Grantee Research Project Results
2006 Progress Report: Quantifying Ecological Thresholds And Resilience In Stream Ecosystems
EPA Grant Number: R832444Title: Quantifying Ecological Thresholds And Resilience In Stream Ecosystems
Investigators: Hilderbrand, Robert H. , Raesly, Richard L.
Institution: University of Maryland - College Park , Frostburg State University
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 2006 through December 31, 2007
Project Period Covered by this Report: 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: Aquatic Ecosystems , Water
Objective:
Our overall objectives are to assess the consequences of landscape change on stream ecosystem structure and function and conduct futures scenarios of ecosystem change. Specifically, the objectives are to: 1) assess stream ecosystem state shifts across gradients of landscape change, 2) quantify ecosystem resilience and vulnerability to forms of landscape change, 3) identify and quantify landscape alteration thresholds causing ecosystem state shifts, and 4) develop a rigorous predictive framework to forecast changes in stream ecosystems as landscape alterations continue within watersheds.
Progress Summary:
To date, we have completed a detailed analysis of specific taxa responses to land use change and are nearly finished compiling a catalog of land use thresholds above which various genera of mayflies, stoneflies, and caddisflies are eliminated from streams and levels of land use change where their distributions change. Our preliminary results also show clear differences in aquatic invertebrate community structure as land use in the watershed surpasses 10% urban development and show that coastal plain streams are more resilient than streams in the piedmont. A separate suite of analyses designed to determine the appropriate spatial scale for using land use to assess stream conditions indicates that reach-scale measures of land use explains much less variation in measures of stream condition than do watershed-scale measures. These preliminary results indicate that management and restoration of streams must occur at the scale of the watershed because local efforts, while necessary, contribute little to the condition at a site and that actions higher in the watershed may be capable of overwhelming local site characteristics. We have also run many of the community ordinations necessary for the remainder of the project. We are finding that the suite of reference sites for benthic invertebrates on the coastal plain is much more diverse than either the piedmont or highlands and that coastal plain sites have communities similar to both piedmont and highlands, but also have reference communities much different than either. In contrast, reference fish communities for coastal plain sites and substantially different than piedmont or highlands sites, but highlands and piedmont sites share many of the same community types. Our very preliminary results are indicating that while alternate community states do exist, they occur along a continuum rather than as discrete and abrupt communities for both fish and benthic invertebrates. Finally, we have made a consensus decision on a priori conditions for minimally disturbed watersheds for each of the stream classes. These criteria now allow us to move forward with the thrust of the project to identify alternate states and community responses to land use change.
Future Activities:
We have several areas of emphasis for the next year. The most important is to finalize the definition and characterization of reference sites for comparisons. Once we are comfortable with the characterizations, we will be able to finish the community-wide analyses and linkages to land uses and stressor-responses. Completion of this will allow us to develop stream vulnerability/resilience maps as well as conduct futures scenarios of human population growth and predicted changes in stream condition.
Journal Articles:
No journal articles submitted with this report: View all 5 publications for this projectSupplemental Keywords:
risk assessment, agriculture, ecology, Mid-Atlantic, Maryland, MD, EPA Region 3,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Aquatic Ecosystem, Environmental Monitoring, Ecology and Ecosystems, Ecological Risk Assessment, 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 historyRelevant Websites:
We have created a webpage to disseminate general information, project goals, and preliminary results and publications related to the research. The link to the homepage can be found at http://www.al.umces.edu/~bhilderbrand/research/asters%20project/asters%20home.html Exit . The webpage has logged over 60 visits since it was posted in April/May.
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.