I am fascinated by how small fluxes or low rates of processes may have disproportionate effects on ecosystem and food web processes in ecological systems. I have long been interested in how nitrogen fixation, which is assumed to have low rates in most streams and rivers, may contribute N for certain organisms or at key times of the year. Our current research in this area is funded by an NSF CAREER award (2015-2020), which is focused on addressing 3 questions: (1) do nitrogen fixation and denitrification co-exist in streams across a natural range of reactive N concentrations?, (2) do "hot spots" and "hot moments" facilitate this co-existence?, and (3) do increasing nutrient loads shift the balance to favor losses via denitrification, as has long been assumed in studies of riverine ecosystems? MS student Erin Eberhard is working on these questions in the Portneuf River drainage in SE Idaho, and in the next year we will expand our scope to consider streams across the US. We are also interested in how cross-boundary fluxes of C, commonly referred to as subsidies, and have worked to merge ecosystem and community ecology perspectives on the role of subsidies in lakes and streams in collaboration with Dr. Colden Baxter and his students in the Idaho State University Stream Ecology Center, and with funding from the Japan Society for the Promotion of Science.
News and Information about the NSF CAREER project:
Follow us on the Marcarelli Lab Blog
Story on Michigan Tech's research blog Unscripted - The Yin and Yang of Nitrogen
A Storify recap of a live twitter chat with @AmyMarcarelli and @mturesearch on 17 March 2016 - Yin-Yang of Nitrogen: #NSFCareer Researcher Amy Marcarelli
Coble AA, Marcarelli AM, Kane ES, Stottlemyer JR, Toczydlowski D. 2016. Temporal patterns of dissolved organic matter biodegradability are similar across three rivers of varying size. Journal of Geophysical Research - Biogeosciences 121:1617–1631. DOI:10.1002/2015JG003218
Mineau MM, Baxter CV, Marcarelli AM, and Minshall GW. 2012. An invasive riparian tree reduces stream ecosystem efficiency via a recalcitrant organic matter subsidy. Ecology 93:1501-1508. DOI: 10.1890/11-1700.1
Scott JT, and Marcarelli AM. 2012. Cyanobacteria in freshwater benthic environments. Pp 271-289 in: Whitton BA (ed) Ecology of the Cyanobacteria II: Their Diversity in Time and Space. Springer.
Marcarelli AM, Baxter CV, Mineau MM, Hall RO. 2011. Quantity and quality: unifying food web and ecosystem perspectives on the role of resource subsidies in freshwaters. Ecology 92:1215-1225. DOI: 10.1890/10-2240.1
Marcarelli AM, and Wurtsbaugh WA. 2007. Effects of upstream lakes and nutrient limitation on periphytic biomass and nitrogen fixation in oligotrophic, subalpine streams. Freshwater Biology 52:2211-2225. DOI: 10.1111/j.1365-2427.2007.01851.x
Marcarelli AM, Baker MA, and Wurtsbaugh WA. 2008. Is in-stream nitrogen fixation an important nitrogen source for benthic communities and stream ecosystems? Journal of the North American Benthological Society 27:186-211. DOI: 10.1899/07-027.1
Marcarelli AM, and Wurtsbaugh WA. 2006. Temperature and nutrient supply interact to control nitrogen fixation in oligotrophic streams: an experimental examination. Limnology and Oceanography 51:2278-2289. DOI: 10.4319/lo.2006.51.5.2278
Biogeochemical cycles in aquatic ecosystems are often controlled by processes in adjacent terrestrial ecosystems, and can be modified by the spatial and temporal linkages between aquatic ecosystems. Our interests in this area are rooted in my dissertation research studying how lakes control the rates and spatial dynamics of nitrogen fixation in montane watersheds by controlling the presence or absence of nitrogen-fixing cyanobacteria. As a post-doc at Idaho State, we studied linkages among land use and the hydrology, nutrient cycling, and ecosystem metabolism of the Portneuf River and its tributaries. At Michigan Tech, we have worked to quantify the potential roles of hundreds of small, first to fourth-order tributaries on the near-shore dynamics of Lake Superior, particularly through seasonal export of biodegradable organic carbon. Work in the Great Lakes has been led by Dr. Ashley Coble (PhD 2015) and in collaboration with Drs. Evan Kane and Casey Huckins, with support from the Michigan Tech Research Excellence Fund, USDA McIntire-Stennis program, the Huron Mountain Wildlife Foundation, and Michigan Space Grant.
Coble AA, Marcarelli AM, Kane ES, Huckins CJ. 2017 (Online First). Uptake of ammonium and soluble reactive phosphorus in forested streams: influence of dissolved organic matter composition. Biogeochemistry. DOI: 10.1007/s10533-016-0284-7
Baker MA, Arp CD, Goodman KJ, Marcarelli AM, Wurtsbaugh WA. 2016. Stream-lake interaction: understanding a coupled hydro-ecological system. Pp 321-348 in: Jones JB, Stanley EH (eds) Streams in a Changing Environment. Academic Press.
Bump JK, Bergman BG, Schrank AJ, Marcarelli AM, Kane ES, Risch AC, Schutz M. 2016 (Early View). Nutrient release from moose bioturbation in aquatic ecosystems. Oikos. DOI: 10.1111/oik.03591
Coble AA, Marcarelli AM, Kane ES. 2015. Ammonium and glucose amendments stimulate dissolved organic matter mineralization in a Lake Superior tributary. Journal of Great Lakes Research 41:801–807. DOI:10.1016/j.jglr.2015.05.015
Bechtold HA, Marcarelli AM, Baxter CV, and Inouye RS. 2012. Effects of N, P and organic carbon on stream biofilm nutrient limitation and uptake in a semi-arid watershed. Limnology and Oceanography 57:1544-1554. DOI: 10.4319/lo.2012.57.5.1544
Marcarelli AM, Van Kirk RW, and Baxter CV. 2010. Predicting effects of hydrologic alteration and climate change on ecosystem metabolism in a western U.S. river. Ecological Applications 20:2081-2088. DOI: 10.1890/09-2364.1
Marcarelli AM, and Wurtsbaugh WA. 2009. Habitat and seasonal variations in nitrogen fixation in linked stream-lake ecosystems. Biogeochemistry 94:95-110. DOI: 10.1007/s10533-009-9311-2
We have a long-standing interest in understanding how ecosystem processes can improve planning and monitoring of stream restoration and mitigation efforts. Our projects in this area have been diverse; for example, we have tested the underlying assumptions of the practice of nutrient supplementation to mitigate for declines of Pacific Salmon by studying responses of stream nutrient uptake and metabolism, in collaboration with Colden Baxter, Scott Collins, Mark Wipfli, Andre Kohler, and Jonathan Ebel (MS 2012). In the upper Midwest, we have studied how ecosystem processes like organic matter retention, decomposition, ecosystem metabolism, and nutrient uptake may be used to monitor diverse stream restoration activities like culvert replacements, stream sediment removal, and channel reconstruction following removal of mine tailings, including work led by work by Jamie Olson (MS 2014). The funding for these projects has come from USDA Forest Service, University of Michigan Water Center with funds from the Erb Foundation, the Huron Mountain Wildlife Foundation, National Fish and Wildlife Foundation, the Shoshone-Bannock Tribes, Bonneville Power Administration, and Idaho Fish and Game.
Olson JC, Marcarelli AM, Timm AL, Eggert SL, Kolka RK. In press. Evaluating the effects of culvert designs on ecosystem processes in northern Wisconsin streams. River Research and Applications.
Collins SF, Baxter CV, Marcarelli AM, Wipfli MS. 2016. Effects of experimentally added salmon subsidies on resident fishes via direct and indirect pathways. Ecosphere 7:e01248. DOI:10.1002/ecs2.1248
Marcarelli AM, Huckins CJ, Eggert SL. 2015. Sand aggradation alters biofilm standing crop and metabolism in a low-gradient Lake Superior tributary. Journal of Great Lakes Research 41:1052-1059. DOI:10.1016/j.jglr.2015.09.004
Collins SF, Marcarelli AM, Baxter CV, Wipfli MS. 2015. A critical assessment of the ecological assumptions underpinning compensatory mitigation of salmon-derived nutrients. Environmental Management 56:571-586. DOI: 10.1007/s00267-015-0538-5
Ebel JD, Marcarelli AM, Kohler AE. 2014. Biofilm nutrient limitation, standing crop, and metabolism responses to experimental application of salmon carcass analog in Idaho streams. Canadian Journal of Fisheries and Aquatic Sciences 71:1796-1804. DOI: 10.1139/cjfas-2014-0266
Marcarelli AM, Baxter CV, and Wipfli MS. 2014. Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics. Ecosphere 5:69. DOI: 10.1890/ES13-00366.1
Hopkins JH, Marcarelli AM, and Bechtold HA. 2011. Ecosystem structure and function are complementary measures of water quality in a polluted, spring-influenced river. Water, Air and Soil Pollution 214:409-421. DOI: 10.1007/s11270-010-0432-y
Our lab is currently part of 3 large projects to study the ecology, spread, and control of Eurasian watermilfoil and its hybrids with native watermilfoils in the northern Great Lakes. You can find more out about this non-native species at our project website here: Arresting the Spread of Eurasian Watermilfoil (Myriophyllum spicatum) in the Great Lakes. These projects are funded by the EPA Great Lakes Restoration Initiative and the Michigan Invasive Species Grant Program, and are in collaboration with many different researchers at Michigan Tech, including Casey Huckins, Erika Hersch-Green, Guy Meadows, Pengfei Xue, and Rod Chimner. In our lab, this work has involved former postdoc Kevyn Juneau (now faculty at UW River Falls), PhD student Colin Brooks (also a project PI, located at Michigan Tech Research Institute), and MS student Ryan Van Goethem.