Professor of the Graduate School
Email: mepower@berkeley.edu
Phone: (510) 643-7776
Research Description
I study food webs, primarily algal-based river food webs and their linkages to upland and estuarine ecosystems. My collaborators and I use field experiments and long-term, place-based research to investigate 1) how traits and interactions of organisms, from fishing birds and fish to algae and microbes, determine ecosystem states; and 2) why states change under different environmental regimes. Our primary field site is the South Fork Eel River, in and around the Angelo Coast Range Reserve in Mendocino Co., CA. At Angelo, we have studied how hydroclimatic variation and changes in light or nutrient-limited productivity and in web membership affect structure and dynamics of food webs, as well as the performances and interactions of species within them. Presently (2024- ) we are focusing three alternative states of algal-based food webs that develop during the biologically productive summer low flow season, depending on flows during that summer and high flows during the preceding winter. We use in situ incubations or streamside experiments to control light conditions, grazers, and successional stages of the microbiome, and in the lab, use quantitative stable isotope probing and nanoSIMS to investigate taxon-specific growth rates; rates of carbon and nitrogen fixation, and elemental transfers within microbiomes of the Eel’s dominant green macroalga, (Cladophora glomerata). High flows during the previous winter control the amount of Cladophora that proliferates the following summer. Cladophora streamers become overgrown with highly nutritious epiphytic diatoms that support grazing invertebrates, prey for fish and other predators, but only if summer base flows keep mainstem pools cool and sufficiently flushed. If drought or summer water extraction reduce flows and allow pools warm and stagnate, nutritious algal assemblages can be overgrown by potentially toxic cyanobacteria. We are investigating how flow and temperature regimes affect elemental exchanges and species interactions within attached algal microbiomes over their summer succession; how these processes and interactions with higher trophic levels mediate transitions among alternate algal food webs, and the consequences for linkages among river, upland, and estuarine food webs.
Selected Publications
Rossi, G.J., Bellmore, J.R., Armstrong J.B., Jeffres, C., Naman, S.M., Carlson, S.M., Grantham, T.E., Kaylor, J.M., White, S., Katz, J., Power, M.E. 2024. Foodscapes for Salmon and Other Mobile Consumers in River Networks. 2024. BioScience 0, 1–15 https://doi.org/10.1093/biosci/biae064
Power, M.E., S. Chandra, P. Gleick and W.E. Dietrich. 2024. Anticipating responses to climate change and planning for resilience in California's freshwater ecosystems. PNAS 2024 Vol. 121 No. 32 e2310075121. https://www-pnas-org.libproxy.berkeley.edu/doi/10.1073/pnas.2310075121
Dralle, D. N. Dralle, G. Rossi, P. Georgakakos, W. J. Hahm, D. M. Rempe, M. Blanchard, M. E. Power, W. E. Dietrich, and S. M. Carlson. 2023. The salmonid and the subsurface: Hillslope storage capacity determines the quality and distribution of fish habitat. Ecosphere. 2023;14:e4436. https://onlinelibrary.wiley.com/r/ecs2 23 pp.
Power, M.E. 2021. Synthetic threads through the web of life. PNAS 118: e2004833118, https://doi.org/10.1073/pnas.2004833118.
Bouma-Gregson, K., Olm, M.R., Probst, A.J., Karthik A., Power, M.E., and Banfield, J.F. 2019. Impacts of microbial assemblage and environmental conditions on the distribution of anatoxin-a producing cyanobacteria within a river network. International Society of Microbial Ecology (ISME) Journal (www.nature.com/ismej), DOI: https://doi.org/10.1038/s41396-019-0374-3.
Vadeboncoeur, Yvonne and Mary E. Power. 2017. Attached algae as the cryptic base of inverted trophic pyramids in freshwaters. Annual Review of Ecology, Evolution, and Systematics 48: 255-279.
Keith Bouma-Gregson, Mary E. Power and Myriam Borman. 2017. Rise and fall of toxic benthic freshwater cyanobacteria (Anabaena spp.) in the Eel river: buoyancy and dispersal. Harmful Algae 66: 79-87. http://www.sciencedirect.com/science/article/pii/S1568988317300434
Sculley, J.B., Lowe, R.L., Nittrouer, C.A., Drexler, T.M., Power, M.E. 2017. Eighty years of food web response to interannual variation in discharge recorded in river diatom frustules from an ocean sediment core. PNAS 2017 114 (38) 10155-10159
Power, M.E., Bouma-Gregson, K., Higgins, P. and Carlson, S.M. 2015. The thirsty Eel: summer and winter flow thresholds that tilt the Eel River of northwestern California from salmon-supporting to cyanobacterially-degraded states. Copeia, 2015(1): 200-211. DOI: http://dx.doi.org/10.1643/CE-14-086 URL: http://www.bioone.org/doi/full/10.1643/CE-14-086 For Special Volume, Copeia: Fish out of Water Symposium.
Power, M.E., M.S. Parker, and W.E. Dietrich. 2008. Seasonal reassembly of river food webs under a Mediterranean hydrologic regime: Floods, droughts, and impacts of fish. Ecological Monographs 78: 263-282.
Marks, J.C., M.E. Power and M.S. Parker. 2000. Flood disturbance, algal productivity, and interannual variation in food chain length. Oikos 90: 20-27.
Wootton, J.T., M.S. Parker and M.E. Power. 1996. The effect of disturbance on river food webs. Science 273: 1558-1560.
Power, M.E., D. Tilman, J. A. Estes, B.A. Menge, W.J. Bond, L.S. Mills, G. Daily, J.C. Castilla, J. Lubchenco, and R.T. Paine. 1996. Challenges in the quest for keystones. BioScience 46: 609-620.
Oksanen, T., M.E. Power and L. Oksanen. 1995. Habitat selection and consumer resources. American Naturalist 146: 565-583.
Power, M.E. 1990. Effects of fish in river food webs. Science 250: 411-415.
Power, M.E. 1990. Resource enhancement by indirect effects of grazers: armored catfish, algae, and sediment. Ecology 71:897-904.
Power, M.E., W.J. Matthews and A.J. Stewart. 1985. Grazing minnows, piscivorous bass and stream algae: Dynamics of a strong interaction. Ecology 66: 1448-1456.
Power, M.E. 1984. Habitat quality and the distribution of algae-grazing catfish in a Panamanian stream. J. Anim. Ecol. 53: 357-374.
Media
http://www.peoplebehindthescience.com/dr-mary-power/
https://www.youtube.com/watch?v=rB72Hy5AGuA
https://en.wikipedia.org/wiki/The_Serengeti_Rules
https://www.pbs.org/video/the-serengeti-rules-41dfru/