Observations of anomalously low crustacean zooplankton production rates along the west
coast of Vancouver Island in the spring of 2015
Akash R. Sastri1, John F. Dower2, Aidan Neill2, R., Karyn D. Suchy2, Moira Galbraith3, Kelly
V. Young3 and R. Ian Perry4
1
Ocean Networks Canada, University of Victoria, Victoria, BC, Canada. E-mail: asastri@uvic.ca
University of Victoria, Victoria, BC, Canada
3
Fisheries and Oceans Canada, Institute of Ocean Sciences, Sidney, BC, Canada
4
Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC, Canada
2
The composition of the zooplankton community along the west coast of Vancouver Island
(WCVI) is known to vary with warm and cold sea-surface temperatures (SST). Statistically,
warm years have tended to favour small ‘southern’ copepod species, while cold years favour
large, lipid-rich ‘northern’ species. Less clear is the effect that anomalous SST and
compositional changes have on crustacean zooplankton production. Here we compare a unique
set of measurements from the WCVI during warm/El Nino (2005, 2009, 2010) and cold/La Nina
(2011) years with the highly anomalous conditions in 2015. Community-level estimates of
crustacean zooplankton production rates were measured using the chitobiase method. Rates
measured in 2005 and 2009-2011 ranged from 1-10 mg C m-3 day-1, with production generally
decreasing from south to north. In spring 2015, the zooplankton community was almost totally
dominated by gelatinous plankton, while crustacean zooplankton biomass was the lowest ever
observed. These patterns were reflected in crustacean zooplankton production rates which were
typically either <1 mg C m-3 day-1 (or zero), with rates increasing from south to north. We
discuss these patterns in the context of the bio-physical conditions leading up to and during our
surveys and consider possible implications for higher trophic levels.