A swim in the Great Bear Sea: In mid-July 2016, two friends and fellow Canadian open-water swimmers and I took part in a staged swim from the town of Ocean Falls to Bella Bella, in the waters of the Great Bear Sea along British Columbia’s central coast (www.greatbearswim.com). Over the course of two consecutive days, we swam from Ocean Falls to Bella Bella, BC, an approximate 50km distance by water. We were the first to record an official open-water swim in those waters, and likely for good reason. The water is cold in that part of the world, even in mid-July. Daily recordings taken at a McInnes Island lighthouse station, approximately 40km northeast of Bella Bella, would lead one to expect an average temperature of 13C, within a narrow range of somewhere between 12-14C (DFO, 2017). Since two of us were planning to attempt the swim without a wetsuit, the water temperature was certainly something we were concerned about, and hence monitored closely.
Our observation and measurements of warm water: As swimmers, we were relieved to arrive to surface temperatures of 15-16C, with some local reports of readings on boat thermometers registering as high as 19C. There had been some atypically warm, dry, and sunny periods in the weeks prior to our arrival, although the weather had turned to some heavy rains and more typical air temperatures the week immediately before we landed in Bella Bella. The mainly freshwater portion of the swim where we launched the swim from at the base of Ocean Falls was recorded as 14C, with hourly-sampled and logged surface temperatures displaying a gradual warming to a maximum of 16C as the water became increasingly more saline.
As an environmentalist, the surprisingly warm sea surface temperatures in the Great Bear Sea are of obvious concern. Average annual global sea surface temperatures have been on a rising trend since the early 1900s, increasing approximately 1 degree Celsius, with most of that occurring in just the past 30 years (NOAA, 2017; Huang, et al., 2015: NOAA, 2017). Would what we experienced be considered an anomalous year for sea surface temperatures, and if so, have these events become noticeably more frequent and hence becoming the new normal? The average daytime sea surface temperature for July 2016 recorded at the McInnes Island lighthouse station is the second-highest ever recorded since 1954, when record keeping began (DFO, 2017), which would certainly support that hypothesis. Furthermore, have there been any observations of how this change in surface sea temperatures is impacting this relatively intact, healthy, and globally significant ecosystem ((MacKinnon, 2003; Marcot, 1997; reviewed in McGee, Cullen & Gunton, 2010; reviewed in Price, Roburn & MacKinnon, 2009)? - Dale Robinson, Royal Roads University.
Comment from LEO BC Coordinator: Warm surface water in the fjords of BC and Southeastern Alaska during summer months is often due to warmer freshwater runoff from summer rain, but Dale's observation that the more saline areas were noticeably warmer is is interesting. Indeed, mean sea surface temperatures have been increasing both regionally and globally during the past Century or more (Figures 3 and 4). This is having a profound effect, such as on pelagic fish species in the Northeast Pacific (Cheung et al. 2015), and likely whole ecosystems in this region as well (Ainsworth et al. 2011). Changes in temperature and other variables in this region may be causing profound changes to the biological communities of Canada's Pacific Marine Ecosystems (Okey et al. 2014).
References
Ainsworth, C.H., Samhouri, J.F., Busch, D.S., Cheung, W.W., Dunne, J. and Okey, T.A., 2011. Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries. ICES Journal of Marine Science: Journal du Conseil, p.fsr043.
Cheung, W.W., Brodeur, R.D., Okey, T.A. and Pauly, D., 2015. Projecting future changes in distributions of pelagic fish species of Northeast Pacific shelf seas. Progress in Oceanography, 130, pp.19-31.
Department of Fisheries and Oceans (DFO). Government of Canada. 2017. Data from BC Lighthouses. Data set: McInnes Island, temperature. Accessed April 17, 2017; http://www.pac.dfo-mpo.gc.ca/science/oceans/data-donnees/lighthouses-phares/index-eng.html.
Huang, B., Banzon, V.B, Freeman, E., Lawrimore, J., Liu, W., Peterson, T.C., Smith, T.M., Thorne, P.W., Woodruff, S.D., Zhang, H-M. 2015. Extended Reconstructed Sea Surface Temperature (ERSST), Version 4. Data set: NCEI DSI 3649_03. NOAA, National Centers for Environmental Information. doi:10.7289/V5KD1VVF. Accessed April 17, 2017.
IPCC (Intergovernmental Panel on Climate Change). 2013. Climate change 2013: The physical science basis. Working Group I contribution to the IPCC Fifth Assessment Report. Cambridge, United Kingdom: Cambridge University Press.
MacKinnon, A. (2003). West coast, temperate, old-growth forests. The Forestry Chronicle, 79(3), 475-484.
Marcot, B.G. (1997). Biodiversity of old growth forests of the West: In Kohm, K.A., Franklin, J.F. (Eds.). Creating a forestry for the 21st century: the science of ecosystem management. Island Press, Washington, DC, pp. 87-105.
McGee, G., Cullen, A., Gunton, T. (2010). A new model for sustainable development: a case study of the Great Bear Rainforest regional plan. Environment, Development and Sustainability, 12(5), 745-762.
National Oceanic and Atmospheric Administration (NOAA). US Department of Commerce. 2017. Extended Reconstructed Sea Surface Temperature (ERSST) v4 website. Accessed April 17, 2017.
Okey, T.A., Alidina, H.M., Lo, V. and Jessen, S., 2014. Effects of climate change on Canada’s Pacific marine ecosystems: a summary of scientific knowledge. Reviews in Fish Biology and Fisheries, 24(2), pp.519-559.
Price, K., Roburn, A., MacKinnon, A. (2009). Ecosystem-based management in the Great Bear Rainforest. Forest Ecology and Management, 258(4), 495-503. doi:10.1016/j.foreco.2008.10.010
