Research Document - 2008/034

Biological and Chemical Oceanographic conditions on the Newfoundland and Labrador Shelf during 2007

By P. Pepin, G.L. Maillet, S. Fraser, T. Shears, and G. Redmond

Abstract

We review seasonal and interannual 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 2007. The inventories of nitrate, the principal limiting nutrient, which had remained relatively low throughout most of the time series, appear to have increased somewhat in 2007. Indications of a decrease in phytoplankton abundance at Station 27 since 2002 were reversed in 2006. Phytoplankton abundance remained high in 2007, but the magnitude of the change is not statistically significant nor was it reflected along the oceanographic transects. In 2007, the overall abundance of zooplankton at Station 27 appears to have increased in many taxa, with Calanus hyperboreus, Metridia spp., and euphausids reaching their highest levels since the start of monitoring activities. The abundance of Calanus finmarchicus at Station 27 remains substantially above its lowest level (2005). On the Grand Banks, many species of small copepods were at their highest levels on record, but the abundance of Calanus glacialis and C. hyperboreus showed a substantial decrease. Furthermore, the abundances of most meroplankton, larvaceans and ostracods were below the long term average throughout the region. Although near the long term average, many carnivorous taxa have shown a consistent decreasing trend in abundance since either 2004 or 2005.

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