The Intersection of Science and Management: Improving the Scientific Foundation for Nutrient Criteria Development I
Presiding: J R Stevenson, Michigan State University; C R Bauer, U.S. Environmental Protection Agency Region 5; D Tillman, U.S. Environmental Protection Agency, Office of Research and Development; D Pfeifer, U.S. Environmental Protection Agency Region 5
NB13E-01 INVITED 13:30h
A New Vision for Partnerships between Water Quality Practitioners and the Research Community: Nutrient Criteria Development
State water quality assessments repeatedly cite nutrients as one of the top three causes of use impairment in surface waters. The United States Environmental Protection Agency (USEPA) published recommendations for nutrient water quality criteria in 2001 to assist States and others in addressing this source of surface water impairment. These criteria provide numeric targets for use in interpreting monitoring data, establishing pollution controls, and assessing progress. USEPA intended these published criteria for lakes and streams to serve as a starting point for States and others to develop more refined nutrient criteria to protect designated uses. States and others are now utilizing ongoing research to determine either: (1) appropriate reference conditions that represent a level of water quality which has no use impairments due to nutrient over-enrichment, or (2) quantitative relationships among nutrients and parameters that are more directly related to or descriptive of the particular designated use. Our goal is to provide a critical linkage between researchers and policy-makers such that: (1) researchers understand how scientific studies can be translated into water quality criteria, and (2) regulatory agency staff responsible for implementing the Clean Water Act have access to the latest nutrient-related science.
NB13E-02 INVITED 13:45h
A Protocol for Development of Linked and Tiered Criteria for Biota and Nutrients
Protecting or restoring aquatic life use has emerged as an important goal for establishing nutrient criteria; and more than one level of protection is needed for outstanding resource waters versus all others. Linking nutrient criteria to support of specific biocriteria and "tiering" both types of criteria for different designated uses can increase stakeholder support of criteria. The many steps and options for criteria development can be organized into a protocol. First, relations between valued ecological attributes, contaminants, and human activities must be established to warrant criteria development. Expected conditions of valued attributes, typically biological, should be defined. Then the stressor levels sustain those attributes, and certainty of sustainability, can be determined with stressor-response relationships. Keys for stakeholder support, such threshold responses and highly valued attributes, should be emphasized. Many tools can be used to refine stressor-response relationships, such as adjusting scales of observations, classifying ecosystems according to natural variability, using both single and multimetric indices, joint criteria, and inferring stressor conditions with biota. In addition, criteria calculations may vary depending upon planned methods for measuring compliance. These issues represent important points to consider and options for refinement. They will be related in the protocol and illustrated with studies of streams.
NB13E-03 INVITED 14:00h
Development of Effects-Based Nutrient Criteria using Biological Endpoints
Ohio employs biological endpoints to judge the status of aquatic life in rivers and streams. Specifically, numeric criteria derived from biological indices have been incorporated into Ohio's water quality standards for fish and macroinvertebrate communities. When appropriate, chemical-specific water quality standards derived from dose-response curves are used in concert with the biological indices to ascribe the causes and sources of impairment to polluted streams. However, water quality criteria have not been established for all polluting agents, especially those, like nutrients, that do not elicit a simple dose-response curve. In such cases, where biological impairment is observed, the linkage between the impairment and causal agent is made inferentially. Ohio EPA is currently studying the relationship between nutrient concentrations, periphytic chlorophyll a concentrations, and biological indices to ascertain whether a direct relationship exists between nutrient concentration and the biological health of fish and macroinvertebrate communities, with the eventual goal of adopting effects-based nutrient criteria in Ohio's water quality standards. Results from the first field season show a strong relationship between chlorophyll a concentrations, and physical and land use variables. Additionally, 48 h dissolved oxygen flux correlated with periphytic chlorophyll a concentrations and the degree of canopy cover.
NB13E-04 INVITED 14:15h
Response of Stream Macroinvertebrate Assemblages to Nutrients Within the Tiered Aquatic Life Use (TALU) Framework.
The US EPA's Tiered Aquatic Life Use (TALU) conceptual model uses narrative biological attributes to assign water bodies to tiers of biological condition. The model assumes that different types of biological attributes respond to increasing ecosystem degradation in a predictable manner. However, little empirical work has been done to evaluate whether attributes respond to specific types of stressors, such as nutrients, as predicted by the model. Thus, we evaluated the response of macroinvertebrate assemblage attributes to soluble reactive phosphorus (SRP) concentrations along a steep, longitudinal phosphorus gradient in the North Bosque River in central Texas. Consistent with the model, some attributes indicative of high biological integrity (e.g., percent intolerant taxa, percent EPT taxa) decreased with increasing SRP concentration. Similarly, some attribute values associated with poor conditions increased with increasing SRP concentrations. However, taxa richness peaked at intermediate SRP concentrations. Moreover, feeding group attributes, indicators of functional changes, showed no consistent pattern along the gradient. These results suggest that many of the theoretical responses to disturbance predicted by the TALU model may apply to nutrients in streams, but others may need additional scrutiny. They also demonstrate that macroinvertebrate assemblages may be useful in the development of numerical nutrient criteria.
NB13E-05 INVITED 14:30h
The Challenge of Understanding Nutrient-Biota Interactions in Agriculturally Dominated Landscapes
In 2002, the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program began a study of nutrient-biota interactions in five agricultural areas across the United States. The large-scale study component focused on nutrients, benthic assemblages, stream metabolism, and habitat. Median total nitrogen ranged from 1.1 to 2.1 mg/L and total phosphorus ranged from 0.04 to 0.46 mg/L, with highest concentrations associated with open-channel streams with minimal riparian habitat. Chlorophyll a concentrations on hard substrates (rock or wood) were not correlated with nitrogen or phosphorus, whereas chlorophyll a concentrations on fine-grained substrates and in seston were correlated with phosphorus. These relationships are influenced further by habitat variables such as suspended sediment and canopy. Preliminary analysis indicates that benthic algal assemblages, based on taxa biovolumes, were influenced by habitat and nutrients in some streams, but by only habitat in others. Nutrient mass-balance calculations along a subset of stream reaches provide information on the dominant pathways and processes affecting nutrient transport. However, agriculturally-impacted streams often have variable nutrient fluxes and concentrations, making mass balance calculations in these systems more difficult. Streams in agriculturally dominated landscapes provide unique opportunities and challenges that must be adequately addressed to more accurately establish nutrient criteria.
NB13E-06 INVITED 14:45h
Seasonal algal biomass and its relation to nutrients and biological communities in Indiana
During 2002, samples were collected by the Indiana Department of Environmental Management and the U.S. Geological Survey at 38 sites in the Whitewater River and at 38 sites in the East Fork White River Basins. Samples were analyzed for algal biomass (chlorophyll a in periphyton and seston, ash-free-dry-mass in periphyton, and particulate organic carbon in seston), nutrients, habitat, and fish- and invertebrate-community data. Principal components analysis was run separately for seasonal periphyton and seston biomass samples. Initial analysis indicated that seston biomass may be a better predictor of nutrients and fish-community attributes than periphyton biomass. Seston PCA axis one scores were inversely correlated to several of the fish-community metrics. Statistically significant correlations indicated an increase in the seston biomass as the following variables decreased: total Kjehldahl nitrogen, ammonia-nitrogen, total organic carbon, and total phosphorus. Significant statistical correlations were not found between the periphyton axis scores and the biological-community attributes calculated (fish and invertebrate), habitat, or land use. However, ammonia-nitrogen and nitrate-nitrogen concentrations decreased with increases in the periphyton axis scores during late summer. The chlorophyll a data collected during this study broaden the current data used by the U.S. Environmental Protection Agency (USEPA) in USEPA Nutrient Ecoregions VI and IX.