JPR Advance Access originally published online on January 19, 2007
Journal of Plankton Research 2007 29(3):219-239; doi:10.1093/plankt/fbm010
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Nutrient and phytoplankton dynamics in the Queen Charlotte Islands (Canada) during the summer upwelling seasons of 2001–2002
1 Department of Botany, University of British Columbia, 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4 2 Western and Northern Service Centre, Parks Canada Agency, 300-300 West Georgia Street, Vancouver, BC, Canada V6B 6B4 3 AMCE Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
* Corresponding Author: tpeterson{at}pmc.ucsc.edu
Received on October 31, 2006; accepted on January 8, 2007
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Abstract |
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The Queen Charlotte Islands, Canada, lie at the northern extreme of the coastal upwelling system of the eastern North Pacific Ocean (51–54°N). In this study, the first observations of spatial and inter-annual patterns in nutrient inventories, chlorophyll (Chl) a and phytoplankton assemblages are reported and related to oceanographic conditions in near-shore waters of the island archipelago. Stronger and more persistent upwelling in 2002 coincided with higher nutrient and Chl a standing stocks compared to 2001 and a higher proportion of diatoms. Dinoflagellates were more prevalent in 2001, including several potentially harmful species. At sub-seasonal scales, Chl a concentrations were greatest during downwelling conditions and smallest during upwelling conditions. On the west coast, weak water column stratification, high relative proportions of diatoms and large nutrient inventories accompanied upwelling-favourable conditions, whereas on the east coast, there was no direct relationship between the Bakun Upwelling Index and water column stability. According to redundancy analysis, variability in species composition was best explained by sea surface temperature, the depth of the euphotic zone and nutrient inventories. The east coast supported blooms of coccolithophores within protected bays, confirming previous satellite observations that showed bright patches in these areas. The data illustrate that moderate upwelling can have an important influence on near-shore algal standing stocks and species composition at the northern extreme of the upwelling system off the west coast of North America, and that topographical complexity may be important for the development of phytoplankton blooms.
Present address: Institute of Marine Sciences, University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064, USA
Present address: Rescan Environmental Services, Ltd., 1111 West Hastings St., Vancouver, BC, Canada V6E 2J3