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Articles 301 - 330 of 898

Full-Text Articles in Physical Sciences and Mathematics

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson Aug 2016

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …


Assessment Of Streamside Management Zones For Conserving Benthic Macroinvertebrate Communities Following Timber Harvest In Eastern Kentucky Headwater Catchments, Joshua K. Adkins, Christopher D. Barton, Scott Grubbs, Jeffrey W. Stringer, Randall K. Kolka Jun 2016

Assessment Of Streamside Management Zones For Conserving Benthic Macroinvertebrate Communities Following Timber Harvest In Eastern Kentucky Headwater Catchments, Joshua K. Adkins, Christopher D. Barton, Scott Grubbs, Jeffrey W. Stringer, Randall K. Kolka

Forestry and Natural Resources Faculty Publications

Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ) configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP) utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the …


Slides: Data Sharing And River Basin Modelling: From The Colorado To The Nile, Kevin Wheeler Jun 2016

Slides: Data Sharing And River Basin Modelling: From The Colorado To The Nile, Kevin Wheeler

Coping with Water Scarcity in River Basins Worldwide: Lessons Learned from Shared Experiences (Martz Summer Conference, June 9-10)

Presenter: Kevin Wheeler, University of Oxford

29 slides


Slides: Environmental Flows In The Era Of 'River Anthropology', Rebecca Tharme Jun 2016

Slides: Environmental Flows In The Era Of 'River Anthropology', Rebecca Tharme

Coping with Water Scarcity in River Basins Worldwide: Lessons Learned from Shared Experiences (Martz Summer Conference, June 9-10)

Presenter: Rebecca Tharme, Riverfutures Ltd.

18 slides


Slides: Environmental Flow Case Studies: Southern And Eastern Africa, Rebecca Tharme, Kelly Fouchy, Susan Graas, John Conallin, Michael Mcclain, Unesco-Ihe, Felister Mombo, Sokoine University Of Agriculture Jun 2016

Slides: Environmental Flow Case Studies: Southern And Eastern Africa, Rebecca Tharme, Kelly Fouchy, Susan Graas, John Conallin, Michael Mcclain, Unesco-Ihe, Felister Mombo, Sokoine University Of Agriculture

Coping with Water Scarcity in River Basins Worldwide: Lessons Learned from Shared Experiences (Martz Summer Conference, June 9-10)

Presenter: Rebecca Tharme, Riverfutures Ltd.

17 slides


Slides: Policy Framework: Fpwec: First Peoples' Water Engagement Council, Phil Duncan, First Peoples' Water Engagement Council Jun 2016

Slides: Policy Framework: Fpwec: First Peoples' Water Engagement Council, Phil Duncan, First Peoples' Water Engagement Council

Indigenous Water Justice Symposium (June 6)

Presenter: Phil Duncan, Gomeroi Nation, New South Wales Aboriginal Land Council

25 slides


Bella Vista Lakes Project: Fertility Management, J. Thad Scott Jun 2016

Bella Vista Lakes Project: Fertility Management, J. Thad Scott

Arkansas Water Resources Center Technical Reports

No abstract provided.


Water Quality In Selected Small Drinking Water Systems Of Missouri Rural Communities, Bin Hua, Ruipu Mu, Honglan Shi, Enos Inniss, John Yang Jun 2016

Water Quality In Selected Small Drinking Water Systems Of Missouri Rural Communities, Bin Hua, Ruipu Mu, Honglan Shi, Enos Inniss, John Yang

Chemistry Faculty Research & Creative Works

Small drinking water treatment systems (serving < 10,000 population) in rural communities frequently encounter multiple challenges in water quality and federal regulatory compliance, especially the disinfection byproduct (DBP) regulations, due to source water variations, limited resources, and aging infrastructures. Unlike most studies on the DBP control using synthetic water in laboratory settings, this research aimed to identify the major water quality issues confronting small systems in the state of Missouri (MO), the United States of America (USA). Three small systems were selected based on source water and geographic locations. Water samples were collected quarterly from each major treatment process during the period of May 2012 to March 2013 and analyzed to identify the treatment effectiveness and potential water quality issues in each small system. Results of water quality characterization showed that the major water quality issue in the selected small systems was the low efficiency of dissolved organic carbon (DOC) removal, especially the DOC species that are considered as the DBP precursors. Most collected water samples had a higher trihalomethane formation potential (THMFP) than the United States Environmental Protection Agency (USEPA) maximum contaminant limit (MCL) (80 µg/L). Based on the analysis of the treatment efficiency in each system, several strategies for water quality improvement were recommended, and a few of which have been implemented in the small systems, leading to improved drinking water quality and compliance with the USEPA DBP regulations. This study would provide a valuable aid to small system operators and local water authority in context of water quality improvement and the regulatory compliance.


Effects Of Agricultural Restoration Practices On Stream Health In The Shenandoah Valley, Virginia, Erin L. Thady May 2016

Effects Of Agricultural Restoration Practices On Stream Health In The Shenandoah Valley, Virginia, Erin L. Thady

Senior Honors Projects, 2010-2019

The Shenandoah Valley encompasses some of the highest agricultural producing regions in Virginia, many of which are large contributors of nutrients and sediment. The Conservation Reserve Enhancement Program (CREP) assists landowners in the installation of riparian restoration projects in which cattle are fenced out or a riparian buffer is planted. We examined the temporal effects of riparian restoration and the impact of upstream landuse on water quality for eleven farms participating in the CREP program for various times (from 1 to 14 years). We hypothesized that the length of time that the CREP program has been established would have a …


Impacts Of Environmental Quality On The Demographics Of Three Nations, Emily Hummel May 2016

Impacts Of Environmental Quality On The Demographics Of Three Nations, Emily Hummel

Honors Projects

This study will examine how the correlation between air and water quality and the population demographics of India, South Africa, and the United States. India is a country with a growing population, increasing income inequality, and gender roles that reflect its status as a developing nation. South Africa is much smaller in area and the population is beginning to level off, but South Africa’s income inequality is growing much faster than India’s and gender inequality is less of an issue in South Africa. The population of the United States is decreasing and gender roles are fairly equal, despite income inequality …


Patterns And Sources Of Anthropogenic Contaminants In The Otter Creek Watershed, Madison County, Kentucky, Elijah J. Wolfe May 2016

Patterns And Sources Of Anthropogenic Contaminants In The Otter Creek Watershed, Madison County, Kentucky, Elijah J. Wolfe

EKU Faculty and Staff Scholarship

Stream systems are often affected by anthropogenic activities that affect water quality and stream ecosystems. Land use typically determines the type and quantity of anthropogenic contaminants entering natural waters. The Otter Creek watershed (170 km2; Madison County, Kentucky) consists predominantly of pasture and rural housing, with some cropland. The basin also receives runoff from the town of Richmond and a sewage treatment plant operates within the watershed. We measured concentrations of nutrients (phosphate, ammonium, nitrate) and fecal microbes to discover levels of anthropogenic contaminants affecting water quality and to identify contaminant sources.

We sampled 4 times in the …


Evaluation Of Rusle 2 To Estimate Soil Loss From Pastures, Stasha Katrina Balkissoon May 2016

Evaluation Of Rusle 2 To Estimate Soil Loss From Pastures, Stasha Katrina Balkissoon

Graduate Theses and Dissertations

The accurate estimation of soil erosion by the Revised Universal Soil Loss Equation version 2 (RUSLE2) is critical for several conservation assessments, least of which is its use in the Phosphorus Index (PI) to identify and rank the vulnerability of agricultural fields to phosphorus (P) runoff. Earlier versions of RUSLE reported a soil loss overestimation, which were revised to give RUSLE2, where biomass production in different climatic regions was more accurately represented. RUSLE version 2.0, which contains the new vegetative biomass production routine, was evaluated using two performance indices, the Nash Sutcliffe Efficiency Index (NSE) and Index of Agreement (D) …


Temporal Variations Of Citizens’ Demands On Flood Damage Mitigation, Streamflow Quantity And Quality In The Korean Urban Watershed, Change-Yu Hong, Eun-Sung Chung Apr 2016

Temporal Variations Of Citizens’ Demands On Flood Damage Mitigation, Streamflow Quantity And Quality In The Korean Urban Watershed, Change-Yu Hong, Eun-Sung Chung

Urban Studies and Planning Faculty Publications and Presentations

Sustainable watershed management (SWM) can be achieved through recognition and reflection upon the values of citizens. Collaborative governance consisting of citizens is crucial for successful SWM. Collaborative governance definitely requires an active participatory decision-making process that reflects citizens’ preferences. Citizen preference also tends to substantially change with life pattern and life quality. These shifts can be caused by slight variations in both social priorities and personal preferences for SWM. Therefore, collaborative water governance must be frequently renewed in response to citizens’ values through the participatory framework. The An’yang Stream in South Korea is generally regarded as a representative urban stream …


Effect Of Bioenergy Crops And Fast Growing Trees On Hydrology And Water Quality In The Little Vermilion River Watershed, Tian Guo Apr 2016

Effect Of Bioenergy Crops And Fast Growing Trees On Hydrology And Water Quality In The Little Vermilion River Watershed, Tian Guo

Open Access Dissertations

Energy security and sustainability require a suite of biomass crops, including woody species. Short rotation woody crops (SRWCs) such as Populus have great potential as biofuel feedstocks. Quantifying biomass yields of bioenergy crop and hydrologic and water quality responses to growth is important should it be widely planted in the Midwestern U.S. Subsurface tile drainage systems enable the Midwest area to become highly productive agricultural lands, but also create environmental problems like nitrate-N contamination of the water it drains. The Soil and Water Assessment Tool (SWAT) has been used to model watersheds with tile drainage, but the new tile drainage …


Research: South Dakota State University, Spring 2016, Christie Delfanian, Emily Weber Apr 2016

Research: South Dakota State University, Spring 2016, Christie Delfanian, Emily Weber

State of Discovery South Dakota State University's Research Magazine

CONTENTS:

Genome Researcher investigate impact of L1 jumping genes [Page] 2
CRP funds important resource for hunters [Page] 3
Nurse-researchers help health-care facilities develop, improve tobacco-free policies [Page] 3
MS: Exercise scientist improves movement, quality of life for MS patients [Page] 5
Plant scientists defend South Dakota crops against diseases [Plant] 7
Investigating influenza D virus earns doctoral student scholarship [Page] 9
Steel shavings trap phosphorous, protecting water quality [Page] 10


Bacterial Indicators Of Fecal Pollution: Exploring Relationships Between Fecal Coliform And Enterococcus Groups In Central And South Florida Surface Waters, Shelby G. Craig Mar 2016

Bacterial Indicators Of Fecal Pollution: Exploring Relationships Between Fecal Coliform And Enterococcus Groups In Central And South Florida Surface Waters, Shelby G. Craig

HCNSO Student Theses and Dissertations

Ambient and recreational surface waters worldwide experience fecal pollution due to a variety of anthropogenic sources. Fecal waste has been proven, for over a century, to harbor pathogenic microorganisms which subsequently cause a variety of disease and illness in human hosts. The benefits of utilizing fecal indicator bacteria (FIB) as a simple, inexpensive means to detect fitful human pathogens within a variety of water matrices are vast. However, no universal agreement exists in regard to which indicator is best suited for detection of fecal contamination and pathogens in environmental waters, and no single standard for bacterial indicators has been federally …


Patterns And Sources Of Anthropogenic Contaminants In The Otter Creek Watershed, Madison County, Kentucky, Elijah D. Wolfe, Walter S. Borowski, Jacob L. Robin Mar 2016

Patterns And Sources Of Anthropogenic Contaminants In The Otter Creek Watershed, Madison County, Kentucky, Elijah D. Wolfe, Walter S. Borowski, Jacob L. Robin

EKU Faculty and Staff Scholarship

Stream systems are often affected by anthropogenic contaminants that affect water quality and stream ecosystems. Land use determines the type and quantity of contaminants present in natural waters. The Otter Creek watershed (170 km2; Madison County, Kentucky) consists predominantly of pasture and rural housing, with some cropland. The basin also receives runoff from the town of Richmond and a sewage treatment plant operates within the watershed. We measured concentrations of nutrients (phosphate, ammonium, nitrate) and fecal microbes to discover levels of anthropogenic contaminants affecting water quality and to identify contaminant sources.

We sampled 4 times in the summer …


Expansion Of The Manage Database With Forest And Drainage Studies, Daren R. Harmel, Laura E. Christianson, Matthew W. Mcbroom, Douglas R. Smith, Kori D. Higgs Jan 2016

Expansion Of The Manage Database With Forest And Drainage Studies, Daren R. Harmel, Laura E. Christianson, Matthew W. Mcbroom, Douglas R. Smith, Kori D. Higgs

Faculty Publications

The “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was published in 2006 to expand an early 1980s compilation of nutrient export (load) data from cultivated and pasture/range land at the field or farm scale. Then in 2008, MANAGE was updated with 15 additional studies, and nitrogen (N) and phosphorus (P) concentrations in runoff were added. Since then, MANAGE has undergone significant expansion adding N and P water quality along with relevant management and site characteristic data from: (1) 30 runoff studies from forested land uses, (2) 91 drainage water quality studies from drained land, and (3) 12 additional …


Enhancing Watershed Planning In Implementation Of The Colorado Water Plan: An Overview Of Implementation Challenges And Opportunities, Douglas S. Kenney Jan 2016

Enhancing Watershed Planning In Implementation Of The Colorado Water Plan: An Overview Of Implementation Challenges And Opportunities, Douglas S. Kenney

Books, Reports, and Studies

25 pages.

Introduction -- Review of existing efforts -- Summary of interviews -- The salience of funding -- Recommendations -- Attachment A: Summary of reviewed watershed plans.


Great South Bay, Long Island, New York Summer Water Quality Monitoring Program, Cercom, Molloy University, John Tanacredi Ph.D., Sixto E. Portilla Jan 2016

Great South Bay, Long Island, New York Summer Water Quality Monitoring Program, Cercom, Molloy University, John Tanacredi Ph.D., Sixto E. Portilla

CERCOM Reports

In 2016 the Center for Environmental Research and Coastal Oceans Monitoring (CERCOM) visited 9 locations in Great South Bay to monitor for dissolved oxygen (DO), pH, salinity, clarity, depth and temperature. This monitoring program has been conducted for the past 14 years. These parameters are critical in determining long-term water quality conditions in Long Island estuaries. Methodologies for monitoring parameters are provided by the Standard Methods for the Examination of Water and Wastewater 20th Edition (1998). Criteria for determining water quality conditions in marine eco-systems are based on the type of contact (uses) people have with the water system. The …


Non-Point Sources And Point Sources For Nutrient And Fecal Microbe Contamination In A Typical Upland Stream: Tates Creek, Madison County, Kentucky, Walter S. Borowski, Malcolm P. Frisbie Jan 2016

Non-Point Sources And Point Sources For Nutrient And Fecal Microbe Contamination In A Typical Upland Stream: Tates Creek, Madison County, Kentucky, Walter S. Borowski, Malcolm P. Frisbie

EKU Faculty and Staff Scholarship

Tates Creek (Madison County, Kentucky) is characterized by an oversupply of nutrients and fecal microbe contamination. Its watershed is dominated by pastureland and immature woodlands with scattered settlements served by septic systems, whereas, 5% of the watershed drains urban areas of Richmond, Kentucky. Creek waters are eutrophic and commonly display levels of Escherichia coli deemed unfit for human contact by United States Environmental Protection Agency standards. Both point and non-point sources existed for stream contaminants. A secondary sewage treatment plant (STP) discharged effluent into the creek until mid-2011 and was a point source for nitrate and phosphate. Pastureland likely contributes …


A Step In The Right Direction: Streambank Restoration Efforts At The Botanical Garden Of The Ozarks, Dylan S. Milholen, Madison Brown, Steven Thao, Lisa S. Wood Jan 2016

A Step In The Right Direction: Streambank Restoration Efforts At The Botanical Garden Of The Ozarks, Dylan S. Milholen, Madison Brown, Steven Thao, Lisa S. Wood

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

The Botanical Garden of the Ozarks (BGO) is a unique destination in Northwest Arkansas that draws more than 80,000 visitors a year. While the BGO manages low-input practices, run-off from pesticide application and synthetic fertilizers containing phosphorus and nitrogen are of concern to water quality, habitat, and overall ecological interactions of the BGO streambanks and adjacent Hilton Creek, which flows directly into Lake Fayetteville. One way to reduce pollution to waterbodies is through the use of riparian buffers. This project sought to establish a riparian buffer immediately adjacent to a portion of Hilton Creek in an effort to improve ecological …


Assessing Downstream Stormwater Impacts For Urban Watershed Planning, Johanna Meyer Pavlowsky Jan 2016

Assessing Downstream Stormwater Impacts For Urban Watershed Planning, Johanna Meyer Pavlowsky

Masters Theses

"The urbanization of watersheds has caused debilitating effects to downstream aquatic ecosystems in catchments and streams. The implementation of green infrastructure (GI), such as permeable pavements and bioretention facilities, has been shown to alleviate these effects by both reducing runoff and mitigating pollutants; however, the implements are often not designed with a specific goal of water improvement. This study targets understanding a small, impaired urban watershed, and the benefits green infrastructure may have to provide environmental, social, and economic improvement to the watershed.

Portions of Rolla including much of the S&T campus drain into the impaired urban waterbody Frisco Lake, …


Wetlands And Coastal Systems: Protecting And Restoring Valuable Ecosystems, Carmen T. Agouridis, Kyle R. Douglas-Mankin, Anna C. Linhoss, Aaron R. Mittelstet Jan 2016

Wetlands And Coastal Systems: Protecting And Restoring Valuable Ecosystems, Carmen T. Agouridis, Kyle R. Douglas-Mankin, Anna C. Linhoss, Aaron R. Mittelstet

Biosystems and Agricultural Engineering Faculty Publications

Wetlands and coastal systems are unique, highly productive, and often threatened landscapes that provide a host of services to both humans and the environment. This article introduces a five-article Wetlands and Coastal Systems Special Collection that evolved from a featured session at the 2015 ASABE Annual International Meeting in New Orleans, Louisiana. The Collection provides perspectives on tools and techniques for enhancing the protection and restoration of wetlands and coastal systems with emphasis on vegetation, hydrology, water quality, and planning. Topics span the Florida Everglades (two articles) and Virginia floodplain (one article) wetland systems and include remote sensing (one article) …


Predicting The Water Quality Of Shallow Arctic Ponds Using Remote Sensing, Gabriela Tarin Jan 2016

Predicting The Water Quality Of Shallow Arctic Ponds Using Remote Sensing, Gabriela Tarin

Open Access Theses & Dissertations

Barrow, Alaska is in a region dominated by Arctic tundra of which a substantial part is covered by lakes and ponds. Despite their dominance in the landscape, freshwater ecosystems in the Arctic have been insufficiently studied. It is clear that furthering understanding of how Arctic water bodies are responding to warming will depend on the analysis of changes in the concentration of organic and inorganic constituents in the water; however, scientists are faced with the task of sampling many remote sites in a relatively hostile environment. Thus, the exploration and incorporation of remote methods for monitoring changes in water quality. …


Modeled Inflow Validation & Nutrient Loading Estimation In Two Subwatersheds Of The Lower Laguna Madre, Hudson R. Deyoe, Warren Pulich, Nelun Fernando Jan 2016

Modeled Inflow Validation & Nutrient Loading Estimation In Two Subwatersheds Of The Lower Laguna Madre, Hudson R. Deyoe, Warren Pulich, Nelun Fernando

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

University of Texas Rio Grande Valley will characterize nutrient loading rates into the Lower Laguna Madre for subwatersheds by monitoring stream flow and water quality (particularly total nitrogen and phosphorus). This information will be used to evaluate Texas Rainfall-Runoff model performance in estimating ungaged inflows and to establish a relationship between ungaged inflows and nutrient loading regimes to the Lower Laguna Madre. View on Map


Estimating The Water Quality Condition Of River And Lake Water In The Midwestern United States From Its Spectral Characteristics, Jing Tan Dec 2015

Estimating The Water Quality Condition Of River And Lake Water In The Midwestern United States From Its Spectral Characteristics, Jing Tan

Open Access Dissertations

This study focuses on developing/calibrating remote sensing algorithms for water quality retrieval in Midwestern rivers and lakes. In the first part of this study, the spectral measurements collected using a hand-held spectrometer as well as water quality observations for the Wabash River and its tributary the Tippecanoe River in Indiana were used to develop empirical models for the retrieval of chlorophyll (chl) and total suspended solids (TSS). A method for removing sky and sun glint from field spectra for turbid inland waters was developed and tested. Empirical models were then developed using a subset of the field measurements with the …


Understanding The Impact Of Intensive Horticulture Land-Use Practices On Surface Water Quality In Central Kenya, Faith K. Muriithi, Danlin Yu Dec 2015

Understanding The Impact Of Intensive Horticulture Land-Use Practices On Surface Water Quality In Central Kenya, Faith K. Muriithi, Danlin Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Rapid expansion of commercial horticulture production and related activities contribute to declining surface water quality. The study sought to understand the impacts on select rivers in Laikipia and Meru, production hotspots. The specific aims were (1) to identify prevailing surface water quality by examining variations of 14 physico-chemical parameters, and (2) to categorize measured surface water quality parameters into land use types highlighting potential pollutant source processes. Water samples were collected in July and August 2013 along 14 rivers in the study area. The data were analyzed using principal component analysis (PCA) and discriminant analysis (DA). Principal components (PCs) explained …


Swat Model Simulation Of Bioenergy Crop Impacts On Water Quality In Cache River Watershed, Eeshan Kumar Dec 2015

Swat Model Simulation Of Bioenergy Crop Impacts On Water Quality In Cache River Watershed, Eeshan Kumar

Graduate Theses and Dissertations

Energy security through increased biofuel production is one of the components of the Energy Independence and Security Act (EISA) 2007. As per EISA 2007 mandate, appropriate independent research institutes are required to assess concerns to natural biodiversity due to biofuel production and report it to the Congress through the Environment Protection Agency (EPA). Planners, researchers, and agencies concerned with environmental regulations, ideally, would like to have location-specific information about the impacts for developing appropriate management interventions. This study examines long-term impacts on water quality in response to targeted (i.e. marginal lands) production of biofuel crops by setting up two SWAT …


Current Status And Long-Term Trends In Water Quality And Living Resources In The Virginia Tributaries And Chesapeake Bay Mainstem From 1985 Through 2014, Daniel M. Dauer, Todd A. Egerton, John R. Donat, Michael F. Lane, Suzanne C. Doughten, Cindy Johnson, Monika Arora Dec 2015

Current Status And Long-Term Trends In Water Quality And Living Resources In The Virginia Tributaries And Chesapeake Bay Mainstem From 1985 Through 2014, Daniel M. Dauer, Todd A. Egerton, John R. Donat, Michael F. Lane, Suzanne C. Doughten, Cindy Johnson, Monika Arora

Status and Trends for Virginia Chesapeake Bay

The period prior to the implementation of the Chesapeake Bay Monitoring Program was characterized by a marked decline in the water quality of the Chesapeake Bay. The disappearance of submerged aquatic vegetation in certain regions of the Bay, declines in the abundance of some commercially and recreationally important species, increases in the incidence of low dissolved oxygen events, changes in the Bay's food web, and other ecological problems have been related to the deteriorating water quality (e.g. USEPA, 1982,1983;Officer et al.,1984; Orth and Moore, 1984). The results of concerted research efforts in the late 1970s and early 1980s stimulated the …