Jump to main content.

Using Complementary Tools From the Ecological Toolbox to Establish and Apply Nutrient Criteria

R. Jan Stevenson

Department of Zoology, Michigan State University, East Lansing, MI 48824

Many approaches, providing complementary information, can be used to establish nutrient criteria. Reference conditions help establish expected conditions and near-natural potential. Stressor-response relationships describe incremental losses in valued ecological attributes with increasing human disturbance. Nutrient criteria developed based on these two methods and observations in hundreds of streams from the Mid-Atlantic EMAP, Michigan, and Kentucky agreed or disagreed, primarily depending on the definition of reference conditions and the desired levels of valued ecological attributes. Algal responses to nutrient concentrations in these streams were similar across ecoregions. In general, most in-stream effects of nutrients on algae were observed in a relatively narrow range of nutrient concentrations: between TP <10 and 30 ug/L and 250 and 600 ug TN/L. Changes in diatom species composition, algal biomass, and nuisance growths by the filamentous green alga Cladophora were all related to this range of enrichment. Evidence suggests that N as well as P may be regulating nuisance algae in streams.

The rationale for multiple, tiered criteria for different stream-use designations were evident in stream community responses to nutrient enrichment and corroborated with reference condition assessments. The lowest nutrient criteria would protect particularly high quality waters and a slightly higher criterion would support the fish, shellfish, and wildlife. The high variability in stream nutrient concentrations makes assessment difficult. Biological indicators of nutrient conditions, based on tolerance values of organisms, provided temporally stable indicators of nutrient conditions and are recommended to complement chemical measurements as diagnostic indicators and criteria in water quality standards.

Keywords: nutrient criteria, streams, algae, tolerance values, tiered aquatic life uses, reference condition, stressor-response relationships.

EMAP Home | About EMAP | Components | Data | Documents | Bibliography | News | Site Map

Local Navigation

Jump to main content.