Seasonal variation in abundance and size structure of phytoplankton in Baie des Chaleurs, southwestern Gulf of St. Lawrence, in relation to physical oceanographic conditions

Michel R. Claereboudt*, Jean Côté, John C. Bonardelli, John H. Himmelman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

We investigated changes in the abundance and size structure of phytoplankton and organic seston in relation to temperature, stratification and current patterns at Gascons on the north shore of Baie des Chaleurs, eastern Canada. Phytoplankton biomass showed a general decrease during the study (May to November 1989), except for a brief diatom bloom in late October. During most of the summer, a strong temperature driven stratification was present and <5 μm cells dominated the phytoplankton community. Particles measuring <5 μm also dominated the particulate organic matter (POC and PON) throughout the year. However, only 40% of these particles could be associated with phytoplankton cells. For both particulate matter and phytoplankton, the abundance of the <5 μm size fraction was positively correlated with the Brunt-Väilsälä index of stability of the water column. Inorganic nitrogen may have limited the phytoplankton growth, as generally reported for stratified environments. Most of the biomass was probably supported by nitrogen regenerated through microbial organisms. A large bacterioplankton community was suggested by the abundance of small (<5 μm) non-phytoplanktonic particles with a low and relatively uniform C/N ratio. Larger particles were only abundant at the beginning of the study (May-June) and on one date in October. Their C/N ratios indicated they were of varied origins.

Original languageEnglish
Pages (from-to)147-157
Number of pages11
JournalHydrobiologia
Volume306
Issue number2
DOIs
Publication statusPublished - Jun 1995
Externally publishedYes

Keywords

  • Eastern Canada
  • dynamics
  • hydrodynamics
  • particulate matter
  • picoplankton
  • stratification

ASJC Scopus subject areas

  • Aquatic Science

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