An Integrative Aquatic Ecosystem Indicator
EPA Grant Number:
An Integrative Aquatic Ecosystem Indicator
Stemberger, Richard S.
, Miller, Eric K.
EPA Project Officer:
October 1, 1998 through
June 30, 2003
Ecological Indicators (1998)
The relative supply of carbon (C), nitrogen (N) and phosphorus (P) are used to integrate watershed, lake, and pelagic zooplankton assemblages in a multi- tier ecological indicator for monitoring lake integrity. We aggregate complex species assemblages into simple ecological metrics that reflect relative elemental N and P intracellular requirements of species. We demonstrate that the ambient N:P supply ratio in lake water is a powerful predictor of the proposed zooplankton metrics which display very desirable statistical properties for indicator application with minimal sampling effort. We argue that relative C, N, and P supply in freshwater lakes is driven by external processes that involve watershed land use, vegetation cover and type, riparian development, and atmospheric inputs. The relationship between estimated watershed loadings and lake N:P supply allows one to predict expected values of zooplankton metrics that are then used to detect change relative to a reference condition. Our approach provides a means to predict an N:P supply ratio for "pre-development" conditions from landscape characterization of watershed contributions, facilitating assessment of the effects of current and proposed land use on the aquatic system. Deviations of measured lake water N:P ratios and zooplankton metrics from expected values are then used to score or index lake integrity and sustainability. Furthermore, we relate a variety of potential risks to lake ecosystem function that are associated with the assemblage type along the N:P ratio gradient. These risks include the loss of the cool-water refuge, bio-accumulation of toxins, algal turbidity, acidification and UV-B toxicity.
We propose spatially extensive studies of northeastern lake-watershed ecosystems designed to improve our understanding and conceptual integration of C, N and P cycling between components of terrestrial and aquatic ecosystems. Fifty-five lakes and their associated lake-inlet streams, and the terrestrial ecosystems in their watersheds will be studied over a 3-year period. Concurrent with lake chemical and biological measurements, we will assess the supply of C, N, and P of the dissolved and particulate fractions of lake- inlet stream and ground water in a broad sampling of selected EMAP watersheds which will provide data on variance of relative C, N, and P supply with watershed vegetation cover and land use. This information will be used with landscape characterization methods and spatially-distributed process modeling to estimate expected lake-water C, N, and P supplies from landscape analysis. The geographic analysis will include data layers typically available to land managers (e.g. geology, soil, forest composition, land use, hydrology, atmospheric deposition).
The spatially extensive sampling should improve our integration of dissolved and particulate fractions of C, N, and P with zooplankton composition and the environmental signal that they provide. The landscape characterization analysis is designed to provide a greater resolution of vegetation type, land use, and atmospheric deposition of N than what is available in the EMAP data set. High-resolution landscape analysis is necessary to provide opportunities for assessment of near-lake and riparian land-use/land- cover effects on nutrient supplies. The inlet-stream survey will provide critical information on the chemistry of lake-inlet streams relative to the composition of riparian and watershed ecosystems. These last two aspects of the research will provide the data necessary to analyze and classify watersheds according to their influence on N and P supply of materials (water and particulates) to lakes. This project will improve our understanding of resource supply (C, N, and P) interactions among the multiple ecosystem compartments, thus providing the basis for a scientifically credible and general approach to ecosystem risk assessment that uses watershed landscape information for monitoring lake ecosystem integrity and sustainability.
Publications and Presentations:
Publications have been submitted on this project: View all 26 publications for this project
Journal Articles have been submitted on this project: View all 10 journal articles for this project
zooplankton, landscape characterization, lake ecosystems, geographic analysis, ecological indicators, environmental signals, ecological metrics, EMAP watersheds
, RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Nutrients, Ecology, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Air Deposition, Drinking Water, Geology, Watersheds, Ecological Indicators, nutrient transport, aquatic ecosystem, environmental monitoring, nutrient supply, ecological effects, ecological exposure, risk assessment, EMAP, carbon cycling, algae, multi-level indicators, bioavailability, other - risk assessment, algal growth, chemical transport, ecosystem indicators, terrestrial, aquatic ecosystems, phosphorus, carbon storage, integrative indicators, lake ecosystem, landscape characterization, land use, nitrogen, atmospheric deposition
Progress and Final Reports:
1999 Progress Report
2000 Progress Report
2001 Progress Report
2002 Progress Report