Transcript hunt
Zooplankton biogeography as a measure of oceanographic change in Canada Basin (Arctic) Brian Hunt1, John Nelson2, Fiona McLaughlin2, Eddy Carmack2 1. Earth and Ocean Sciences , University of British Columbia 2. Institute of Ocean Sciences, Sidney, BC Arctic Climate Change • Sea ice cover has declined at a rate of 11% per decade from 1979-2007 • Sea ice extent in September 2007 was 37% less than the climatological average for the same period (Comiso et al., 2008). International Polar Year – March 2007 to March 2009 http://www.ipy.org/ Canada’s Three Oceans (C3O) Institute of Ocean Sciences Aims: 1. Produce a comprehensive view of the physical and biological structure of sub-Arctic and Arctic waters around Canada 2. Use this information as a scientific basis for a long-term Arctic Ocean monitoring strategy C3O Mandate “Address change within ocean domains, identify gateways and barriers, and evaluate the stability of boundaries separating juxtaposed oceanic domains.” C3O sampling A key directive Use zooplankton biogeography, a combination of taxonomic composition and genetic population structure, to gain insight into biological advection processes between the Arctic, Atlantic and Pacific oceans. Zooplankton Biogeography • sensitive to environmental parameters e.g. oC, S • low mobility • short life histories Excellent indicators of environmental change Changing plankton distributions in the North Sea and North Atlantic Beaugrand et al 2002 Arctic water masses http://www.whoi.edu/page.do?pid=12455&tid=441&cid=18930&ct=61&article=9206 Pacific and Atlantic Oceans have distinct zooplankton communities which can be used to trace water masses Focus on calanoid copepods North Pacific and Bering Sea • Eucalanus bungii • Neoclanus cristatus • Metridia pacifica • Calanus marshallae • Acartia longiremis Atlantic • Calanus finmarchicus Expatriate species are not reproductively active in Arctic waters, and so populations have to be constantly replenished Samples collected 2006 2007 2008 Additional samples also collected in 2002, 2003, 2004, more to be collected in 2009 Occurrence of indicator species * None observed in 2007 samples * Calanus marshallae Banks island (Frost 1976) Observations in 2002 Eucalanus bungii Neocalanus cristatus (Hopcroft et al 2005) Species population structure Genetic analysis: Distribution of H1 (Arctic) and H2 (Bering Sea) Calanus glacialis 31 23 24 32 30 18 25 29 28 22 7 6 3 8 1 4 19 17 20 10 2 14 26 21 9 16 27 33 5 15 11 12 13 Nelson et al. (in press) Major zooplankton groups 100% 90% 80% Other 70% Appendicularia 60% Limacina helicina 50% Small calanoids 40% Oithona similis 30% Large calanoids 20% 10% CB28b RS4 RN6 PP1 MK2 KBOS CB21 CB16 CB15 CB9 CB4 BL8 BL4 BL2 BI6 0% •Abundance: dominated by calanoid copepods (small and large), Oithona, and pteropods • Biomass: dominated by large calanoid copepods, pteropods, chaetognaths Ecosystem Structure An important question is “What causes between station variance?” Analysis of within year spatial patterns in zooplankton community structure in relation to measured physical and biological variables will provide insight into the consequences of environmental change Pteropods and Acidification Limacina helicina Clione limacina Photo: Ricardo Giesecke Photo: Ricardo Giesecke Role of pteropods in the Arctic Ocean • Pan-Arctic Transect (Thiabault et al 1999) - pteropods were particularly important in Canada Basin (~8% of zooplankton) • In this study Pteropods averaged 14% but up to 42% of zooplankton • Important grazers and dietary components Melting of sea ice dilutes surface seawater and decreases alkalinity Aragonite under-saturated in surface waters in eastern Canada Basin in 2008 Summary The zooplankton component of C3O: 1. Use zooplankton biogeography to monitor changing ocean circulation (may be best resolved though population genetics) 2. Provide baseline information on the structure of the pelagic ecosystem, and its physical and biological drivers Insights into the affects of: - Sea-ice loss e.g. albedo, wind induced mixing, contribution of sea ice vs pelagic algae to food web - Ocean warming - Acidification