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Canadian Science Advisory Secretariat
Research Document - 2006/063
Biological and Chemical Oceanographic conditions on the Newfoundland and
Labrador Shelf during 2005
By Pepin, P., G.L. Maillet, S. Fraser, and D. Lane
Abstract
We review the information concerning the seasonal and inter-annual variations in
the concentrations of chlorophyll a, major nutrients, as well as the abundance
of major taxa of phytoplankton and zooplankton measured from Station 27 and
along standard transects of the Atlantic Zone Monitoring Program (AZMP) in 2005.
The timing of the spring bloom was earlier than in 2003, reversing a trend of
increasing delay in the onset of the bloom that had started in 2000, at least
over the central portion of the Newfoundland and Labrador Shelf. Deep nutrient
inventories at Station 27 remained below the 2000-01 levels but showed signs of
increased variability toward the end of 2004. Surface nutrient inventories were
higher than in 2003, possibly due to a less intense spring phytoplankton bloom
brought on by a deeper winter mixed layer and an abrupt stratification in the
spring. The abundance of the dominant zooplankton taxa at Station 27 and on the
Grand Banks reached the lowest levels encountered since the inception of the
AZMP. In contrast, zooplankton abundance levels along the Bonavista and Seal
Island transects were generally close to the maximum levels encountered. The
signal was strongest for Calanus finmarchicus, C. glacialis and C. hyperboreus,
the three species which make up the bulk of the zooplankton biomass in the
region. Although other species did show similar trends, these were generally not
statistically significant.
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