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Research Interests
My principal research
interests involve ecosystem ecology and biogeochemistry, with particular
attention to aquatic environments and the movement of water through
landscapes. I am especially interested in running waters, wetlands and
floodplains because they represent an interface between aquatic and
terrestrial ecosystems that is often biologically diverse and
productive. I also like to consider ecosystem processes at the landscape
or watershed scale, and I prefer to do research that contributes to our
understanding of environmental problems or improves our ability to
manage ecosystems.
I believe that to understand how ecosystems work, we frequently need
to integrate approaches from varied disciplines such as geology,
chemistry, remote sensing, and hydrology as well as ecology. Therefore I
encourage multidisciplinary investigations that seek to improve our
understanding of ecosystems and environmental problems. Stable isotopes
are one of my favorite tools for ecological investigations.
I am presently devoting much of my time to the study of various aspects
of aquatic ecosystems in southern Michigan, including wetlands, streams,
lakes, and watersheds. I also work on tropical ecosystems in South
America and dryland river ecosystems in Australia.
Detailed descriptions of my research projects:
Nitrogen isotope tracer studies
We have performed several whole-stream isotopic enrichment experiments to
study nitrogen cycling and food webs in Michigan streams as part of an intersite comparison involving biomes throughout North America, known as
the Lotic Intersite Nitrogen Experiment (LINX). The original LINX
experiments were done in 1997-98 and the results are now published. I am
one of the principal investigators for the present intersite comparison
study that examines how human disturbances affect nitrate uptake and
retention in streams, employing approaches that were developed by the
LINX project and including many of the same investigators. Experiments were done from 2002-2006 with funding from NSF. I am working
together with Dr. Jennifer Tank and her team from the University of
Notre Dame on sites throughout the Kalamazoo River watershed.
Michigan wetland ecology & biogeochemistry
I have an ongoing research program that examines how the hydrology of
southern Michigan wetlands controls their biogeochemical and ecological
characteristics, and how hydrological changes resulting from our
changing climate may alter these ecosystems. A CAREER grant from NSF
launched me into this research area. The area around KBS is excellent
for comparative studies of wetlands because of the great diversity of
these ecosystems. We have a large database of comprehensive
hydrochemical variables in wetland waters that we are currently
analyzing, and we continue sampling wetlands each spring and fall.
A current NSF grant allows us to study alternative nitrogen uptake processes, and my former PhD student Amy
Burgin spearheaded our research on these processes in wetlands and streams. Amy and I recently published a review on this topic in Frontiers in Ecology and the Environment. Another PhD student, Lauren Kinsman, is tackling the biogeochemistry of sediment phosphorus release in lakes and wetlands, funded by a new NSF grant. Related to this work and to the LINX project is an ongoing investigation of biogeochemical processes in wetlands that experience hydrological through-flow, such as impoundments along stream courses, led by postdoc Jon O'Brien.
Zebra mussel invasions of Michigan lakes
I am working with Dr. Orlando Sarnelle of MSU's Dept. of Fisheries and
Wildlife and others to study the ecological impacts of zebra mussels, an exotic
species presently spreading into our inland lakes. We are particularly
interested in the possible link between the mussels and the recent
occurrence of noxious blue-green algal blooms in lakes that were
formerly considered to be oligotrophic (i.e., low potential for algal
production). This research has included
several experiments in large mesocosms, as well as surveys of lakes with
and without the mussels, and has been funded by the National Sea Grant
Program, the Kalamazoo Foundation, and the U.S. EPA through the Ecology
of Harmful Algal Blooms program.
Agricultural ecology
Since 1998 I have been one of the principal investigators on the
Long-Term Ecological Research project at Kellogg Biological Station,
which focuses on agricultural ecology. My role is to apply a watershed
approach to understand how land use, including agriculture and other
uses, impacts the quality of surface and subsurface waters in our
region.
A major new research initiative at MSU and KBS is the DOE-funded Great Lakes Bioenergy Research Center. At KBS we are investigating the environmental sustainability of proposed biofuel crops, ranging from conventional corn through grass monocultures and prairie polycultures and even tree plantations. I am leading the biogeochemical and hydrological aspects of this work, together with Phil Robertson.
Tropical rivers & floodplains
Much of my previous research has focused on
South American rivers and
floodplains, and I have had the opportunity to work on diverse topics in
several river systems. During the 1990's, I worked in the Pantanal
wetland of Brazil in collaboration with the Brazilian Center for
Agricultural Research in the Pantanal. My research in the Pantanal has
examined the biogeochemistry of wetland waters, methane production,
floodplain hydrology, and remote sensing of inundation. Suzanne Sippel
and I extended our work with passive microwave remote sensing to examine
inundation patterns in all of the major floodplains of the continent,
and in 2002 we published a synthesis paper on this work. Three Brazilian
PhD students have spent several months working with me on data analysis
and interpretation.
In 2002 I spent my sabbatical leave at Griffith University in
Queensland, Australia, working with Dr. Stuart Bunn on dryland river
ecosystems. We conducted a hydrological
investigation of "waterholes" (deeper channel segments with permanent
water) of the Cooper Creek system, in which we determined the relative
importance of river flooding and local groundwater inputs.I have since been involved
in science planning for rivers and watersheds of the tropical north. From July 2008 to July 2009 I will be on sabbatical in Australia, working on a new tropical rivers and waterholes project, with sponsorship from the Australian government in the form of a Commonwealth Environmental Research Fellowship.
I have been assisting with conservation planning efforts in South America
in connection with several non-governmental organizations, and my most
recent project deals with the Madre de Dios River, a tributary of the
Amazon watershed in Peru. I worked with the World Wildlife
Fund on an innovative approach to integrate several kinds of remote
sensing data to delineate floodplain ecosystems in this remote and
spectacular jungle region that is one of the "Global 200" biodiversity
hotspots. We are now developing a new project on the Napo River in Peru and Ecuador, led by my PhD student Jorge Celi; field work began in late 2007.
Outreach
Our research on water resources also results in numerous opportunities
for community outreach and involvement in local environmental issues. I
serve as President of the Kalamazoo River Watershed Council and
regularly contribute information to local governments, regulatory
agencies, NGOs, and the media. One of my Master's students (Nicole Reid)
studied the biogeochemistry of local reservoirs in the context
of nutrient loading and eutrophication. In addition, I am frequently
called upon to contribute scientific information on environmental issues
in South America and Australia. For example, I have been involved in the
scientific analysis of the impacts of a proposed industrial waterway
through the Pantanal, known as the Paran�-Paraguay Waterway or "Hidrovia",
and I have been working with several non-governmental organizations to
apply our research knowledge to conservation efforts in the region.
Grad students and postdocs
Three new doctoral students joined my group in Fall 2006: Jorge Celi, Lauren Kinsman, and Micaleila Desotelle. In addition, Jonathan O'Brien joined us as a postdoc through the MSU Center for Water Sciences, and Jason Martina is working closely with our group.
MSU web pages of interest:
Biogeochemistry Research Initiative: http://biogeochemistry.plantbiology.msu.edu/
Center for Water Sciences: http://cws.msu.edu/
Environmental research in general: http://environment.msu.edu/
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Hamilton, S.K., J. Kellndorfer, B. Lehner, and M.
Tobler. 2007. Remote sensing of
floodplain geomorphology as a surrogate for habitat diversity in a
tropical river system (Madre de Dios, Peru). Geomorphology 89: 23-38.
Hamilton, S.K., A.L. Kurzman, C. Arango, L. Jin, and G.P. Robertson. 2007. Evidence for carbon sequestration by agricultural liming. Global Biogeochemical Cycles, 21, GB2021, doi:10.1029/2006GB002738.
Burgin, A.J. and S.K. Hamilton. 2007. Have we overemphasized the role of denitrification in aquatic ecosystems? A review of nitrate removal pathways. Frontiers in Ecology and the Environment 5: 89-96.
Thieme, M., B. Lehner, R. Abell, S.K. Hamilton, J. Kellndorfer, G. Powell, and J.C. Riveros. 2007. Freshwater conservation planning in data-poor areas: An example from a remote Amazonian basin (Madre de Dios River, Peru and Bolivia). Biological Conservation 135: 500-517.
Whitmire, S. L., and S. K. Hamilton. 2005. Rapid
removal of nitrate and sulfate by freshwater wetland sediments.
Journal of Environmental Quality 34: 2062-2071.
Hamilton, S. K., and P. Gehrke. 2005. Australia's
tropical river systems: Current scientific understanding and critical
knowledge gaps for sustainable management. Marine and Freshwater
Research 56: 243-252.
Hamilton, S.K., S.E. Bunn, M. Thoms, and J.C.
Marshall. 2005. Persistence of aquatic refugia between flow
pulses in a dryland river system (Cooper Creek, Australia). Limnology
and Oceanography 50: 743-754.
Hamilton, S.K., S.J. Sippel, and S.E. Bunn.
2005. Separation of algae from detritus for stable isotope or
ecological stoichiometry studies using density fractionation in
colloidal silica. Limnology and Oceanography Methods 3: 149-157.
Sarnelle, O., A.E. Wilson, S.K. Hamilton, L.B.
Knoll, and D.F. Raikow. 2005. Complex interactions between the zebra
mussel, Dreissena polymorpha, and the harmful phytoplankter, Microcystis
aeruginosa. Limnology and Oceanography 50: 896-904.
Hamilton, S.K., J.L.Tank, D.F. Raikow, E. Siler, N.J.
Dorn, and N. Leonard. 2004. The role of instream vs. allochthonous N
in stream food webs: Modeling the results of a nitrogen isotope addition
experiment. Journal of the North American Benthological Society 23:
429-448.
Raikow, D.F., O. Sarnelle, A.E. Wilson, and S.K.
Hamilton. 2004. Dominance of the noxious cyanobacterium Microcystis
aeruginosa in low-nutrient lakes is associated with exotic zebra
mussels. Limnology and Oceanography 49: 482-487.
Mulholland, P.J., H.M. Valett, J.R. Webster, S.A.
Thomas, L.N. Cooper, S.K. Hamilton, and B.J. Peterson. 2004. Stream
denitrification and total nitrate uptake rates measured using a field
15N tracer addition approach. Limnology and Oceanography 49: 809-820.
Melack, J.M., L.L. Hess, M. Gastil, B.R. Forsberg, S.K. Hamilton, I. B.T. Lima, and E.M.L.M. Novo. 2004.
Regionalization of methane emissions in the Amazon Basin with microwave
remote sensing. Global Change Biology 10: 530-544.
Webster, J. R., P. J. Mulholland, J. L. Tank, H. M.
Valett, W. K. Dodds, B. J. Peterson, W. B. Bowden, C. N. Dahm, S.
Findlay, S. V. Gregory, N. B. Grimm, S. K. Hamilton, S. L. Johnson, E. Mart�, W. H. McDowell, J. L. Meyer, D. D. Morrall, S. A. Thomas and W.
M. Wollheim. 2003. Factors affecting nitrogen retention in streams -
an inter-biome perspective. Freshwater Biology 48: 1329-1352.
Hamilton, S.K.,
S.J. Sippel, and J.M. Melack.
2002. Comparison of inundation patterns in South American floodplains.
Journal of Geophysical Research D20. Available in electronic form; doi
10.1029/2000JD000306.
Hamilton, S.K., J.L. Tank, D.F. Raikow, W.M. Wollheim,
B.J. Peterson, and J.R. Webster. 2001. Nitrogen uptake and
transformation in a midwestern US stream: A stable isotope enrichment
study. Biogeochemistry 54: 297-340.
Peterson, B.J., W.M. Wollheim, P.J. Mulholland, J. R.
Webster, J.L. Meyer, J.L. Tank, E. Marti, W.B. Bowden, H.M. Valett, A.E.
Hershey, W.B. McDowell, W.K. Dodds, S.K. Hamilton, S. Gregory, and D.D.
Morrall. 2001. Control of nitrogen export from watersheds by
headwater streams. Science 292(5514): 86-90.
Raikow, D.F. and S.K. Hamilton. 2001. Bivalve
diets in a midwestern U.S. stream: A stable isotope enrichment study.
Limnology and Oceanography 46: 514-522.
Lewis, W.M., Jr., S.K. Hamilton, M. Rodr�guez, J.F.
Saunders, III, and M.A. Lasi. 2001. Foodweb analysis of the Orinoco
floodplain based on production estimates and stable isotope data.
Journal of the North American Benthological Society 20: 241-254.
Hamilton, S.K.,
S.J. Sippel, and J.M. Melack.
1996. Inundation patterns in the Pantanal wetland of South America
determined from passive microwave remote sensing. Archiv fur
Hydrobiologie 137: 1-23.
Hamilton, S.K.,
S.J. Sippel, and J.M. Melack.
1995. Oxygen depletion and carbon dioxide and methane production in
waters of the Pantanal wetland of Brazil. Biogeochemistry 30: 115-141.
Hamilton, S.K.,
W.M. Lewis, Jr., and S.J. Sippel.
1992. Energy sources for aquatic animals on the Orinoco River
floodplain: Evidence from stable isotopes. Oecologia 89: 324-330.
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