Trends in water temperature and salinity (A) and density of phytoplankton of two size ranges (B), Canada Basin, 2004 to 2008

Box 4. Increased stratification in the Canada Basin leading to changes in the food web.

Stratification of the water column increased throughout the Canada Basin over a recent five-year period, accompanied by a change in phytoplankton communities [127, 152]. The upper ocean layer showed trends of increased temperature and decreased salinity (Figure 18A), which combine to make this layer progressively less dense. The layer of water below this did not change in density over this period (not shown). The larger size class of phytoplankton (which would include diatoms) decreased in abundance, while the smaller types of plankton increased (Figure 18B). In addition to the trends shown, nutrient content in the upper ocean water layer decreased. Abundance of microbes (bacteria and similar organisms) that subsist on organic matter increased. Total phytoplankton biomass, however, remained unchanged.

If this trend towards smaller species of phytoplankton and microbes is sustained, it may lead to reduced production of zooplankton [5, 148], an impact that would be transmitted through the food web to birds, fish and mammals [21].

Figure 18. Trends in water temperature and salinity (A) and density of phytoplankton of two size ranges (B), Canada Basin, 2004 to 2008

Samples are from the upper ocean during summer. Points on the graphs are averages of data for 23 stations that were distributed across the Canada Basin.

From Li et al. 2009 [127]

Conservation of Arctic Flora and Fauna (CAFF) 

The data can be downloaded freely. Users are requested to reference the source.

Eamer, J., Donaldson, G.M., Gaston, A.J., Kosobokova, K.N., Lárusson, K.F., Melnikov, I.A., Reist, J.D., Richardson, E., Staples, L., von Quillfeldt, C.H. 2013. Life Linked to Ice: A guide to sea-ice-associated biodiversity in this time of rapid change. CAFF Assessment Series No. 10. Conservation of Arctic Flora and Fauna, Iceland. ISBN: 978-9935-431-25-7.

5. Michel, C., Ingram, R.G., and Harris, L.R. 2006. Variability in oceanographic and ecological processes in the Canadian Arctic Archipelago. Progress in Oceanography 71(2-4): 379-401. doi:10.1016/j.pocean.2006.09.006.

21. Michel, C., Bluhm, B., Ford, V., Gallucci, V., Gaston, T., Gordillo, F.J.L., Gradinger, R., Hopcroft, R., Jensen, N., Mustonen, K., Mustonen, T., Niemi, A., Nielsen, T.G., and Skjoldal, H.R. 2013. Marine ecosystems. Chap. 14 In Arctic biodiversity assessment. Status and trends in Arctic biodiversity. Edited by Meltofte, H. Conservation of Arctic Flora and Fauna (CAFF), Akureyri, Iceland. pp. 264-305.

127. Li, W.K.W., McLaughlin, F.A., Lovejoy, C., and Carmack, E.C. 2009. Smallest algae thrive as the Arctic Ocean freshens. Science 326(5952): 539-539. doi:10.1126/science.1179798.

148. Leu, E., Soreide, J.E., Hessen, D.O., Falk-Petersen, S., and Berge, J. 2011. Consequences of changing sea-ice cover for primary and secondary producers in the European Arctic shelf seas: Timing, quantity, and quality. Progress in Oceanography 90(1-4): 18-32. doi:10.1016/j.pocean.2011.02.004.

152. McPhee, M.G., Proshutinsky, A., Morison, J.H., Steele, M., and Alkire, M.B. 2009. Rapid change in freshwater content of the Arctic Ocean. Geophysical Research Letters 36. doi:10.1029/2009gl037525.