of Victoria
Marine phytoplankton contribute ~50% of the annual carbon fixed by primary producers on Earth, and can therefore control the carbon balance in the surface ocean, which in turn influences atmospheric CO2 concentrations and modifies global climate.
The goals of my research program are to understand the causes and consequences of variations in marine primary production, and the links between phytoplankton physiology and biogeochemical cycling in the ocean. In particular, we study the eco-physiology of carbon, nitrogen and silicon acquisition in marine phytoplankton, and the sensitivity of the individual uptake mechanisms to changing environmental conditions.
Research in The Varela Lab involves both field sampling and experimentation, and laboratory culture studies. Fieldwork on ships or seashore stations predominantly takes place in high latitude oceans, which are experiencing the most dramatic effects of climate variability, while culture work is done with ecologically relevant cold-water phytoplankton.
I hold a joint faculty position with the School of Earth and Ocean Sciences at UVic.
Giesbrecht, K.E., D.E. Varela, J. Wiktor and J.M. Grebmeier. 2019. A decade of summertime measurements of phytoplankton biomass, productivity and assemblage composition in the Pacific Arctic region from 2006 to 2016. Deep Sea Research II, 162: 93-113, https://doi.org/10.1016/j.dsr2.2018.06.010
Hernando, M., I.R. Schloss, G.O. Almandoz, G. Malanga, D.E. Varela and M. De Troch, 2018. Combined effects of temperature and salinity on fatty acid content and lipid damage in Antarctic plankton. Journal of Experimental Marine Biology and Ecology 503: 120-128, https://doi.org/10.1016/j.jembe.2018.03.004.
Crawford, D.W., A.O. Cefarelli, I.A. Wrohan, S.N. Wyatt and D.E. Varela, 2018. Spatial patterns in abundance, taxonomic composition and carbon content of phytoplankton assemblages in Subarctic and Arctic Seas. Progress in Oceanography 162: 132-159, https://doi.org/10.1016/j.pocean.2018.01.006.
Hill, V., M. Ardyna, S.H. Lee and D.E. Varela, 2018. Decadal trends in phytoplankton production in the Pacific Arctic Region from 1950 to 2012. Deep Sea Research II 152: 82-91, http://dx.doi.org/10.1016/j.dsr2.2016.12.015
Hoppe, C.J.M., N. Schuback, D. Semeniuk, K. Giesbrecht, J. Mol, H. Thomas, M.T. Maldonado, B. Rost, D.E. Varela and P.D. Tortell, 2018. Resistance of Arctic phytoplankton to ocean acidification and high irradiance. Polar Biology 41: 399-413, doi: 10.1007/s00300-017-2186-0.
Varela, D.E, M.A. Brzezinski, C.P. Beucher, J.L Jones, K.E. Giesbrecht, B. Lansard and A. Mucci, 2016. Heavy silicon isotopic composition of silicic acid and biogenic silica in Arctic waters over the Beaufort shelf and the Canada Basin. Global Biogeochemical Cycles 30: 804-824, doi: 10.1002/2015GB005277.
Suchy, K.D, J.F. Dower, D.E. Varela and M.G Lagunas, 2016. Interannual variability in the relationship between in situ primary productivity and somatic crustacean productivity in a temperate fjord. Marine Ecology Progress Series 545: 91-108, doi: 10.3354/meps11608.
Varela, D.E., D.W. Crawford, I.A. Wrohan, S.N. Wyatt, and E.C. Carmack, 2013. Pelagic primary productivity and upper ocean nutrient dynamics across Subarctic and Arctic Seas. Journal of Geophysical Research – Oceans 118: 7132–7152, doi: 10.1002/2013JC009211.
Wyatt, S.N., D.W. Crawford, I.A. Wrohan, and D.E. Varela, 2013. Distribution and composition of suspended biogenic particles in surface waters across Subarctic and Arctic Seas. Journal of Geophysical Research – Oceans 118: 6867–6880, doi: 10.1002/2013JC009214.
Sutton, J.N., D.E. Varela, M.A. Brzezinski and C.P. Beucher, 2013. Species-dependent silicon isotope fractionation by marine diatoms. Geochimica et Cosmochimica Acta 104: 300-309, doi: 10.1016/ j.gca.2012.10.057.
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