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Dr. William Hobbs

Dr. William Hobbs, Associate Scientist

Ph.D., University of Alberta, Canada (Earth and Atmospheric Sciences), 2008
M.Sc., University of Dublin, Ireland (Environmental Sciences / Limnology), 2003
B.Sc., University of British Columbia, Canada (Physical Geography), 1996

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Research and Education Interests

photo of Dr. William Hobbs

My primary research focus is to understand the biogeochemical responses of lakes to human impacts, nutrient subsidies and climate change over centennial to millennial timescales. Through the use of lake sediment records a variety of environmental proxies can be analyzed to reconstruct the environmental history of a lake ecosystem. My research uses long-term limnological datasets, diatom (microscopic algae) remains and stable isotope ecology to tease apart the evolution of these ecosystems. I am also interested in the early diagenetic environments of lake sediments, which includes the cycling of C, N, P and Si.

In addition to my research I have an interest in undergraduate education; I am involved with undergraduate student mentoring in research through the STARS program and collaborations at the University of St. Thomas and the University of Minnesota. I have given guest lectures on topics in the geosciences and environmental sciences. My goal as a science educator is to provide students with a sound understanding of the scientific process and the joy of conducting environmental research.

Nitrogen deposition to lakes of the National Parks within the Great Lakes Network

Excess deposition of reactive nitrogen from the atmosphere is a major component of global change, and ecosystem responses are widespread in both terrestrial and aquatic ecosystems. Within the Great Lakes region, nitrogen deposition is elevated but has not received much attention since the era of acid deposition research. This pilot study will explore the potential role of nitrogen in recent widespread biological changes in diatom communities in Great Lakes parks. Using nitrogen stable isotope data from archived and well-dated sediment cores, we will determine historical nitrogen trajectories for Great Lakes I&M Network lakes, relate these trajectories to measured nitrogen deposition and concentration data, and evaluate relationships between nitrogen and diatom communities.

Recent limnology of high-altitude lakes in the Ecuadorian Andes

Tropical mountain regions are already experiencing the impacts of recent warming, as evidenced by the alarming rates of decline in tropical glaciers. The proper assessment of environmental change requires that these recent changes be placed within the context of long-term natural variability. I and colleagues at Yale and Queen's University, Canada, have begun collecting sediment records from a number of lakes in the Ecuadorian Andes to test whether the rates of change to the aquatic ecosystems are comparable to those of nearby glaciers. We are also interested in records of archaeometallurgy, which can be measured through lake sediment concentrations and isotopic ratios of mercury and lead.

Carbon burial dynamics in shallow lakes, Minnesota, USA

Shallow Lakes can act as effective carbon sinks. This work revolves around the modern C-cycling of shallow lakes in turbid (algal-dominated) and clear water (aquatic plant) dominated states. We are also investigating whether the rate of C burial varies between these states. We will be looking at the recent sediments in approximately 140 lakes across the state, with a subset of 12 being studied more intensively. Learn More

Holocene paleoclimate in the Northern Great Plains, USA

Sediment records from closed-basin lakes in the climatically sensitive Northern Great Plains (NGP) have contributed significantly to our understanding of paleoclimatology in this region. A 21 m sediment core was collected in 1996 from Kettle Lake, ND, USA which is a small groundwater flow-through lake. This work uses diatom ecology and geochemical proxies of groundwater flow to reconstruct the predominant climate at decadal resolution over the last 8500 years.

Recent environmental change in alpine lakes, Rocky Mountains

Alpine lakes are sentinel ecosystems of global climate change. This work has focused on the response of diatom communities over the last ~300 years to changes in climate and atmospherically-deposited nitrogen. A large number of lakes from the Rocky Mountains in Canada and the US have been studied. When we compare the changes we see in these alpine systems with Arctic lakes, changes in alpine lakes are driven largely by nutrient deposition whereas Arctic lakes are driven by recent climate warming.

Pacific salmon, marine-derived nutrients and paleolimnology in British Columbia, Canada

Spawning Pacific salmon can provide essential vectors for large amounts of marine derived nutrients (MDN, mainly nitrogen (N) and phosphorous (P)) into freshwater nursery lakes and rivers, where carcasses may routinely contribute 20-70% of a lake's total annual N. These nutrients can be recorded by the lake ecosystem through changes in diatom communities and nitrogen stable isotopes, and archived in lake sediments. This work in BC shows that MDN is not significant contribution to the annual nutrient budget, owing to the fast flushing of BC lakes and abundance of nutrients from the large forested catchments.

Diffuse nutrient pollution, phosphorus adsorption and the Great Irish Potato famine in western Ireland

The capacity of lake sediments to retain phosphorus can provide an important buffer to eutrophication. This work looked at the ability of a shallow calcareous lake to bind and bury phosphorus from a diffuse agricultural source. Sediment cores were then used to show phosphorus inputs through time. Secondary calculations of phosphorus inputs were then made through diatom communities and P-loading calculations from census data. Using all three independent measures of eutrophication over time we reconstructed the response of the lake to population changes driven by the Great Irish Potato famine.

Representative Publications

Hobbs, WO, DR Engstrom, SP Scottler, KD Zimmer, JB Cotner. (2013) Estimating modern carbon burial rates in lakes using a single sediment sample. Limnology and Oceanography Methods. 11: 316-326.

Furze, MFA, JD Scourse, AJ Pieńkowski, F Marret, WO Hobbs, RA Carter, BT Long. (2013) Deglacial to postglacial palaeoenvironments of the Celtic Sea: lacustrine conditions versus a continuous marine sequence. Boreas. DOI: 10.1111/bor.12028

Wolfe, AP, WO Hobbs, HH Birks, JP Briner, SU Holmgren, Ó Ingólfsson, S Kaushal, GH Miller, M Pagani, JE Saros, RD Vinebrooke. (2013) Stratigraphic expressions of the Holocene-Anthropocene transition revealed in sediments from remote lakes. Earth-Science Reviews 116: 17-34.

Theissen, KM, WO Hobbs, JM Ramstack Hobbs, KD Zimmer, LM Domine, JB Cotner, S Sugita (2012). The altered ecology of Lake Christina: A record of regime shifts, land use change, and lake management from a temperate shallow lake. Science of the Total Environment 433: 336-346

Hobbs WO, JM Ramstack Hobbs, T LaFrancois, KD Zimmer, KM Theissen, MB Edlund, N Michelutti, MG Butler, MA Hanson, TJ Carlson. (2012) A 200-year perspective on alternative stable state theory and lake management from a biomanipulated shallow lake. Ecol Appl. doi: 10.1890/11-1485.1. press release

Camill P, C Umbanhowar Jr., C Geiss, WO Hobbs, M Edlund, JA Dorale, J Lynch (2012) Holocene climate change and landscape development from a low-Arctic tundra lake in the western Hudson Bay region of Manitoba, Canada In Press J Paleolimnol

Holtgrieve GW, DE Schindler, WO Hobbs, PR Leavitt, EJ Ward, L Bunting, G Chen, BP Finney, I Gregory-Eaves, S Holmgren, MJ Lisac, PJ Lisi, K Nydick, LA Rogers, JE Saros, DT Selbie, MD Shapley, PB Walsh, and AP Wolfe. (2011) A coherent signature of anthropogenic N deposition to remote watersheds of the Northern Hemisphere. Science 334 1545-1548.

Hobbs WO, AP Wolfe, RD Vinebrooke. (2011) Biogeochemical responses of two alpine lakes to climate change and atmospheric deposition, Jasper and Banff National Parks, Canadian Rocky Mountains. Can. J. Fish Aquat. 68: 1480-1494.

Hobbs WO, SC Fritz, JR Stone, JJ Donovan, EC Grimm, JE Almendinger. (2011) Environmental history of a closed-basin lake in the US Great Plains: diatom response to variations in groundwater flow regimes over the last 8500 cal yrs BP. The Holocene DOI: 10.1177/0959683611405242

O'Reilly, J, L León-Vitró, PI Mitchell, I Donohue, M Leira, W Hobbs, K Irvine (2011) 210Pb-dating of a lake sediment core from Lough Carra (Co. Mayo, western Ireland): use of paleolimnological data for chronology validation below the 210Pb dating horizon. J Environ. Radioactiv. 102: 495 499.

Phillips, VJ, VL St.Louis, CA Cooke, RD Vinebrooke, WO Hobbs. (2011) Increased mercury loading to western Canadian alpine lakes over the past 200 years. Environ Sci Technol 45: 2042-2047.

McWethy D.B., C. Whitlock, J.M. Wilmshurst, M.S. McGlone, M. Fromont, X. Li, A. Dieffenbacher-Krall, W.O. Hobbs, S.C. Fritz, E.R. Cook. (2010) Rapid landscape transformation in South Island, New Zealand following initial Polynesian settlement. Proc. Nat. Acad. Sci. 107: 21343-21348.

Hobbs, W.O., S.V. Lalonde, R.D. Vinebrooke, K.O. Konhauser, M.D. Graham, R.P. Weidman, A.P. Wolfe. (2010) Algal-silica cycling and pigment diagenesis in recent alpine lake sediments: mechanisms and paleoecological implications. J. Paleolimnol. 44: 613-628

Hobbs, W.O., R.J. Telford, H.J.B. Birks, J.E. Saros, R.R.O. Hazewinkel, B.P. Perren, É. Saulnier-Talbot, A.P. Wolfe. (2010) Quantifying recent ecological changes in remote lakes of North America and Greenland using sediment diatom assemblages. PLoS One 5(4): e10026

Cooke, C.A., W.O. Hobbs, N. Michelutti, A.P. Wolfe. (2010) Reliance on 210Pb chronology compromises the inference of pre-industrial Hg flux to lake sediments. Environ Sci Technol DOI: 10.1021/es9027925

Donohue, I., M. Leira, W. Hobbs, L. León-Vitró, J. O'Reilly, K. Irvine. (2010) Rapid ecosystem recovery from diffuse pollution after the Great Irish Famine. Ecol. Appl. 20: 1733-1743

Vinebrooke, R.D., P.L. Thompson, W.O. Hobbs, B.H. Luckman, M.D. Graham, A.P. Wolfe. (2010) Glacially mediated impacts of climate warming on primary producers in alpine lakes of the Canadian Rocky Mountains. Verh. Internat. Verein. Limnol. 30(9): 1449-1452

Cooke, C.A., A.P. Wolfe, W.O. Hobbs. (2009) Lake-sediment geochemistry reveals 1400 years of evolving extractive metallurgy at Cerro de Pasco, Peruvian Andes. Geology 37: 1019-1022.

Leavitt P.R., S.C. Fritz, N.J. Anderson, P.A. Baker, T. Blenckner, L. Bunting, J. Catalan, D.J. Conley, W.O. Hobbs, E. Jeppesen, A. Korhola, S. McGowan, K. Rühland, J.A. Rusak, G. Simpson, N. Solovieva, J. Werne. (2009) Paleolimnological evidence of the effects on lakes of energy and mass transfer from climate and humans. Limnol. Oceanogr. 54(6): 2330-2348.

Hobbs, W.O., A.P. Wolfe, W.P. Inskeep, L. Amskold and K.O. Konhauser. (2009) Epipelic diatoms from an extreme acid environment: Beowulf Spring, Yellowstone National Park, U.S.A., pp.71-84. In: Kociolek, J.P., Theriot, E.C., Stevenson, R.J. (Eds) Diatom Taxonomy, Ultrastructure and Ecology: Modern Methods and Timeless Questions. A tribute to Eugene F. Stoermer. Nova Hedwigia Beihefte 135.

Hobbs, W.O. and A.P. Wolfe. (2008). Recent paleolimnology of three lakes in the Fraser River Basin (BC, Canada): no evidence for the collapse of sockeye salmon stocks following the Hells Gate landslides. J. Paleolimnol. 40: 295-308.

Hobbs, W.O. and A.P. Wolfe (2007). Caveats on the use of paleolimnology to infer Pacific Salmon returns. Limnol. Oceanogr. 52: 2053-2061.

Wolfe, A.P, C. Cooke and W. Hobbs (2006) Are current rates of atmospheric nitrogen deposition influencing lakes in the eastern Canadian Arctic? Arct. Antarct. Alp. Res. 38 (3): 465-476.

Hobbs, W.O., K. Irvine & I., Donohue (2005) Using sediments to assess the resistance of a calcareous lake to diffuse nutrient loading. Arch. Hydrobiol. 164(1): 109-125.