Microbial indicators of biological integrity and nutrient stress for aquatic ecosystems

EPA Grant Number: R825868
Title: Microbial indicators of biological integrity and nutrient stress for aquatic ecosystems
Investigators: Grover, James P. , Chrzanowski, Thomas H.
Institution: The University of Texas at Arlington
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 1997 through August 31, 2000
Project Amount: $748,000
RFA: Ecosystem Indicators (1997) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems


Changes in nutrient (N and P) inputs to aquatic ecosystems dramatically alter community composition and consequently ecosystem function. Alterations of community structure usually begin at the microbial level as it is here that organisms have mechanisms for extracting from the external milieu elements that are required to synthesize new biomass. Clearly, all organisms have requirements for nutrients that must be met if they are to persist and organisms differ in their competitive ability to sequester these nutrients. Thus it follows logically that when environments differ in nutrient conditions, there will be differences in community composition.


We propose to examine several chemical and biological variables that may provide not only a broadly applicable approach to understanding the biological consequences of nutrient loading in aquatic systems, but may also provide a means of predicting the resulting community structure. We base our approach on recent advances in aquatic microbial ecology and on theory developed in the rapidly expanding field of ecological stoichiometry. The indicators we will examine are (1) seston C:N:P ratio; (2) species-level responses of algae to nutrient bioassays; (3) community-level responses of bacteria to nutrient bioassays; (4) community structure of algae; (5) community structure of bacteria; and (6) the estimated ratio of algal to bacterial specific growth rates. Our general hypothesis is that these indicators will reflect nutrient-related stresses, including eutrophication and alterations of nutrient loading ratios.


We will employ a standard protocol for sampling events, consisting of sampling standard limnological and water quality parameters, seston stoichiometric analysis, and algal and bacterial dilution bioassays to identify limiting nutrients and estimate in situ growth rate and degree of nutrient limitation. Over 3 years, this protocol will be applied in two warm temperate reservoirs in Texas where previous work suggests differing patterns of nutrient limitation, and in two cool temperate lakes, one of which is pristine, and one which is experimentally eutrophied.

Expected Results:

We hope to demonstrate that the proposed indicators sensitively reveal seasonal shifts in nutrient limitation, interannual, inter-lake, and regional differences in nutrient stress and loading, and the effects of experimental eutrophication. The microbial indicators we propose should have wide applicability in nearly all aquatic habitats, and are based on ecosystem components with very rapid responses to environmental changes. These indicators are short-term, and thus feasible to repeat at larger temporal and spatial scales. Our study will reveal whether these short-term indicators adequately reflect whole-lake and larger-scale responses to nutrient stresses

Publications and Presentations:

Publications have been submitted on this project: View all 25 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

water, ecological effects, metabolism, ecosystem, indicators, ecology, limnology, analytical, Central, Texas, TX, Canada, RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Limnology, Nutrients, Aquatic Ecosystems & Estuarine Research, exploratory research environmental biology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Aquatic Ecosystem, Microbiology, Ecological Effects - Environmental Exposure & Risk, Ecological Risk Assessment, Aquatic Ecosystem Restoration, Ecological Indicators, aquatic, biological activity, ecological condition, ecological effects, interactive stressors, nutrient supply, eutrophication, hydrological stability, ecological exposure, adverse impacts, ecosystem assessment, wetland eutrophication, aquatic biota , nutrient loading, algae, bioavailability, algal growth, demographic factors, ecosystem condition, molecular detection, wetland habitat, Seston C:N:P ratio, biological integrity, biotic integrity, lakes, nutrient stress, ecosystem indicators, aquatic ecosystems, ecosystem, ecosystem health, environmental indicators, environmental stress, water quality, ecological stoichiometry, biological indicators, interactive aquatic ecosystem indicator, microbial, nitrogen

Relevant Websites:

http://www.uta.edu/chrzanowski Exit EPA icon
http://www.uta.edu/grover Exit EPA icon

Progress and Final Reports:

  • 1998
  • 1999 Progress Report
  • Final Report