían con los estándares federales en cuanto a calidad del agua. En cada localidad de muestreo se llevó a cabo una colecta por medios eléctricos (electro-pesca) a una distancia equivalente a 50 veces el ancho del canal de inundación; todos los peces fueron identificados a nivel especie, medidos y devueltos vivos a los ríos (excepto aquellos especímenes destinados a museos). En casi todas las localidades de los siete ríos, se encontró que la captura por unidad de esfuerzo (CPUE) de las especies nativas de peces, varió de manera inversa con respecto a la CPUE de los peces piscívoros foráneos. En los dos ríos que estaban dominados mayormente por especies piscívoras, se colectaron especies nativas sólo en el 20-25% de las localidades. Se concluye que, al menos durante los periodos de flujo reducido en el verano, los peces piscívoros foráneos se relacionan con reducciones poblacionales de las especies nativas y constituyen una amenaza potencial a la persistencia de las especies locales.mentos relacionados a la liberación y los derechos de los animales, pueden tener consecuencias muy importantes para las pesquerías recreativas.
Using δ15N of Chironomidae to help assess lake condition and possible stressors in EPA’s National Lakes Assessment
ABSTRACT Background/Question/Methods As interest in continental-scale ecology increases to addres... more ABSTRACT Background/Question/Methods As interest in continental-scale ecology increases to address large-scale ecological problems, ecologists need indicators of complex processes that can be collected quickly at many sites across large areas. We are exploring the utility of stable isotopes from basal food chain organisms in providing information about nitrogen sources and processing at large scales within EPA’s water quality monitoring program. EPA has implemented the National Aquatic Resource Surveys, which use a probabilistic survey design to monitor 1000-2000 sites across the nation per water body type (Lake, River/Stream, Estuary, Wetland). While EPA measures many parameters during the one-day site visits, data on complex processes such as denitrification cannot be measured with such limited visit times. We are exploring the potential for δ15N measured in a family of insects, Chironomidae, which occupies several functional feeding groups in aquatic ecosystems to help classify lakes based on likely sources of or processes that affect nitrogen (N). In 2007, EPA conducted the National Lakes Assessment (NLA) on 1000 lakes, collecting composite benthic invertebrate samples from the littoral zone at 10 locations around each lake shoreline. After samples were counted and identified for biodiversity assessments, chironomids were separated, and then analyzed for δ15N. Results/Conclusions Chironomid δ15N values varied from -2 to 20 ‰ with a mean of 5.7 ‰ and were significantly higher in lakes with high nutrient concentrations. Since δ15N values can vary from both changes in N source (e.g. fertilizer vs. manure) and from N processing such as denitrification, we cannot determine a unique cause of δ15N enrichment. Instead, we used a decision tree approach to categorize lakes for likely N sources and whether denitrification is an important process in watershed N dynamics. Lakes with relatively high fertilizer loading (>10 kg/ha/yr) in the watershed generally had higher chironomid δ15N values suggesting higher nitrogen processing. We found that lakes with atmospheric nitrogen as their dominant loading source had low chironomid δ15N values resembling the low δ15N value of atmospheric deposition. For lakes with sewage or manure as the dominant N source in the watershed, chironomid δ15N values did not vary with watershed loading levels, and with a mean of 5.7 ‰, they did not reflect these relatively enriched δ15N sources. This decision tree approach in conjunction with other NLA data, chironomid δ15N values are promising to be highly useful indicators of denitrification and attributing N sources in national water quality monitoring efforts.
Http Dx Doi Org 10 1577 T05 312 1, Jan 9, 2011
An important issue surrounding assessment of riverine fish assemblages is the minimum amount of s... more An important issue surrounding assessment of riverine fish assemblages is the minimum amount of sampling distance needed to adequately determine biotic condition. Determining adequate sampling distance is important because sampling distance affects estimates of fish assemblage condition at both local and regional scales, and oversampling is costly. We examined the sampling distance question by sampling 45 raftable Oregon river reaches for an entire day and then assessing the minimum distance needed to obtain index of biotic integrity (IBI) scores in those reaches that varied by less than 10% from the 1-d samples. An electrofishing raft was used to collect fish, and physical and chemical habitats were sampled to aid in reach description. We found that a sampling distance equal to 50 times the mean wetted channel width, or a catch of more than 120 individuals, produced IBI scores that met our criteria.
Theory Can Help Structure Regression Models for Projecting Stream Conditions Under Alternative Land Use Scenarios
ABSTRACT
Regional Variation in Landscape Controls on the Width of Wadeable Streams Across the Conterminous United States
Agu Fall Meeting Abstracts, Dec 1, 2007
We examine regional variations in landscape controls on the width of wadeable streams across the ... more We examine regional variations in landscape controls on the width of wadeable streams across the conterminous United States using a unique dataset from the U.S. Environmental Protection Agency&amp;amp;amp;amp;#39;s (USEPA) Wadeable Streams Assessment (WSA). The WSA dataset includes a probability sample of over 1,300 randomly selected stream reaches (drawn from the 1:100,000 scale USGS digitized stream network) and over 500 hand-
Journal of the North American Benthological Society, 2007
BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas... more BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas and information between basic and applied researchers in benthic science. Articles in this series will focus on topical research areas and linkages between basic and applied aspects of research, monitoring, policy, and education. Readers with ideas for topics should contact Associate Editors Nick Aumen and Ashley Moerke.
Electrofishing Effort Required to Estimate Biotic Condition in Southern Idaho Rivers
Http Dx Doi Org 10 1577 M06 115 1, Jan 8, 2011
ABSTRACT
Environmental Monitoring and Assessment
We analyzed data from 1138 wetland sites across the conterminous United States (US) as part of th... more We analyzed data from 1138 wetland sites across the conterminous United States (US) as part of the 2011 National Wetland Condition Assessment (NWCA) to investigate the response of indicators of wetland quality to indicators of human disturbance at regional and continental scales. The strength and nature of these relationships in wetlands have rarely been examined over large regions, due to the paucity of large-scale datasets. Wetland response indicators were a multimetric index of vegetation condition (VMMI), percent relative cover of alien plant species, soil lead and phosphorus, and water column total nitrogen and total phosphorus. Sitelevel disturbance indices were generated from field observations of disturbance types within a circular 140-m radius area around the sample point. Summary indices were calculated representing disturbances for ditching, damming, filling/erosion, hardening, vegetation replacement, and vegetation removal. Landscape-level disturbance associated with agricultural and urban land cover, roads, and human population were based on GIS data layers quantified in 200, 500, and 1000-m circular buffers around each sample point. Among these three buffer sizes, the landscape disturbance indicators were highly correlated and had similar relationships with the response indictors. Consequently, only the 1000-m buffer data were used for subsequent analyses. Disturbance-response models built using only landscape-or only site-level disturbance variables generally explained a small portion of the variance in the response variables (R 2 < 0.2), whereas models using both types of disturbance data were better at predicting wetland responses. The VMMI was the response variable with the strongest relationship to the disturbances assessed in the NWCA (national model R 2 = 0.251). National multiple regression models for the soil and water chemistry
Environmental Monitoring and Assessment
In 2011, the U.S. Environmental Protection Agency conducted the National Wetland Condition Assess... more In 2011, the U.S. Environmental Protection Agency conducted the National Wetland Condition Assessment (NWCA) as part of the National Aquatic Resource Survey (NARS) program to determine the condition of wetlands across the 48 contiguous states of the United States (US). Sites were selected using a generalized random tessellated stratified (GRTS) probability design. We quantified the types, extent, and magnitude of human activities as indicators of potential stress on a sample of 1138 wetland sites representing a target population of 251,546 km 2 of wetlands in the US. We used field observations of the presence and proximity of more than 50 predetermined types of human activity to define two types of indices that quantify human influences on wetlands. We grouped these
Environmental Monitoring and Assessment
stressors were associated with poor vegetation condition in one or another of the subpopulations.... more stressors were associated with poor vegetation condition in one or another of the subpopulations. Overall, hardening had the highest attributable and relative risks in the most different subpopulations. Attributable risks above 25% were observed for vegetation removal in the Coastal Plain, hardening and ditching in the West, and hardening in Estuarine Woody wetlands. Relative risks above 3 were noted for heavy metals and soil phosphorus in the Interior Plains, and vegetation removal, vegetation replacement, and damming in Estuarine Woody wetlands. Relative and attributable risk were added to the data analyses tools used in the NWCA to improve the ability of survey results to assist managers and policy makers in setting priorities based on conditions observed on the ground. These analyses provide useful information to both individual site managers and regional-national policy makers.
Environmental Monitoring and Assessment
One of the biggest challenges when conducting a continental-scale assessment of wetlands is setti... more One of the biggest challenges when conducting a continental-scale assessment of wetlands is setting appropriate expectations for the assessed sites. The challenge occurs for two reasons: (1) tremendous natural environmental heterogeneity exists within a continental landscape and (2) reference sites vary in quality both across and within major regions of the continent. We describe the process used to set reference expectations and define a disturbance gradient for the United States (US) Environmental Protection Agency's National Wetland Condition Assessment (NWCA). The NWCA employed a probability design and sampled 1138 wetland sites across the conterminous US to make an unbiased assessment of wetland condition. NWCA vegetation data were used to define 10 reporting groups based on ecoregion and wetland type that reduced the naturally occurring variation in wetland vegetation associated with continent-wide differences in biogeography. These reporting groups were used as a basis for defining quantitative criteria for least disturbed and most disturbed conditions and developing indices and thresholds for categories of ecological condition and disturbance. The NWCA vegetation assessment was based on a reference site approach, in which the least disturbed reference sites were used to establish benchmarks for assessing the condition of vegetation at other sites. Reference sites for each reporting group were identified by filtering NWCA sample data for disturbance using a series of abiotic variables. Ultimately, 277 least disturbed sites were used to set reference expectations for the NWCA. The NWCA provided a unique opportunity to improve our conceptual and technical understanding of how to best apply a reference condition approach to assessing wetlands across the US. These results will enhance the technical quality of future national assessments.
An improved macroinvertebrate multimetric index for the assessment of wadeable streams in the neotropical savanna
Ecological Indicators
A B S T R A C T Multimetric indices (MMIs) have been successfully used to assess ecological condi... more A B S T R A C T Multimetric indices (MMIs) have been successfully used to assess ecological conditions in freshwater ecosystems worldwide, and provide an important management tool especially in countries where biological indicators are fostered by environmental regulations. Nonetheless, for the neotropics, the few published papers are limited to small local scales and lack standardized sampling protocols. To fill the gaps left by previous studies, we propose a stream MMI that reflects anthropogenic impacts by using macroinvertebrate assemblage metrics from a data set of 190 sites collected from four hydrologic units in the Paraná and São Francisco River Basins, southeastern Brazil. Sites were selected through use of a probabilistic survey design allowing us to infer ecological condition to the total of 9432 kilometers of wadeable streams in the target population in the four hydrologic units. We used a filtering process to determine the least-and most-disturbed sites based on their water quality, physical habitat structure, and land use. To develop the MMI, we followed a stepwise procedure to screen our initial set of biological metrics for influence of natural variation, responsiveness and discriminance to disturbances, sampling variability, and redundancy. The final MMI is the sum of 7 scaled assemblage metrics describing different aspects of macroinvertebrate assemblage characteristics: Ephemeroptera richness, % Gastropoda individuals, Shannon-Wiener diversity index, % sensitive taxa richness, % scraper individuals, temporarily attached taxa richness, and gill respiration taxa richness. The MMI clearly distinguished the least-disturbed sites from the most-disturbed sites and showed a significant negative response to anthropogenic stressors. Of the total length of wadeable streams in the study area, 38%, 35%, and 27% were classified by the MMI as being in good, fair, and poor condition, respectively. By reducing the subjectivity of site selection, rigorously selecting the set of reference sites, and following a standardized metric screening method, we developed a robust MMI to assess and monitor ecological condition in neotropical savanna streams. This improved MMI provides an effective ecological tool to guide decision makers and managers in developing and implementing improved, cost-effective environmental policies, regulations, and monitoring of those systems.
Knowledge and Management of Aquatic Ecosystems
taxons indicateurs, traits de vie sont distingués par la localisation est-ouest, et par des facte... more taxons indicateurs, traits de vie sont distingués par la localisation est-ouest, et par des facteurs qui distinguent les cours d'eau de montagne, des rivières de basse altitude/plaines. Les groupes de l'est et de l'ouest qui ont les mêmes caractéristiques environnementales ont une composition en taxons définis à un niveau grossier très similaire et des traits de vie convergents. Les ordinations confirment que les schémas de composition faits à un niveau de résolution grossier des taxons et les traits des taxons ne reflètent plus des distinctions géographiques mais sont seulement reliés à des facteurs environnementaux non géographiques. Toutefois, les schémas de composition basés sur des traits, des taxons grossiers, et les macro-invertébrés identifiés au niveau le plus fin possible ont tous été corrélés avec les mêmes gradients environnementaux dominants non géographiques.
A synoptic survey of microbial respiration, organic matter decomposition, and carbon efflux in U.S. streams and rivers
Limnology and Oceanography
We analyzed ecoenzyme activities related to organic matter processing in 1879 streams and rivers ... more We analyzed ecoenzyme activities related to organic matter processing in 1879 streams and rivers across the continental U.S. as part of the USEPA's National Rivers and Streams Assessment. Ecoenzymatic stoichiometry was used to construct models for carbon use efficiency (CUE) and decomposition (). Microbial respiration (R) was estimated from sediment organic carbon stocks, CUE and . The streams and rivers were classified by size (headwaters: 1-order; streams: 2-3 order; small rivers: 4-5 order; big rivers 6-7 order; and great rivers ≥ 8 order) and condition class (least, intermediate and most disturbed), and grouped into nine ecoregions. There were ecoregion, stream size, and condition class effects for CUE, , and R, with R increasing from eastern ecoregions through the plains to the western ecoregions. CUE, , and R decreased with increasing streams size and increased with increasing disturbance. R, CUE, and were correlated with water and sediment chemistry; CUE and were also correlated with stream bed fine sediments; and CUE was further correlated with catchment land cover. R was extrapolated to ecoregional and national scales, and the results suggest that microbial assemblages account for 12% of the total CO outgassing, and nearly 50% of the aquatic metabolism C losses, from U.S. streams and rivers. Cumulative respiratory C losses increased from headwaters to small streams, then decreased with increasing stream size. This U-shaped respiration curve was not evident when streams were viewed by disturbance classes, suggesting that anthropogenic disturbances mask the expected organic matter processing signature of the river continuum.
Benthic microbial respiration in Appalachian Mountain, Piedmont, and Coastal Plains streams of the eastern U.S.A
Freshwater Biology, Jan 20, 2002
ABSTRACT
Bioscience, 2002
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
A null model for the expected macroinvertebrate assemblage in streams
Journal of the North American Benthological Society, Mar 1, 2005
Abstract Predictive models such as River InVertebrate Prediction And Classification System (RIVPA... more Abstract Predictive models such as River InVertebrate Prediction And Classification System (RIVPACS) and AUStralian RIVer Assessment System (AUSRIVAS) model the natural variation across geographic regions in the occurrences of macroinvertebrate taxa in data ...
Regional e Stimates O F a Cid M Ine D Rainage I Mpact on Streams in the M Id-Atlantic and Southeastern U Nited States
Water Air Soil Pollut, 1990
Effect of riparian areas on the ecological condition of small, perennial streams in agricultural landscapes of the Willamette Valley : research plan, June 1997
Hydrobiologia, Feb 29, 2004
We assessed the importance of spatial scales (catchment, stream network, and sample reach) on the... more We assessed the importance of spatial scales (catchment, stream network, and sample reach) on the effects of agricultural land-use on lotic diatom assemblages along a land-use gradient in the agricultural Willamette Valley Ecoregion of Oregon. Periphyton, water chemistry, and physical habitat conditions were characterized for 25 wadeable streams during a dry season (July to September, 1997). Additional water chemistry samples were collected in the following wet season (February 1998) to assess seasonal effects of land-use on stream water chemistry. Percent agricultural land-use in the study catchments ranged from 10% to 89% with an average of 52%. Partial canonical correspondence analysis (CCA) with the first axis constrained by % agricultural land-use showed that % agricultural land-use at 3 spatial scales explained between 3.7%-6.3% of variability in the diatom species dataset. Monte Carlo Permutation tests indicated that the variance explained by % agricultural land-use was only significant at the spatial scale of the stream network with 10-and 30-m band width (p < 0.05, 999 permutations). In addition to the effects of % agricultural land-use, partial CCAs with a forward selection option showed that water chemistry (e.g., SiO 2), reach-scale stream channel dimensions (e.g., width, depth, and slope), reach-scale in-stream habitats (substrates and filamentous algal cover in stream beds), and riparian vegetative buffer were all important with relation to diatom species assemblages. Percent of obligately nitrogen-heterotrophic taxa was the only diatom autecological metric that showed a significant but weak correlation with % agricultural land-use along the stream network (r = 0.50), but not at catchment or sample reach scale. Correlation between % agricultural land-use and water chemistry variables varied among the spatial scales and between seasons. Physical habitat variables (log 10 erodible substrate diameters and stream reach slope) were significantly correlated with % agricultural land-use along the stream network but not at catchment or sample reach scale. Our data suggest that spatial scales are important in assessing effects of land-use on stream conditions but the spatial scale effects may vary between seasons. Direct linkages between agricultural land-use and lotic diatom assemblages were weak during summer base-flow time regardless of the spatial scales. Summer sampling may underestimate the effects of catchment land-use on stream conditions in areas where seasonal patterns are so distinctive as in the Willamette Valley.
Fisheries, May 22, 2012
Patrones en la captura por unidad de esfuerzo de peces nativos y peces piscívoros foráneos en sie... more Patrones en la captura por unidad de esfuerzo de peces nativos y peces piscívoros foráneos en siete ríos del Pacífico Noroeste de los Estados Unidos de Norteamérica RESUMEN: es comúnmente aceptado que las especies no nativas o foráneas constituyen una amenaza para las comunidades biológicas locales; no obstante, resulta complicado separar el efecto que tienen estas especies invasoras frente a otras perturbaciones co-variantes. Se evaluó el efecto de los peces piscívoros foráneos sobre especies nativas en siete ríos del Pacífico Noroeste de los Estados Unidos de Norteamérica, mediante un muestreo al azar espacialmente balanceado en 20 localidades dentro de cada río. Los ríos carecían de drenajes importantes y los existentes, de haber alguno, cumplían con los estándares federales en cuanto a calidad del agua. En cada localidad de muestreo se llevó a cabo una colecta por medios eléctricos (electro-pesca) a una distancia equivalente a 50 veces el ancho del canal de inundación; todos los peces fueron identificados a nivel especie, medidos y devueltos vivos a los ríos (excepto aquellos especímenes destinados a museos). En casi todas las localidades de los siete ríos, se encontró que la captura por unidad de esfuerzo (CPUE) de las especies nativas de peces, varió de manera inversa con respecto a la CPUE de los peces piscívoros foráneos. En los dos ríos que estaban dominados mayormente por especies piscívoras, se colectaron especies nativas sólo en el 20-25% de las localidades. Se concluye que, al menos durante los periodos de flujo reducido en el verano, los peces piscívoros foráneos se relacionan con reducciones poblacionales de las especies nativas y constituyen una amenaza potencial a la persistencia de las especies locales.mentos relacionados a la liberación y los derechos de los animales, pueden tener consecuencias muy importantes para las pesquerías recreativas.
Using δ15N of Chironomidae to help assess lake condition and possible stressors in EPA’s National Lakes Assessment
ABSTRACT Background/Question/Methods As interest in continental-scale ecology increases to addres... more ABSTRACT Background/Question/Methods As interest in continental-scale ecology increases to address large-scale ecological problems, ecologists need indicators of complex processes that can be collected quickly at many sites across large areas. We are exploring the utility of stable isotopes from basal food chain organisms in providing information about nitrogen sources and processing at large scales within EPA’s water quality monitoring program. EPA has implemented the National Aquatic Resource Surveys, which use a probabilistic survey design to monitor 1000-2000 sites across the nation per water body type (Lake, River/Stream, Estuary, Wetland). While EPA measures many parameters during the one-day site visits, data on complex processes such as denitrification cannot be measured with such limited visit times. We are exploring the potential for δ15N measured in a family of insects, Chironomidae, which occupies several functional feeding groups in aquatic ecosystems to help classify lakes based on likely sources of or processes that affect nitrogen (N). In 2007, EPA conducted the National Lakes Assessment (NLA) on 1000 lakes, collecting composite benthic invertebrate samples from the littoral zone at 10 locations around each lake shoreline. After samples were counted and identified for biodiversity assessments, chironomids were separated, and then analyzed for δ15N. Results/Conclusions Chironomid δ15N values varied from -2 to 20 ‰ with a mean of 5.7 ‰ and were significantly higher in lakes with high nutrient concentrations. Since δ15N values can vary from both changes in N source (e.g. fertilizer vs. manure) and from N processing such as denitrification, we cannot determine a unique cause of δ15N enrichment. Instead, we used a decision tree approach to categorize lakes for likely N sources and whether denitrification is an important process in watershed N dynamics. Lakes with relatively high fertilizer loading (>10 kg/ha/yr) in the watershed generally had higher chironomid δ15N values suggesting higher nitrogen processing. We found that lakes with atmospheric nitrogen as their dominant loading source had low chironomid δ15N values resembling the low δ15N value of atmospheric deposition. For lakes with sewage or manure as the dominant N source in the watershed, chironomid δ15N values did not vary with watershed loading levels, and with a mean of 5.7 ‰, they did not reflect these relatively enriched δ15N sources. This decision tree approach in conjunction with other NLA data, chironomid δ15N values are promising to be highly useful indicators of denitrification and attributing N sources in national water quality monitoring efforts.
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An important issue surrounding assessment of riverine fish assemblages is the minimum amount of s... more An important issue surrounding assessment of riverine fish assemblages is the minimum amount of sampling distance needed to adequately determine biotic condition. Determining adequate sampling distance is important because sampling distance affects estimates of fish assemblage condition at both local and regional scales, and oversampling is costly. We examined the sampling distance question by sampling 45 raftable Oregon river reaches for an entire day and then assessing the minimum distance needed to obtain index of biotic integrity (IBI) scores in those reaches that varied by less than 10% from the 1-d samples. An electrofishing raft was used to collect fish, and physical and chemical habitats were sampled to aid in reach description. We found that a sampling distance equal to 50 times the mean wetted channel width, or a catch of more than 120 individuals, produced IBI scores that met our criteria.
Theory Can Help Structure Regression Models for Projecting Stream Conditions Under Alternative Land Use Scenarios
ABSTRACT
Regional Variation in Landscape Controls on the Width of Wadeable Streams Across the Conterminous United States
Agu Fall Meeting Abstracts, Dec 1, 2007
We examine regional variations in landscape controls on the width of wadeable streams across the ... more We examine regional variations in landscape controls on the width of wadeable streams across the conterminous United States using a unique dataset from the U.S. Environmental Protection Agency&amp;amp;amp;amp;#39;s (USEPA) Wadeable Streams Assessment (WSA). The WSA dataset includes a probability sample of over 1,300 randomly selected stream reaches (drawn from the 1:100,000 scale USGS digitized stream network) and over 500 hand-
Journal of the North American Benthological Society, 2007
BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas... more BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas and information between basic and applied researchers in benthic science. Articles in this series will focus on topical research areas and linkages between basic and applied aspects of research, monitoring, policy, and education. Readers with ideas for topics should contact Associate Editors Nick Aumen and Ashley Moerke.
Electrofishing Effort Required to Estimate Biotic Condition in Southern Idaho Rivers
Http Dx Doi Org 10 1577 M06 115 1, Jan 8, 2011
ABSTRACT