Linking Ecosystem Processes to Macroinvertebrate Community Structure in Restored Stream Systems of the Minnesota River BasinEPA Grant Number: FP917092
Title: Linking Ecosystem Processes to Macroinvertebrate Community Structure in Restored Stream Systems of the Minnesota River Basin
Investigators: Dolph, Christine L
Institution: University of Minnesota - Twin Cities
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Aquatic Systems Ecology
Throughout much of the globe, human activities have resulted in drastic and pervasive alterations to many of the defining characteristics of stream systems. Recently, attempts to restore or rehabilitate degraded streams have become widespread, with well over a billion dollars a year spent on stream restoration projects in the United States alone. Despite this investment of financial resources – and the purported motivation of many restoration projects to improve ecosystem health – ecological changes following the implementation of restoration activities are rarely evaluated in a systematic fashion. In this study, I will evaluate the response of stream community structure and function to stream restoration attempts conducted in three different agricultural streams. I will seek to (1) provide estimates of the level of ecological services provided by restored streams in agroecosystems, (2) provide managers with information about the most appropriate water quality monitoring tools to gauge stream recovery, and (3) provide information about environmental variables that may determine the success of stream restoration efforts.
Recently, attempts to restore degraded stream systems have become widespread, with over a billion dollars a year spent on stream restoration projects in the United States alone. At the same time, the ecological effects of stream restoration are rarely studied in a systematic manner. My research aims to evaluate the response of both ecosystem function and invertebrate community composition to recent restoration activities conducted within agricultural streams of the Minnesota River basin.
Stream community structure and function will be evaluated within both restored and untreated (i.e., control) reaches of three different warmwater streams, all of which flow through predominantly agricultural landscapes and are located within or near the Minnesota River basin in southwestern Minnesota. Specifically, I will quantify rates of two important ecosystem processes in each of these study reaches: (1) secondary production of macroinvertebrates (i.e., the amount of macroinvertebrate biomass that is produced over time), and (2) leaf litter decomposition (the amount of coarse organic material that decays or is lost over time). Both processes critically affect energy flow in lotic systems, and are indicative of a stream’s potential to provide a number of ecological services including nutrient cycling, protection of biodiversity, and fisheries production. I will also compare patterns in these processes to patterns in macroinvertebrate community structure, and identify environmental parameters that are associated with either structural or functional measures. Differences in secondary production, leaf litter decomposition, macroinvertebrate community structure, and in-stream and riparian habitat will be compared among restored and control reaches.
Restoration activities implemented to the study streams may have a number of effects on macroinvertebrate community structure and ecosystem function. Re-vegetation of the riparian zone with deciduous trees and shrubs may increase allochthonous inputs (i.e., leaf litter) to the stream, and thereby provide an energy source for detritivore (i.e., shredder) populations. Since shredders are believed to regulate leaf decomposition, an increase in shredder production in the restored reaches could increase rates of leaf litter breakdown. On the other hand, the addition of large wood and boulders may decrease current velocity in the restored channel at high flows, resulting in lower rates of leaf breakdown due to physical fragmentation. The addition of large boulders and wood to the stream channel also may affect macroinvertebrate diversity and production by (1) directly increasing the amount of stable substrate for macroinvertebrates to colonize, (2) indirectly affecting habitat availability by causing changes in stream channel geomorphology (i.e., changes in the number of pools, substrate complexity), and (3) increasing retention of allochthonous organic matter such as leaf packs and debris dams, thereby prolonging the availability of an important energy source to detritivores.
Potential to Further Environmental/Human Health Protection:
Based on the results of this project, I expect to develop several recommendations for managers that pertain to how stream restoration projects are implemented and monitored, including (1) whether stream restoration activities at the reach scale can be expected to impact the structure or function of highly disturbed agricultural streams of the Minnesota River basin, (2) whether secondary production and/or litter decomposition could be used as tools to aid in restoration effectiveness monitoring, (3) which, if any, structural attributes of macroinvertebrate communities can be used to gauge the functional integrity of streams and therefore represent good candidate metrics for restoration assessment, and (4) which, if any, individual macroinvertebrate taxa are strongly associated with patterns in ecosystem processes and therefore represent important endpoints for conservation efforts.