Saanich Inlet

Ecosystem Type: Aquatic
Location: SI03 (48°35.30N, 123°30.22W)

Saanich Inlet is a model ecosystem…

Saanich Inlet is a seasonally anoxic fjord opening to the Strait of Georgia on the southeast coast of Vancouver Island, British Columbia. It is approximately 24 kilometers long with a maximal basin depth of 234 meters and receives limited freshwater input from the surrounding watershed. A shallow glacial entrance sill 75 meters deep restricts circulation within interior and basin waters for most of the year. During spring and summer months, restricted circulation combined with high levels of primary productivity in surface waters lead to oxygen loss with concomitant water column stratification indicated by accumulation of methane (CH4), Ammonia (NH3) and Hydrogen Sulfide (H2S). In late summer and fall, oxygenated nutrient-rich ocean waters upwelling through the Strait cascade into Saanich Inlet shoaling anoxic bottom waters upward and transforming the redox chemistry of the water column. This process is stable on decadal time scales exhibiting a relatively narrow deviation in the depth distribution of the oxycline at different times of year. The recurring seasonal development of water column anoxia followed by deep-water renewal enables spatiotemporal profiling of microbial community structure and function across a wide range of water column redox states.

Extant monitoring efforts in Saanich Inlet are informed by an extensive archive of time series measurements spanning more than five decades and important process studies focused on trace metal cycling, methane-oxidation, denitrification, ammonia-oxidation, chemoautotrophic carbon fixation, and microbial community structure and function. Sampling and data collection are facilitated by close proximity to shore-based and marine assets including the Department of Fisheries and Oceans (DFO) Institute for Ocean Sciences (IOS) and the Victoria Experimental Network Under the Sea (VENUS) cabled observatory. Ongoing expansion of VENUS infrastructure will introduce vertical profiling and ecogenomic sensing capabilities (Environmental Sample Processor or ESP) creating a uniquely powerful and responsive platform for in situ monitoring.

References:

• Anderson, J. J. and A. H. Devol. 1973. Deep water renewal in Saanich Inlet, an intermittently anoxic basin. Estuarine and Coastal Marine Science 1:1-10.
• Binqiu, Z., C. S. Wong, and K. W. Johnson. 1992. Distribution of dissolved and particulate trace metals in anoxic seawater, Saanich Inlet, BC Canada. Chinese Journal of Oceanology and Limnology 10:75-83.
• Cohen, Y. 1978. Consumption of dissolved nitrous oxide in an anoxic basin, Saanich Inlet, British Columbia. Nature 272:235-237.
• Devol, A. H. 1978. Bacterial Oxygen-Uptake Kinetics as Related to Biological Processes in Oxygen Deficient Zones of Oceans. Deep-Sea Research 25:137-146.
• Devol, A. H. 1983. Methane oxidation rates in the anaerobic sediments of Saanich Inlet Limnology and Oceanography 28:738-742.
• Devol, A. H. and S. I. Ahmed. 1981. Are high rates of sulphate reduction associated with anaerobic oxidation of methane? Nature 291:407-408.
• Emerson, S., R. E. Cranston, and P. S. Liss. 1979. Redox species in a reducing fjord: equilibrium and kinetic considerations. Deep-Sea Research 26A:859-878.
• Emerson, S., S. Kalhorn, L. Jacobs, B. M. Tebo, K. H. Nealson, and R. A. Rosson. 1982. Environmental oxidation rate of manganese(II): bacterial catalysis. Geochimica et Cosmochimica Acta 46:1073-1079.
• Gargett, A. E., D. Stucchi, and F. Whitney. 2003. Physical processes associated with high primary production in Saanich Inlet, British Columbia. Estuarine Coastal and Shelf Science 56:1141-1156.
• Herlinveaux, R. H. 1962. Oceanography of Saanich Inlet in Vancouver Island, British Columbia. Journal of the Fisheries Research Board of Canada 19 1–37.
• Juniper, S. K. and R. O. Brinkhurst. 1986a. Bacterial facilitated chemical oceanography of Saanich Inlet, British Columbia. Mar. Ecol. Prog. Ser. 33:41-59.
• Juniper, S. K. and R. O. Brinkhurst. 1986b. Water-Column Dark CO2 Fixation and Bacterial-Mat Growth in Intermittently Anoxic Saanich Inlet, British-Columbia. Marine Ecology-Progress Series 33:41-50.
• Lilley, M. D., J. A. Baross, and L. I. Gordon. 1982. Dissolved hydrogen and methane in Saanich Inlet, British Columbia. Deep Sea Res. 29:1471-1484.
• Manning, C. C., R. C. Hamme, and A. Bourbonnais. 2010. Impact of deep-water renewal events on fixed nitrogen loss from seasonally-anoxic Saanich Inlet. Marine Chemistry 122:1-10.
• Tebo, B. M. and S. Emerson. 1985. Effect of Oxygen-Tension, Mn(Ii) Concentration, and Temperature on the Microbially Catalyzed Mn(Ii) Oxidation Rate in a Marine Fiord. Applied and Environmental Microbiology 50:1268-1273.
• Timothy, D. A. and M. Y. S. Soon. 2001. Primary production and deep-water oxygen content of two British Columbian fjords. Marine Chemistry 73:37-51.
• Walsh, D. A. and S. J. Hallam. 2011. Bacterial Community Structure and Dynamics in a Seasonally Anoxic Fjord: Saanich Inlet, British Columbia. Wiley-Blackwell Hoboken, New Jersey.
• Walsh, D. A., E. Zaikova, C. G. Howes, Y. C. Song, J. J. Wright, S. G. Tringe, P. D. Tortell, and S. J. Hallam. 2009. Metagenome of a versatile chemolithoautotroph from expanding oceanic dead zones. Science 326:578-582.
• Ward, B. B. and A. E. Kilpatrick. 1990. Relationship between substrate concentration and oxidation of ammonium and methane in a stratified water column. Cont. Shelf Res. 10:1193-1208.
• Ward, B. B., K. A. Kilpatrick, A. E. Wopat, E. C. Minnich, and M. E. Lindstrom. 1989. Methane oxidation in Saanich Inlet. Cont. Shelf Res. 9:65-75.
• Wright, J. J., K. M. Konwar, and S. J. Hallam. 2012. Microbial ecology of expanding oxygen minimum zones. Nat Rev Microbiol 10:381-394.
• Zaikova, E., D. A. Walsh, C. P. Stilwell, W. W. Mohn, P. D. Tortell, and S. J. Hallam. 2010. Microbial community dynamics in a seasonally anoxic fjord: Saanich Inlet, British Columbia. Environ Microbiol 12:172-191.