Planktonic growth and grazing in the Columbia River plume region: a biophysical model study

N. S. Banas, E. J. Lessard, R. M. Kudela, P. Maccready, T. D. Peterson, B. M. Hickey, E. Frame

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A four-box model of planktonic nutrient cycling was coupled to a high-resolution hindcast circulation model of the Oregon-Washington coast to assess the role of the Columbia River plume in shaping regional-scale patterns of phytoplankton biomass and productivity. The ecosystem model tracks nitrogen in four phases: dissolved nutrients, phytoplankton biomass, zooplankton biomass, and detritus. Model parameters were chosen using biological observations and shipboard process studies from two cruises in 2004 and 2005 conducted as part of the River Influences on Shelf Ecosystems program. In particular, community growth and grazing rates from 26 microzooplankton dilution experiments were used, in conjunction with analytical equilibrium solutions to the model equations, to diagnose key model rate parameters. The result is a simple model that reproduces both stocks (of nutrients, phytoplankton, and zooplankton) and rates (of phytoplankton growth and microzooplankton grazing) simultaneously. Transient plume circulation processes are found to modulate the Washington-Oregon upwelling ecosystem in two ways. First, the presence of the plume shifts primary production to deeper water: under weak or variable upwelling winds, 20% less primary production is seen on the inner shelf, and 10–20% more is seen past the 100 m isobath. River effects are smaller when upwelling is strong and sustained. Second, increased retention in the along-coast direction (i.e., episodic interruption of equatorward transport) causes a net shift toward older communities and increased micrograzer impact on both the Oregon and Washington shelves from the midshelf seaward.
LanguageEnglish
Article numberC00B06
Pages1-21
Number of pages21
JournalJournal of Geophysical Research: Oceans
Volume114
Issue numberC2
DOIs
Publication statusPublished - 23 Jun 2009

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Columbia (Orbiter)
river plume
Columbia River
grazing
rivers
plumes
Rivers
phytoplankton
Phytoplankton
nutrients
upwelling water
ecosystems
biomass
shelves
zooplankton
Ecosystems
Nutrients
upwelling
Biomass
coasts

Keywords

  • oceanography
  • ecosystem modeling
  • upwelling
  • river plumes

Cite this

Banas, N. S., Lessard, E. J., Kudela, R. M., Maccready, P., Peterson, T. D., Hickey, B. M., & Frame, E. (2009). Planktonic growth and grazing in the Columbia River plume region: a biophysical model study. Journal of Geophysical Research: Oceans, 114(C2), 1-21. [C00B06]. https://doi.org/10.1029/2008JC004993
Banas, N. S. ; Lessard, E. J. ; Kudela, R. M. ; Maccready, P. ; Peterson, T. D. ; Hickey, B. M. ; Frame, E. / Planktonic growth and grazing in the Columbia River plume region : a biophysical model study. In: Journal of Geophysical Research: Oceans. 2009 ; Vol. 114, No. C2. pp. 1-21.
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Banas, NS, Lessard, EJ, Kudela, RM, Maccready, P, Peterson, TD, Hickey, BM & Frame, E 2009, 'Planktonic growth and grazing in the Columbia River plume region: a biophysical model study' Journal of Geophysical Research: Oceans, vol. 114, no. C2, C00B06, pp. 1-21. https://doi.org/10.1029/2008JC004993

Planktonic growth and grazing in the Columbia River plume region : a biophysical model study. / Banas, N. S.; Lessard, E. J.; Kudela, R. M.; Maccready, P.; Peterson, T. D.; Hickey, B. M.; Frame, E.

In: Journal of Geophysical Research: Oceans, Vol. 114, No. C2, C00B06, 23.06.2009, p. 1-21.

Research output: Contribution to journalArticle

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T1 - Planktonic growth and grazing in the Columbia River plume region

T2 - Journal of Geophysical Research: Oceans

AU - Banas, N. S.

AU - Lessard, E. J.

AU - Kudela, R. M.

AU - Maccready, P.

AU - Peterson, T. D.

AU - Hickey, B. M.

AU - Frame, E.

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N2 - A four-box model of planktonic nutrient cycling was coupled to a high-resolution hindcast circulation model of the Oregon-Washington coast to assess the role of the Columbia River plume in shaping regional-scale patterns of phytoplankton biomass and productivity. The ecosystem model tracks nitrogen in four phases: dissolved nutrients, phytoplankton biomass, zooplankton biomass, and detritus. Model parameters were chosen using biological observations and shipboard process studies from two cruises in 2004 and 2005 conducted as part of the River Influences on Shelf Ecosystems program. In particular, community growth and grazing rates from 26 microzooplankton dilution experiments were used, in conjunction with analytical equilibrium solutions to the model equations, to diagnose key model rate parameters. The result is a simple model that reproduces both stocks (of nutrients, phytoplankton, and zooplankton) and rates (of phytoplankton growth and microzooplankton grazing) simultaneously. Transient plume circulation processes are found to modulate the Washington-Oregon upwelling ecosystem in two ways. First, the presence of the plume shifts primary production to deeper water: under weak or variable upwelling winds, 20% less primary production is seen on the inner shelf, and 10–20% more is seen past the 100 m isobath. River effects are smaller when upwelling is strong and sustained. Second, increased retention in the along-coast direction (i.e., episodic interruption of equatorward transport) causes a net shift toward older communities and increased micrograzer impact on both the Oregon and Washington shelves from the midshelf seaward.

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KW - oceanography

KW - ecosystem modeling

KW - upwelling

KW - river plumes

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