preserve, protect and enhance the living resources of the state. Working in partnership with the ... more preserve, protect and enhance the living resources of the state. Working in partnership with the citizens of Maryland, this worthwhile goal will become a reality. This publication provides information that will increase your understanding of how DNR strives to reach that goal through its many diverse programs.
This project is to develop tools that will enable the estimation of false positive and false nega... more This project is to develop tools that will enable the estimation of false positive and false negative error rates for the procedure in place for assessing the numerical chlorophyll criteria in the tidal James River. The key tool is a computer simulation that creates chlorophyll data with spatial and temporal patterns that are typical of observed chlorophyll in the James River. This simulation makes it possible to create data on a dense spatial and temporal grid that covers an entire river segment for a three year assessment period. The state of this simulated data is known to be compliant or non-compliant with the numerical criteria. To test for an assessment error, a subset of data are sampled from the simulation with the same spatial and temporal frequency as ship-board sampling of the James River. The full assessment procedure is applied to this sub-sample of simulated data and the result of the assessment is compared to the known state of the simulation. If the assessment finds ...
Archives of Environmental Contamination and Toxicology
This study compared four different statistical methods, involving six estimation procedures, for ... more This study compared four different statistical methods, involving six estimation procedures, for addressing censored left data in measuring temporal trends of eight different pyrethroids measured in sediment from a 10-year data set in a residential California stream (Pleasant Grove Creek). The statistical methods used were: the Kaplan–Meier (km) method; the robust regression on order statistics (ros using normal and log normal distributions rosln); the maximum likelihood estimation (mlen using normal and log normal distributions mleln); and a substitution method (sub) using ½ the detection limit. For five of the eight pyrethroids (bifenthrin, cyfluthrin, cypermethrin, lambda-cyhalothrin, and permethrin), the six statistical methods generally agree, with one exception, that the data set exhibit significant declining trends. In the case of bifenthrin, the slight disagreement among statistical methods only occurred for the mleln estimate that did not show a significant declining trend, whereas the other five methods did. For deltamethrin, esfenvalerate, and fenpropathrin, all six statistical methods were in agreement showing no significant trends. Possible reasons for declining sediment concentrations of pyrethroids in Pleasant Grove Creek are urban label changes effective in 2012–2015 that reduced residential use, variable annual rainfall, and more responsible homeowner use based on outreach/education programs.
Estuarine-coastal ecosystems are rich areas of the global ocean with elevated rates of organic ma... more Estuarine-coastal ecosystems are rich areas of the global ocean with elevated rates of organic matter production supporting major fisheries. Net and gross primary production (NPP, GPP) are essential properties of these ecosystems, characterized by high spatial, seasonal, and inter-annual variability associated with climatic effects on hydrology. Over 20 years ago, Nixon defined the trophic classification of marine ecosystems based on annual phytoplankton primary production (APPP), with categories ranging from “oligotrophic” to “hypertrophic”. Source data consisting of shipboard measurements of NPP and GPP from 1982 to 2004 for Chesapeake Bay in the mid-Atlantic region of the United States supported estimates of APPP from 300 to 500 g C m−2 yr−1, corresponding to “eutrophic” to “hypertrophic” categories. Here, we developed generalized additive models (GAM) to interpolate the limited spatio-temporal resolution of source data. Principal goals were: (1) to develop predictive models of N...
Coincident climatic and human effects strongly influence water-quality properties in estuarine-co... more Coincident climatic and human effects strongly influence water-quality properties in estuarine-coastal ecosystems around the world. time-series data for a number of ecosystems reveal high spatio-temporal variability superimposed on secular trends traceable to nutrient over-enrichment. In this paper, we present new analyses of long-term data for Chesapeake Bay directed at several goals: (1) to distinguish trends from spatio-temporal variability imposed by climatic effects; (2) to assess long-term trends of water-quality properties reflecting degradation and recovery; (3) to propose numerical water-quality criteria as targets for restoration; (4) to assess progress toward attainment of these targets. The bay has experienced multiple impairments associated with nutrient over-enrichment since World War II, e.g., low dissolved oxygen (DO), decreased water clarity, and harmful algal blooms (HAB). Anthropogenic eutrophication has been expressed as increased chlorophyll-a (chl-a) driven by accelerated nutrient loading from 1945 to 1980. Management intervention led to decreased loading thereafter, but deleterious symptoms of excess nutrients persist. Climatic effects exemplified by irregular "dry" and "wet" periods in the last 30+ years largely explain high inter-annual variability of water-quality properties, requiring adjustments to resolve long-term trends. Here, we extend these analyses at a finer temporal scale to six decades of chl-a, secchi depth, and nitrite plus nitrate (No 2 + No 3) data to support trend analyses and the development of numerical water-quality criteria. the proposed criteria build on a conceptual model emphasizing the need to distinguish climatic and human effects in gauging progress to reverse eutrophication in estuarine-coastal ecosystems. Significant changes in estuarine-coastal ecosystems around the world can be traced to climatic and anthropogenic effects 1-4. These changes are manifested as secular trends of water-quality properties driven by human behavior against a backdrop of spatio-temporal variability associated primarily with regional climate fluctuations 5. Long-term data for such ecosystems were limited prior to the 1960s 6 compared to more extensive records for marine and terrestrial ecosystems that supported development of basic ecological concepts 7. Recent analyses of multi-decadal time series have proven effective to identify secular changes for a diverse set of estuarine-coastal ecosystems, including Narragansett Bay in Rhode Island (USA) 8 , Chesapeake Bay in the mid-Atlantic (USA) 9 , the Neuse River estuary in North Carolina (USA) 10 , Tampa Bay in Florida (USA) 11 , the San Francisco Bay estuary in California (USA) 12 , the Baltic Sea in northern Europe 13 , and the northern Adriatic Sea in southern Europe 14. These studies and others supported a global synthesis for ecosystems at the land-sea margin, focusing on long-term trends and major drivers of spatio-temporal variability 5. Progress to define changes in estuarine-coastal ecosystems has benefited from systematic monitoring of water-quality properties, stimulated by efforts to reverse environmental degradation. Several properties are
Nutrient-reduction efforts have been undertaken in recent decades to mitigate the impacts of eutr... more Nutrient-reduction efforts have been undertaken in recent decades to mitigate the impacts of eutrophication in coastal and estuarine systems worldwide. To track progress in response to one of these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United States. Model development included selecting a GAM structure to describe nonlinear seasonally-varying changes over time, incorporating hydrologic variability via either river flow or salinity, and using interventions to model method or laboratory changes suspected to impact data. This approach, transferable to other systems, allows for evaluation of water quality data in a statistically rigorous way, while being suitable for application to many sites and variables. This enables consistent generation of annual updates, while providing a tool for developing insights to a range of management-and researchfocused questions.
In July 1981, the Academy of Natural Sciences of Philadelphia undertook a study to examine the nu... more In July 1981, the Academy of Natural Sciences of Philadelphia undertook a study to examine the numbers of finfish and blue crabs (Callinectes sapidus) entrained through the auxiliary cooling pumps at the Chalk Point Steam Electric Station (SES) operated by the Potomac Electric Power Company. Samples were collected by positioning a net attached to a hinged steel frame directly in
Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our... more Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes cau...
Provisional physical habitat indices were developed and validated for Maryland Coastal and Non-Co... more Provisional physical habitat indices were developed and validated for Maryland Coastal and Non-Coastal Plain streams using variables (commonly called metrics) that best discriminated reference and degraded conditions based on biological, chemical and land use data from the 1994-97 Maryland Biological Stream Survey (MBSS). These habitat indices contained variables that described structural, hydrological, vegetative and aesthetic components of stream habitat. Variables with the best discriminatory power for Coastal Plain streams were: instream habitat, velocity/depth diversity, pool/glide/eddy quality, embeddedness, maximum depth and aesthetic rating. Physical habitat variables with the best discriminatory power for Non-Coastal Plain sites were: instream habitat, velocity/depth diversity, riffle/run quality, embeddedness, number of rootwads and aesthetic rating. The overall classification efficiency for index validation was 76% for both indices pooled over both strata. Scaled physical...
Abstract Fathead minnow ( Pimephales promelas ) 1-d post-hatch larvae, 12-d post-hatch larvae, an... more Abstract Fathead minnow ( Pimephales promelas ) 1-d post-hatch larvae, 12-d post-hatch larvae, and 4-wk post-hatch juveniles were exposed to combinations of acid and inorganic aluminum (Al) for 96 h in the laboratory. Life stages were exposed, under flow-through conditions, to four nominal pH levels: 4.5, 5.5, 6.5, 7.5 (control) and five nominal Al concentrations: 0 (control), 50, 100, 200, 400 μg/l in fresh water with a total hardness of 20–24 mg/l as CaCO 3 . Theoretical speciation of the measured total dissolved monomeric Al was performed in order to estimate the toxic forms of Al. The ranking of life stage sensitivities to acid alone was 1-d larvae, most sensitive, followed by 12-d larvae and juveniles. At pH 4.5, all three stages exhibited 100% mortality in all Al treatments and controls. At pH 5.5, 90–100% mortality occurred in all but the 50 μg/l Al treatment and the no Al control. At that pH, hydroxoid species of Al were the predominate forms of the total dissolved monomeric aluminum. At pH 6.5 and 7.5, Al was not toxic to the 1-d larvae and juveniles, but the mortality of 12-d larvae exposed to Al (predominately hydroxy species) ranged from 18 to 68% with no clear dose response.
North American Journal of Fisheries Management, 2010
Abstract Impingement abundance monitoring was conducted at 15 Ohio River power plants as part of ... more Abstract Impingement abundance monitoring was conducted at 15 Ohio River power plants as part of the Ohio River Ecological Research Program. Impingement rates were compared with environmental, power plant design, and operational factors that varied within and among the power plants, including water temperature, river flow and stage, change in flow and stage during the sampling events, volume of cooling water pumped, design pumping capacity, approach velocity, location of the intakes along the river, intake type, and intake configuration. The study demonstrated similarities in species composition, size distributions, and seasonal patterns over nearly 1,400 river kilometers of the Ohio River, results that were consistent with studies conducted nearly 30 years earlier. Dramatic annual differences in impingement rates during the 2-year study indicated that impingement is largely a function of the recruitment levels of juvenile gizzard shad Dorosoma cepedianum, threadfin shad D. petenense, and freshwater drum ...
North American Journal of Fisheries Management, 2014
AbstractTraveling water screens (TWSs) modified for fish protection can be used at power plant co... more AbstractTraveling water screens (TWSs) modified for fish protection can be used at power plant cooling water intakes to reduce the injury to and mortality of impinged fish. Existing biological efficacy data show that postimpingement survival is highly variable by species and has improved over time as screen designs have incorporated more fish-friendly features. Data with the improved screen designs were largely absent for many freshwater species prior to this evaluation. The mortality, injury, and scale loss rates of 10 species of freshwater fish impinged and recovered with a modified Ristroph-style TWS were evaluated in a laboratory flume. Fish were impinged at a 0.3-, 0.6-, or 0.9-m/s approach velocity. Over 13,000 fish were tested in more than 100 replicates during the study. Mortality rates did not exceed 5% for any species and velocity tested. Despite a general trend toward increasing mortality at higher velocities, velocity was only a significant factor in the mortality of Bluegills Lepomis macrochi...
An analysis of historical and recent data on chlorophyll a for Chesapeake Bay reveals that a sign... more An analysis of historical and recent data on chlorophyll a for Chesapeake Bay reveals that a significant increase of phytoplankton biomass has occurred during the last 40 to 50 yr. Concentrations of chlorophyll a in the surface mixing layer have increased 5-to 10-fold in the seaward regions of the estuary and 1.5-to 2-fold elsewhere, paralleling published estimates of increased loading of N and P to the estuary since World War 11. The characteristic hlgh vanability of freshwater flow that occurs on seasonal to interannual time scales, however, drives fluctuations of chlorophyll a that are superimposed on this apparent upward trend, potentially obscuring the effects of overenrichment on chlorophyll a concentrations in nutrient-limited regions of the Bay To resolve a time trend of chlorophyll from this variability, we developed regional models of mean, monthly chlorophyll a using autoregressive moving average (ARMA) procedures. The models were developed with water quality data from monitoring cruises of the Chesapeake Bay Program spanning 1984 to 1992. The approach was to: (1) determine the relationship of prominent variables, including freshwater flow, salinity, temperature, region, and time of year, to chlorophyll a for the 'modern' Bay; (2) predict chlorophyll a for the 'historical' Bay based on these models and actual, observed variables for periods from 1950 to 1984 for which chlorophyll a data were available; (3) compare chlorophyll a predicted from modern relationships, to those observed in the past, using the residuals to identify deviations below or above expected concentrations that would suggest a n effect o n chlorophyll a unrelated to flow variability. The results show that: (1) observed and predicted chlorophyll a concentrations matched reasonably well for the years that were used to develop the models, with some exceptions when the models failed to capture extremely high concentrations of chlorophyll a during blooms; (2) chlorophyll a concentrations in the 1950% 1960s and 1970s were predominantly lower than predicted by the models, particularly in the mesohaline and polyhaline regions of the estuary that are most susceptible to nutrient limitation; (3) chlorophyll a concentrations were lower in the 1960s than in the 1970s probably as the result of low flow and a concomitant reduction of nutrient loading in the 'dry' 1960s as compared to the 'wet' 1970s; (4) interannual variability was high for both observed and predicted chlorophyll a concentrations in the 1970% and this variability was most strongly expressed in the mesohaline to polyhaline Bay, reflecting the spatial and temporal heterogeneity of phytoplankton that prevailed in that period. These findings support the hypothesis that a significant increase of chlorophyll a has occurred in the lower Bay that cannot be accounted for by variability of freshwater flow and attendant properties.
A sample of 561 persons judged the age and attractiveness of the models in 50 cigarette ads. Seve... more A sample of 561 persons judged the age and attractiveness of the models in 50 cigarette ads. Seventeen percent of the models were perceived, on average, to be significantly younger than 25 years of age, an apparent violation of the tobacco industry's voluntary advertising code. Cigarette ads with young persons were found to appear more often in magazines with younger audiences and for menthol brands. Regardless of viewer age, younger models were judged as more attractive than older models. S INCE the 1950s, cigarette marketers have created distinctive brand images, often by relating attractive lifestyles to cigarette brands. However, critics of the lifestyle strategies maintain that adolescents identify with the "images of independence, strength, maturity and adventurous behavior portrayed in many cigarette advertisements" (McCarthy 1986). They have argued that such images encourage children or young adults to initiate tobacco habits. Because those vulnerable consumers are not in a position to make mature, rational judgments about smoking, claim the critics, bans or restrictions on companies' promo
Choosing the best 316(b) mitigation option is a daunting task. Decision analysis (DA) provides an... more Choosing the best 316(b) mitigation option is a daunting task. Decision analysis (DA) provides an objective framework that can be used to choose among several mitigation strategies where there are multiple objectives and numerous uncertainties. This paper has two objectives: ...
... CHRISTOPHER J. VICTORIA, BONNIE S. WILKERSON, RONALD J. KLAUDA, AND ELGIN S. PERRY ... Benfie... more ... CHRISTOPHER J. VICTORIA, BONNIE S. WILKERSON, RONALD J. KLAUDA, AND ELGIN S. PERRY ... Benfield, Maryland (in mid-March); from Zekiah Swamp Run near Allens Fresh, Mary-land (in late March); and from Black Moshan-non Lake near Julian, Pennsylvania (in mid ...
preserve, protect and enhance the living resources of the state. Working in partnership with the ... more preserve, protect and enhance the living resources of the state. Working in partnership with the citizens of Maryland, this worthwhile goal will become a reality. This publication provides information that will increase your understanding of how DNR strives to reach that goal through its many diverse programs.
This project is to develop tools that will enable the estimation of false positive and false nega... more This project is to develop tools that will enable the estimation of false positive and false negative error rates for the procedure in place for assessing the numerical chlorophyll criteria in the tidal James River. The key tool is a computer simulation that creates chlorophyll data with spatial and temporal patterns that are typical of observed chlorophyll in the James River. This simulation makes it possible to create data on a dense spatial and temporal grid that covers an entire river segment for a three year assessment period. The state of this simulated data is known to be compliant or non-compliant with the numerical criteria. To test for an assessment error, a subset of data are sampled from the simulation with the same spatial and temporal frequency as ship-board sampling of the James River. The full assessment procedure is applied to this sub-sample of simulated data and the result of the assessment is compared to the known state of the simulation. If the assessment finds ...
Archives of Environmental Contamination and Toxicology
This study compared four different statistical methods, involving six estimation procedures, for ... more This study compared four different statistical methods, involving six estimation procedures, for addressing censored left data in measuring temporal trends of eight different pyrethroids measured in sediment from a 10-year data set in a residential California stream (Pleasant Grove Creek). The statistical methods used were: the Kaplan–Meier (km) method; the robust regression on order statistics (ros using normal and log normal distributions rosln); the maximum likelihood estimation (mlen using normal and log normal distributions mleln); and a substitution method (sub) using ½ the detection limit. For five of the eight pyrethroids (bifenthrin, cyfluthrin, cypermethrin, lambda-cyhalothrin, and permethrin), the six statistical methods generally agree, with one exception, that the data set exhibit significant declining trends. In the case of bifenthrin, the slight disagreement among statistical methods only occurred for the mleln estimate that did not show a significant declining trend, whereas the other five methods did. For deltamethrin, esfenvalerate, and fenpropathrin, all six statistical methods were in agreement showing no significant trends. Possible reasons for declining sediment concentrations of pyrethroids in Pleasant Grove Creek are urban label changes effective in 2012–2015 that reduced residential use, variable annual rainfall, and more responsible homeowner use based on outreach/education programs.
Estuarine-coastal ecosystems are rich areas of the global ocean with elevated rates of organic ma... more Estuarine-coastal ecosystems are rich areas of the global ocean with elevated rates of organic matter production supporting major fisheries. Net and gross primary production (NPP, GPP) are essential properties of these ecosystems, characterized by high spatial, seasonal, and inter-annual variability associated with climatic effects on hydrology. Over 20 years ago, Nixon defined the trophic classification of marine ecosystems based on annual phytoplankton primary production (APPP), with categories ranging from “oligotrophic” to “hypertrophic”. Source data consisting of shipboard measurements of NPP and GPP from 1982 to 2004 for Chesapeake Bay in the mid-Atlantic region of the United States supported estimates of APPP from 300 to 500 g C m−2 yr−1, corresponding to “eutrophic” to “hypertrophic” categories. Here, we developed generalized additive models (GAM) to interpolate the limited spatio-temporal resolution of source data. Principal goals were: (1) to develop predictive models of N...
Coincident climatic and human effects strongly influence water-quality properties in estuarine-co... more Coincident climatic and human effects strongly influence water-quality properties in estuarine-coastal ecosystems around the world. time-series data for a number of ecosystems reveal high spatio-temporal variability superimposed on secular trends traceable to nutrient over-enrichment. In this paper, we present new analyses of long-term data for Chesapeake Bay directed at several goals: (1) to distinguish trends from spatio-temporal variability imposed by climatic effects; (2) to assess long-term trends of water-quality properties reflecting degradation and recovery; (3) to propose numerical water-quality criteria as targets for restoration; (4) to assess progress toward attainment of these targets. The bay has experienced multiple impairments associated with nutrient over-enrichment since World War II, e.g., low dissolved oxygen (DO), decreased water clarity, and harmful algal blooms (HAB). Anthropogenic eutrophication has been expressed as increased chlorophyll-a (chl-a) driven by accelerated nutrient loading from 1945 to 1980. Management intervention led to decreased loading thereafter, but deleterious symptoms of excess nutrients persist. Climatic effects exemplified by irregular "dry" and "wet" periods in the last 30+ years largely explain high inter-annual variability of water-quality properties, requiring adjustments to resolve long-term trends. Here, we extend these analyses at a finer temporal scale to six decades of chl-a, secchi depth, and nitrite plus nitrate (No 2 + No 3) data to support trend analyses and the development of numerical water-quality criteria. the proposed criteria build on a conceptual model emphasizing the need to distinguish climatic and human effects in gauging progress to reverse eutrophication in estuarine-coastal ecosystems. Significant changes in estuarine-coastal ecosystems around the world can be traced to climatic and anthropogenic effects 1-4. These changes are manifested as secular trends of water-quality properties driven by human behavior against a backdrop of spatio-temporal variability associated primarily with regional climate fluctuations 5. Long-term data for such ecosystems were limited prior to the 1960s 6 compared to more extensive records for marine and terrestrial ecosystems that supported development of basic ecological concepts 7. Recent analyses of multi-decadal time series have proven effective to identify secular changes for a diverse set of estuarine-coastal ecosystems, including Narragansett Bay in Rhode Island (USA) 8 , Chesapeake Bay in the mid-Atlantic (USA) 9 , the Neuse River estuary in North Carolina (USA) 10 , Tampa Bay in Florida (USA) 11 , the San Francisco Bay estuary in California (USA) 12 , the Baltic Sea in northern Europe 13 , and the northern Adriatic Sea in southern Europe 14. These studies and others supported a global synthesis for ecosystems at the land-sea margin, focusing on long-term trends and major drivers of spatio-temporal variability 5. Progress to define changes in estuarine-coastal ecosystems has benefited from systematic monitoring of water-quality properties, stimulated by efforts to reverse environmental degradation. Several properties are
Nutrient-reduction efforts have been undertaken in recent decades to mitigate the impacts of eutr... more Nutrient-reduction efforts have been undertaken in recent decades to mitigate the impacts of eutrophication in coastal and estuarine systems worldwide. To track progress in response to one of these efforts we use Generalized Additive Models (GAMs) to evaluate a diverse suite of water quality constituents over a 32-year period in the Chesapeake Bay, an estuary on the east coast of the United States. Model development included selecting a GAM structure to describe nonlinear seasonally-varying changes over time, incorporating hydrologic variability via either river flow or salinity, and using interventions to model method or laboratory changes suspected to impact data. This approach, transferable to other systems, allows for evaluation of water quality data in a statistically rigorous way, while being suitable for application to many sites and variables. This enables consistent generation of annual updates, while providing a tool for developing insights to a range of management-and researchfocused questions.
In July 1981, the Academy of Natural Sciences of Philadelphia undertook a study to examine the nu... more In July 1981, the Academy of Natural Sciences of Philadelphia undertook a study to examine the numbers of finfish and blue crabs (Callinectes sapidus) entrained through the auxiliary cooling pumps at the Chalk Point Steam Electric Station (SES) operated by the Potomac Electric Power Company. Samples were collected by positioning a net attached to a hinged steel frame directly in
Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our... more Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes cau...
Provisional physical habitat indices were developed and validated for Maryland Coastal and Non-Co... more Provisional physical habitat indices were developed and validated for Maryland Coastal and Non-Coastal Plain streams using variables (commonly called metrics) that best discriminated reference and degraded conditions based on biological, chemical and land use data from the 1994-97 Maryland Biological Stream Survey (MBSS). These habitat indices contained variables that described structural, hydrological, vegetative and aesthetic components of stream habitat. Variables with the best discriminatory power for Coastal Plain streams were: instream habitat, velocity/depth diversity, pool/glide/eddy quality, embeddedness, maximum depth and aesthetic rating. Physical habitat variables with the best discriminatory power for Non-Coastal Plain sites were: instream habitat, velocity/depth diversity, riffle/run quality, embeddedness, number of rootwads and aesthetic rating. The overall classification efficiency for index validation was 76% for both indices pooled over both strata. Scaled physical...
Abstract Fathead minnow ( Pimephales promelas ) 1-d post-hatch larvae, 12-d post-hatch larvae, an... more Abstract Fathead minnow ( Pimephales promelas ) 1-d post-hatch larvae, 12-d post-hatch larvae, and 4-wk post-hatch juveniles were exposed to combinations of acid and inorganic aluminum (Al) for 96 h in the laboratory. Life stages were exposed, under flow-through conditions, to four nominal pH levels: 4.5, 5.5, 6.5, 7.5 (control) and five nominal Al concentrations: 0 (control), 50, 100, 200, 400 μg/l in fresh water with a total hardness of 20–24 mg/l as CaCO 3 . Theoretical speciation of the measured total dissolved monomeric Al was performed in order to estimate the toxic forms of Al. The ranking of life stage sensitivities to acid alone was 1-d larvae, most sensitive, followed by 12-d larvae and juveniles. At pH 4.5, all three stages exhibited 100% mortality in all Al treatments and controls. At pH 5.5, 90–100% mortality occurred in all but the 50 μg/l Al treatment and the no Al control. At that pH, hydroxoid species of Al were the predominate forms of the total dissolved monomeric aluminum. At pH 6.5 and 7.5, Al was not toxic to the 1-d larvae and juveniles, but the mortality of 12-d larvae exposed to Al (predominately hydroxy species) ranged from 18 to 68% with no clear dose response.
North American Journal of Fisheries Management, 2010
Abstract Impingement abundance monitoring was conducted at 15 Ohio River power plants as part of ... more Abstract Impingement abundance monitoring was conducted at 15 Ohio River power plants as part of the Ohio River Ecological Research Program. Impingement rates were compared with environmental, power plant design, and operational factors that varied within and among the power plants, including water temperature, river flow and stage, change in flow and stage during the sampling events, volume of cooling water pumped, design pumping capacity, approach velocity, location of the intakes along the river, intake type, and intake configuration. The study demonstrated similarities in species composition, size distributions, and seasonal patterns over nearly 1,400 river kilometers of the Ohio River, results that were consistent with studies conducted nearly 30 years earlier. Dramatic annual differences in impingement rates during the 2-year study indicated that impingement is largely a function of the recruitment levels of juvenile gizzard shad Dorosoma cepedianum, threadfin shad D. petenense, and freshwater drum ...
North American Journal of Fisheries Management, 2014
AbstractTraveling water screens (TWSs) modified for fish protection can be used at power plant co... more AbstractTraveling water screens (TWSs) modified for fish protection can be used at power plant cooling water intakes to reduce the injury to and mortality of impinged fish. Existing biological efficacy data show that postimpingement survival is highly variable by species and has improved over time as screen designs have incorporated more fish-friendly features. Data with the improved screen designs were largely absent for many freshwater species prior to this evaluation. The mortality, injury, and scale loss rates of 10 species of freshwater fish impinged and recovered with a modified Ristroph-style TWS were evaluated in a laboratory flume. Fish were impinged at a 0.3-, 0.6-, or 0.9-m/s approach velocity. Over 13,000 fish were tested in more than 100 replicates during the study. Mortality rates did not exceed 5% for any species and velocity tested. Despite a general trend toward increasing mortality at higher velocities, velocity was only a significant factor in the mortality of Bluegills Lepomis macrochi...
An analysis of historical and recent data on chlorophyll a for Chesapeake Bay reveals that a sign... more An analysis of historical and recent data on chlorophyll a for Chesapeake Bay reveals that a significant increase of phytoplankton biomass has occurred during the last 40 to 50 yr. Concentrations of chlorophyll a in the surface mixing layer have increased 5-to 10-fold in the seaward regions of the estuary and 1.5-to 2-fold elsewhere, paralleling published estimates of increased loading of N and P to the estuary since World War 11. The characteristic hlgh vanability of freshwater flow that occurs on seasonal to interannual time scales, however, drives fluctuations of chlorophyll a that are superimposed on this apparent upward trend, potentially obscuring the effects of overenrichment on chlorophyll a concentrations in nutrient-limited regions of the Bay To resolve a time trend of chlorophyll from this variability, we developed regional models of mean, monthly chlorophyll a using autoregressive moving average (ARMA) procedures. The models were developed with water quality data from monitoring cruises of the Chesapeake Bay Program spanning 1984 to 1992. The approach was to: (1) determine the relationship of prominent variables, including freshwater flow, salinity, temperature, region, and time of year, to chlorophyll a for the 'modern' Bay; (2) predict chlorophyll a for the 'historical' Bay based on these models and actual, observed variables for periods from 1950 to 1984 for which chlorophyll a data were available; (3) compare chlorophyll a predicted from modern relationships, to those observed in the past, using the residuals to identify deviations below or above expected concentrations that would suggest a n effect o n chlorophyll a unrelated to flow variability. The results show that: (1) observed and predicted chlorophyll a concentrations matched reasonably well for the years that were used to develop the models, with some exceptions when the models failed to capture extremely high concentrations of chlorophyll a during blooms; (2) chlorophyll a concentrations in the 1950% 1960s and 1970s were predominantly lower than predicted by the models, particularly in the mesohaline and polyhaline regions of the estuary that are most susceptible to nutrient limitation; (3) chlorophyll a concentrations were lower in the 1960s than in the 1970s probably as the result of low flow and a concomitant reduction of nutrient loading in the 'dry' 1960s as compared to the 'wet' 1970s; (4) interannual variability was high for both observed and predicted chlorophyll a concentrations in the 1970% and this variability was most strongly expressed in the mesohaline to polyhaline Bay, reflecting the spatial and temporal heterogeneity of phytoplankton that prevailed in that period. These findings support the hypothesis that a significant increase of chlorophyll a has occurred in the lower Bay that cannot be accounted for by variability of freshwater flow and attendant properties.
A sample of 561 persons judged the age and attractiveness of the models in 50 cigarette ads. Seve... more A sample of 561 persons judged the age and attractiveness of the models in 50 cigarette ads. Seventeen percent of the models were perceived, on average, to be significantly younger than 25 years of age, an apparent violation of the tobacco industry's voluntary advertising code. Cigarette ads with young persons were found to appear more often in magazines with younger audiences and for menthol brands. Regardless of viewer age, younger models were judged as more attractive than older models. S INCE the 1950s, cigarette marketers have created distinctive brand images, often by relating attractive lifestyles to cigarette brands. However, critics of the lifestyle strategies maintain that adolescents identify with the "images of independence, strength, maturity and adventurous behavior portrayed in many cigarette advertisements" (McCarthy 1986). They have argued that such images encourage children or young adults to initiate tobacco habits. Because those vulnerable consumers are not in a position to make mature, rational judgments about smoking, claim the critics, bans or restrictions on companies' promo
Choosing the best 316(b) mitigation option is a daunting task. Decision analysis (DA) provides an... more Choosing the best 316(b) mitigation option is a daunting task. Decision analysis (DA) provides an objective framework that can be used to choose among several mitigation strategies where there are multiple objectives and numerous uncertainties. This paper has two objectives: ...
... CHRISTOPHER J. VICTORIA, BONNIE S. WILKERSON, RONALD J. KLAUDA, AND ELGIN S. PERRY ... Benfie... more ... CHRISTOPHER J. VICTORIA, BONNIE S. WILKERSON, RONALD J. KLAUDA, AND ELGIN S. PERRY ... Benfield, Maryland (in mid-March); from Zekiah Swamp Run near Allens Fresh, Mary-land (in late March); and from Black Moshan-non Lake near Julian, Pennsylvania (in mid ...
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