Grantee Research Project Results
2004 Progress Report: Interactive Effects of Climate Change, Wetlands, and Dissolved Organic Matter on UV Damage to Aquatic Foodwebs
EPA Grant Number: R829643Title: Interactive Effects of Climate Change, Wetlands, and Dissolved Organic Matter on UV Damage to Aquatic Foodwebs
Investigators: Bridgham, Scott D. , Shmagin, Boris A. , Johnston, Carol A. , Lamberti, Gary A. , Maurice, Patricia A. , Lodge, David M.
Current Investigators: Bridgham, Scott D. , Shmagin, Boris A. , Johnston, Carol A. , Lamberti, Gary A. , Maurice, Patricia A. , Frost, Paul C , Lodge, David M.
Institution: University of Oregon , South Dakota State University , University of Notre Dame
Current Institution: University of Oregon , Natural Resources Research Institute , Trent University , University of Notre Dame
EPA Project Officer: Packard, Benjamin H
Project Period: June 24, 2002 through June 23, 2005 (Extended to June 23, 2006)
Project Period Covered by this Report: June 24, 2004 through June 23, 2005
Project Amount: $897,307
RFA: Assessing the Consequences of Global Change for Aquatic Ecosystems: Climate, Land Use, and UV Radiation (2001) RFA Text | Recipients Lists
Research Category: Climate Change , Ecological Indicators/Assessment/Restoration , Water , Aquatic Ecosystems
Objective:
The objectives of this research project are to: (1) relate dissolved organic matter (DOM) concentration and chemical characteristics in various tributaries of a relatively pristine watershed in the Lake Superior drainage basin (Ontonagon River in northern Michigan) to discharge wetland landscape characteristics, upland landscape characteristics, and stream order via multivariate analysis; (2) determine interactions among ultraviolet radiation (UVR) intensity and DOM chemistry, photodegradation, photoaggregation, and biodegradation; and (3) determine the response of stream food webs to the interactions among UVR intensity and DOM quantity and quality. We have met or exceeded all goals and objectives for Year 2 of the project.
Understanding the factors controlling UVR flux into aquatic ecosystems is critical given its deleterious effects on many ecological processes. UVR is strongly attenuated in aquatic ecosystems by DOM. Previous research suggests that the quantity and quality of DOM at the landscape scale is controlled primarily by: (1) vegetation community and soil type, with the wetland area being of particular significance; (2) flow paths through soil; (3) the discharge regimes of rivers and streams; and (4) intra system DOM degradation and production mechanisms. Climate change will likely affect each of these DOM control factors in complex ways. Although a significant amount of previous research has focused on the separate roles of DOM and UVR in aquatic ecosystems, much less is known about the interactive effects of climate change, landscape, DOM, UVR, and aquatic food webs.
Progress Summary:
Watershed Analyses
As of this summer, we completed the field component of one of the major tasks of this grant. We have sampled 35 subwatersheds in the Ontonagon River watershed a dozen times over a 2-year period. Additionally, we did an initial survey of 60 sampling locations within the Ontonagon River watershed in September 2003, on which we based our final selection of the 35 sites that were sampled seasonally. In each sample we measured DOM concentration and chemistry, dissolved and particulate nitrogen (N) and phosphorus (P), cation concentrations, particulate carbon, total suspended solids, chlorophyll, and stream pH. In addition, stream gauge height was recorded at each visit to a site, and discharge also was determined 3-4 times at each site to develop stage-discharge curves. The strength of this relationship varied among the 35 sampling sites, and for those sites with poor correlations, we will collect further data in 2005 to improve the stage-discharge curves. All water chemistry variables on these samples have been run. Thus, we have developed an extensive spatial and temporal dataset of water chemistry over the Ontonagon River watershed.
The second component to our watershed analysis is to relate DOM concentration and chemical characteristics in tributaries of the Ontonagon River to discharge, landscape characteristics, and stream order with multivariate statistics. The South Dakota State group led by Carol Johnston has entered into a GIS database the landscape characteristics of each of the 35 sub watersheds, including stream characteristics, wetland abundance and type, upland landscape characteristics, surficial geology, and topography.
As part of this analysis, we evaluated the suitability of different sources of wetland data for detecting landscape/DOC interactions in the 60-site, September 2003 sampling. Regression equations were used to relate DOC concentration and chemistry in streams with three different wetland datasets: (1) the National Wetland Inventory (NWI); (2) the National Land Cover Dataset; and (3) hydric soil data from various sources (U.S. Forest Service ecological land type phase [ELTP] soil maps, state soil geographic soil maps, and Wisconsin’s soil survey geographic maps). For the comparison of datasets, the NWI dataset predicted stream DOC concentration best, then the soil data. Some kinds of wetlands contribute DOC more than others, such as needle-leaved evergreen forested wetland and scrub-shrub wetland. A manuscript focusing on the one- time sampling of the 60 sub watersheds in the Ontonagon River in September 2003 is in the final stages of preparation.
A major product of this grant will be the evaluation of temporal and spatial controls over water chemistry (including DOM) in the 35 sub watersheds of the Ontonagon River sampled repeatedly over two years. The one remaining task that remains before we can proceed with this analysis is to collect additional stream stage-discharge data for those handful of sites where our current data do not provide a strong predictive relationship between these two variables. As we have collected stage data at each visit to a site, this will allow us to include discharge as a predictive variable in our multivariate analyses. The additional data will be collected in the spring and summer of next year.
We are considering extending the scope of the watershed analysis to examine how soil carbon (C)/N ratios affect DOM fluxes in the Ontonagon watershed. Others have previously shown very strong relationships between these variables at a number of different spatial scales. However, this objective was not in the original proposal, and we are evaluating our resources to accomplish this labor-intensive task that would need to be completed during a no-cost extension year of the grant. To accomplish this goal requires that we determine the areal coverage of the dominant soil types within the Ontonagon watershed and their respective C/N ratios. An additional hurdle to surmount is that a small portion of the watershed is in Wisconsin, which uses the standard U.S. Department of Agriculture soil classification system, but soils in the Ontonagon National Forest in Michigan are mapped using a different classification system (ELTP) that is unique to the National Forest. However, we have made significant preliminary progress on this task by mapping C/N ratios for the portion of watershed in Wisconsin using the National Soil Survey Center Soil Survey Laboratory Characterization Data. Similar soil data are not available for the majority of the watershed in Michigan because of the different classification system. This will require us to collect and analyze soil samples for their C/N ratios in the dominant soil types in the majority of the watershed. To begin this lengthy process, we determined the major ELTP hydric and upland soil types in the Michigan portion of the Ontonagon watershed, made a route map to efficiently sample the dominant soil types, and collected samples from approximately 50 sites.
Many of the streams in this region originate as lake outflows, so James Larson, as part of his dissertation research, has extended our original project objectives to compare DOM and UVR dynamics in streams with and without upstream lakes. The lake-outflow streams contained significantly less DOM and less absorbance per unit carbon (a measure of how labile the DOM is) than streams without lakes. Presumably this is caused by greater photodegradation and microbial processing of DOM occurring in lakes, possibly related to residence time. In a preliminary analysis, these differences were greater at the end of summer (August) than at the beginning (May), possibly reflecting the greater photodegradation and microbial processing occurring during the summer. He has studied longitudinal changes in DOM characteristics and UVR penetration in several streams from their lake outlet for several miles downstream. We have also incorporated the GIS landscape variables into this analysis. Furthermore, in one lake-outflow stream, James intensively measured changes in DOM characteristics with distance from the lake outflow throughout this past summer, including several sets of diurnal measurements.
UVR Mapping
Three main UV mapping activities were completed during the summer of 2004. The first project measured UV flux using plastic dosimetry strips in eight streams across a 100-m transect. Plastic dosimetry strips indicate a cumulative UV dose by changes in their absorbance characteristics, and deployed over 1-2 days allow for integrated UV measurements at different depths within a stream and under different forest canopy types. Preliminary results show fairly low within-stream variation in UVR flux but dramatic differences among streams. Among stream variance appears largely related to DOM concentration and canopy cover. A second project measured the attenuation coefficients (Kd) of UVR in six streams throughout the summer. We expected greater transparency and lower Kd values as the summer progressed, especially in streams located below up-stream lakes. These results are currently being analyzed and are planned to be presented at the annual meeting of the American Society for Limnology in February 2005. Additional in-stream measurements of Kd were taken to supplement values obtained in the summer of 2003. An analysis of this data indicates that UVR Kd values are strongly controlled by DOM concentration and percent plant canopy coverage. Furthermore, UVR exposure to benthic organisms is minimal in most stream habitats in the Ontonagon watershed because of the generally high DOM concentrations that characterize this area. A manuscript describing these results is currently in review at the Journal of the North American Benthological Society.
Hydrologic Research
The objectives of the ongoing hydrological research are to: (1) understand the forces driving the water balance for the Ontonagon watershed, including its inter-annual and seasonal dynamics, and (2) to evaluate the hydrology of the Ontonagon watershed in relation to climate. Specific tasks related to these goals are as follows:
Task 1: A nalysis of stream runoff components for the Ontonagon watershed as a whole and as the sum of smaller watersheds having different land covers.
Task 2: D escription of the multi-scale landscape influence on spatial-temporal distribution of the components of the water balance.
Task 3: A nalysis of the statistical relationship between DOM concentration and river discharge.
Progress on Task 1. This work was initiated in May 2004. A literature review was completed. Several hydrology models are being investigated:
- Computing Flood Discharges for Small Ungaged Watersheds—Michigan Department of Environmental Quality (http://www.michigan.gov/deq/ Exit ) method that uses the SCS Curve Number approach in a customized Excel spreadsheet to compute stream discharge.
- Generalized Watershed Loading Functions (GWLF)—an export coefficient model developed at Cornell University (Haith and Shoemaker, 1987).
- GWLF for Excel—http://www.eeb.cornell.edu/biogeo/usgswri/usgswri.htm Exit .
- AVGWLF—a GIS-based version of GWLF developed for Pennsylvania.
- BasinSIM—a model developed by the Virginia Institute for Marine Science based on GWLF that can simulate organic C loadings (http://www.vims.edu/bio/models/basinsim.html Exit ).
- SWAT
Graduate student Zhiyu Zheng is investigating methods for applying hydrologic models and GIS analysis methods to the GIS data we have assembled for the Ontonagon watershed. He calculated the curve numbers for several headwater watersheds monitored by the U.S. Geological Survey (USGS) to begin developing discharge modeling for the Ontonagon watershed.
Progress on Task 2. The spatial-temporal distribution of hydrological characteristics were analyzed at four spatial levels (United States conterminous, U.S. Great Lakes basin, Upper Michigan, and Ontonagon watershed) using different sets of hydrological data obtained from USGS gauging station records. The work focused primarily on Upper Michigan and Ontonagon watersheds and also the interconnection of all four levels.
For Upper Michigan we compiled a data matrix of monthly stream discharges for 45 USGS gauging stations with observations of 2 to 50 years and drainage area from 21 to 1340 sq. mi. From this massive dataset we extracted five initial matrixes with mutual time intervals: 1946-1969, 1954-1993, 1955-1969, 1955-1978, and 1974-1999. Factor analysis of the matrices yielded two or three factors for different time intervals and assemblages of watersheds. The spatial distribution of distinct watershed groups was reasonably stable, regardless of the time period analyzed. All typical time series for the region have four seasons, with slightly different factor loadings for the winter season (months October-February) and some differences across groups in month composition for other seasons.
A data set of 49 stations with miscellaneous observations (i.e., stream observations completed during some kind of research project that were subsequently catalogued by Michigan or Wisconsin Geological Surveys) for Upper Michigan and neighboring territories was also compiled, with drainage areas ranging from 5 to 358 sq mi. The combination of this Upper Michigan data set with results for the Ontonagon watershed will allow us to put miscellaneous observations from the Upper Michigan area and field discharge measurement on streams on a hydrologically comparable level as if they were obtained in a mutual time period.
During the final stage of research, all hydrological results from the time series and miscellaneous observations will be compared with ecoregional maps and landscape properties. We have initiated this work for the U.S. Great Lakes basin, using monthly proportional distribution to characterize regional units with water balance differences in relation to Omernik ecoregions.
The hydrological regime for the conterminous United States and U.S. Great Lakes basin is being connected with global climatic processes with use of teleconnection indices (Atlantic oscillation, Antarctic oscillation, North Atlantic oscillation, and North Pacific oscillation).
Progress on Task 3. The discharge-DOM relationships generated by this project (described above) will be augmented with data from USGS gauging stations mainly on streams running to the south shore of Lake Superior.
Biodegradation Experiments
In our previous annual report we described two short-term studies that examined the role of microbial community structure and the initial molecular-weight distribution of DOM in DOM biodegradation rates. These studies have resulted in two papers that are in press.
We currently are 6 months into a long-term DOM biodegradation experiment that began this past summer. In this experiment, we are asking three questions: (1) How do DOM concentration and quality interact to affect DOM biodegradation rates? (2) Does low nutrient availability constrain DOM biodegradation in some streams? (3) Is the effect of photodegradation on DOM biodegradation rates dependent on the DOM source?
We filtered water from six streams with different DOM concentration and chemistry characteristics and added a composite microbial community from all six sites to each sample. We additionally had three treatments: (1) + nutrients, (2) no nutrients, and (3) photodegraded and then biodegraded, with five replicates of each stream-treatment combination. Response variables include: short-term DOM biodegradation by determining CO2 production and bacterial production over 72 hours and long-term DOM biodegradation by measuring the change in DOM concentration until it stabilizes, with the remaining fraction indicating the recalcitrant portion of the DOM. We are also measuring changes in DOM chemistry and nutrients throughout the experiment.
Food-Web Experiments
As described in our previous annual report, we constructed a large artificial stream facility at the University of Notre Dame Environmental Research Center, at the southern edge of the Ontonagon watershed, to examine experimentally how DOM and UVR interact in controlling food-web structure in streams. The artificial stream facility consists of 24 channels fed with ground water or lake water with motorized paddles providing current. We conducted two artificial stream experiments in the summer of 2003 and two experiments in the summer of 2004.
In the first experiment this past summer, we manipulated both light quantity and quality and tracked the accumulation of organic matter in artificial streams over one month. The second experiment compared the responses of periphyton to the same concentrations of DOM from two different sources, a stream with a wetland-dominated watershed and a stream downstream of a lake outlet. Results from both experiments are still being analyzed.
All analyses have been completed for the experiments conducted during the summer of 2003. These results were used in two presentations given at the annual meetings of the North American Benthological Society and the Ecological Society of America. These experiments showed that DOM has relatively stronger effects on stream producers than UVR and there was little interaction between the two. A manuscript is currently in preparation using these data.
Future Activities:
Watershed Analyses
We have largely completed the collection of the data for this major component of the project, except for additional data from some sites to improve their stage/discharge curves. This is a huge and complicated dataset that will require extensive multivariate analysis and likely yield two to three papers, but its final analysis will require the completion of the stage/discharge curves.
If resources allow, we will examine the relationship between DOM concentration and chemistry and soil C/N ratios in the Ontonagon watershed.
UVR Mapping
Data collection has been completed for this portion of the project, and we will continue to analyze the data to write several manuscripts describing landscape controls over UVR penetration into the water column throughout the Ontonagon watershed.
Hydrologic Analyses
The continuing tasks for the hydrologic analyses are described above. For Task 1, we will choose the best basin-scale hydrologic model to predict discharge and DOM flux in the Ontonagon watershed. We will parameterize this model for the Ontonagon using our own data and the USGS data described above. Ultimately, we will use the hydrological model as a tool to synthesize the many aspects of this project so that we can predict the effects of climate and landscape on DOM concentration and UVR penetration into the water column within the Ontonagon watershed. The artificial stream experiments will allow us to qualitatively extend our results to considerations of how these factors will control stream food webs.
Task 2 is near completion, and manuscripts will be prepared from the results. This will allow us to evaluate how climate change will impact discharge within the u pper Great Lakes region.
Biodegradation-Photodegradation Experiments
We will continue sampling the long-term DOM biodegradation/photodegradation samples until we no longer see measurable change in DOM concentration. We expect this to occur sometime within the next 6 months.
Food-Web Experiments
Results from the food-web experiments in 2003 are in the process of being written for publication, and results from 2004 are still being analyzed. We may undertake one more food-web experiment in the summer of 2005, probably incorporating higher trophic levels.
Reference:
Haith DA, Shoemaker LL. Generalized watershed loading functions for stream-flow nutrients. Water Resource Bulletin 1987;23(3):471–478.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 56 publications | 14 publications in selected types | All 13 journal articles |
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Frost PC, Larson JH, Kinsman LE, Lamberti GA, Bridgham SD. Attenuation of ultraviolet radiation in streams of northern Michigan. Journal of the North American Benthological Society 2005;24(2):246-255. |
R829643 (2003) R829643 (2004) R829643 (Final) |
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Frost PC, Larson JH, Johnston CA, Young KC, Maurice PA, Lamberti GA, Bridgham SD. Landscape predictors of stream dissolved organic matter concentration and physicochemistry in a Lake Superior river watershed. Aquatic Sciences – Research Across Boundaries 2006;68(1):40-51. |
R829643 (2003) R829643 (2004) R829643 (Final) |
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Young KC, Docherty KM, Maurice PA, Bridgham SD. Degradation of surface-water dissolved organic matter: influences of DOM chemical characteristics and microbial populations. Hydrobiologia 2005;539(1):1-11. |
R829643 (2003) R829643 (2004) R829643 (Final) |
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Supplemental Keywords:
water, watersheds, groundwater, land, soil, sediments, global climate, ecological effects, organism, stressor, organics, ecosystem, scaling, terrestrial, aquatic, environmental chemistry, biology, ecology, hydrology, geology, limnology, monitoring, surveys, Great Lakes, Midwest, Michigan, MI, EPA Region 5,, RFA, Scientific Discipline, Air, Geographic Area, Water, Hydrology, Water & Watershed, climate change, State, Atmospheric Sciences, Ecological Risk Assessment, EPA Region, Watersheds, water resources, dissolved organic matter, anthropogenic processes, wetlands, environmental monitoring, global change, regional hydrologic vulnerability, aquatic food web, hydrologic models, climate models, UV radiation, vulnerability assessment, aquatic ecosystems, watershed sustainablility, Lake Superior, water quality, land and water resources, Region 5, aquatic ecology, climate variability, Global Climate Change, land use, vegetation models, ecological researchProgress 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.