Quantifying Ecological Thresholds And Resilience In Stream Ecosystems

EPA Grant Number: R832444
Title: Quantifying Ecological Thresholds And Resilience In Stream Ecosystems
Investigators: Hilderbrand, Robert H. , Raesly, Richard L.
Institution: University of Maryland , Frostburg State University
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 2006 through December 31, 2007
Project Amount: $295,079
RFA: Exploratory Research: Understanding Ecological Thresholds In Aquatic Systems Through Retrospective Analysis (2004) RFA Text |  Recipients Lists
Research Category: Ecosystems , Water , Aquatic Ecosystems


The proposed project will assess the consequences of landscape change on stream ecosystem structure and function and will conduct future scenarios of ecosystem change. Specifically, we will: (1) assess stream ecosystem state shifts across gradients of landscape change, (2) quantify ecosystem resilience to forms of landscape change, (3) identify and quantify landscape alteration thresholds causing ecosystem state changes shifts, and (4) develop a rigorous predictive framework to forecast changes in stream ecosystems as landscape alterations continue within their watersheds.


We will focus on 1st – 3rd order streams in the Chesapeake Bay drainages of Maryland. These streams have been intensively sampled by the Maryland Biological Stream Survey(MD Dept.of Natural Resources), which has amassed 10 years of quantitative data for water chemistry, fish and benthic macroinvertebrate assemblages, and physical habitat at over 2,000 randomly selected sampling sites across the state and spanning a gradient of land uses and stream types. Ecosystem shifts to alternative states will be determined by multivariate ordination comparing structural and functional composition of sites to those residing in minimally disturbed watersheds. Statistical analyses will identify the form and intensity of landscape alteration experienced by sites that are able to maintain similarity to sites from minimally disturbed watersheds. The results will be used to (a) construct models to understand and predict ecosystem states, given patterns of land use in watersheds, (b) create stream vulnerability maps for a diversity of human disturbances, and (c) forecast changes in aquatic ecosystems under different human population growth scenarios.

Expected Results:

Completion of this research will result in rigorous methods for identifying alternative ecosystem states and thresholds of landscape alteration (form and intensity) that produce state shifts. Our methodology also allows assessment of resilience and vulnerability of different types of streams to a diversity of landscape alterations. We focus on Maryland streams because of its diversity of landforms and land uses, high rates of human population growth, and a very rich and long-term dataset on aquatics. However, landscape alteration is not unique to Maryland watersheds, hence our findings will be relevant regionally and nationally.

Publications and Presentations:

Publications have been submitted on this project: View all 6 publications for this project

Supplemental Keywords:

resilience, thresholds, stressors, aquatic ecology, streams, ecology, Mid-Atlantic,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Aquatic Ecosystem, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, anthropogenic stress, estuarine research, landscape change, ecological thresholds, anthropogenic impact, ecosystem indicators, modeling ecosystem change, aquatic ecosystems, water quality, ecosystem stress, riverine ecosystems, trophic interactions, ecosystem response, environmental history

Progress and Final Reports:

  • 2006 Progress Report
  • Final