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Research Document - 2012/012

Optical, Chemical, and Biological Oceanographic Conditions in the Maritimes Region in 2009 and 2010

By C. Johnson, G. Harrison, E. Head, J. Spry, K. Pauley, H. Maass, M. Kennedy, C. Porter, I. Yashayaeva, and B. Casault

Abstract

Optical, chemical, and biological oceanographic conditions in the Maritimes Region (Georges Bank, eastern Gulf of Maine, Bay of Fundy, and the Scotian Shelf) during 2009 and 2010 are reviewed and related to conditions during the preceding year and over the longer-term, where applicable. In addition to descriptions of Atlantic Zonal Monitoring Program (AZMP) core data collections (fixed stations, seasonal sections, ecosystem trawl or groundfish surveys, remote-sensing), some data from outside the region are discussed also to provide the larger, zonal perspective.

Optical properties at the Maritimes fixed stations in 2009 and 2010 differed by site but were, for the most part, comparable to conditions observed in previous years.

Winter-time nutrient inventories in surface waters at Halifax-2 were normal in 2009 but slightly below average in 2010; inventories were higher than normal in 2009 and 2010 at Prince-5. Deep (>50 m) nutrient inventories in spring were lower than normal in the Emerald Basin and off the western Shelf in 2010 but were higher than normal in summer. Overall, annual nutrient anomalies were at record high levels in 2009 and near record low levels in 2010 in Maritimes waters.

The seasonal growth cycle of phytoplankton in the Maritimes Region 2009 was unremarkable, i.e. similar to conditions seen previously. In 2010, however, the spring bloom started much earlier than usual and was similar to the conditions seen in 1999 when AZMP started. 2010 may be a strong year-class for both cod and haddock, as 1999, based on preliminary data analysis. Phytoplankton community structure at the two fixed stations in 2009 and 2010 was similar to that seen in previous years with diatoms dominating during the spring bloom and flagellates dominating in summer-fall at Halifax-2 and diatoms dominating the community at Prince-5 year-round. The relative abundance of ciliates increased at both stations in 2009 and 2010. Overall, annual phytoplankton anomalies suggested conditions were near normal in 2009 and 2010 despite the early spring bloom in 2010.

Annual zooplankton anomalies were lower than normal in 2009 and near normal in 2010, and the timing of the seasonal biomass peak was normal or near normal in both years. The abundance of the dominant copepod Calanus finmarchicus and of total copepods were lower than normal throughout most 2010 at Halifax-2, but both exhibited strong peaks in April and June. Zooplankton biomass and abundance anomalies were spatially variable in 2010, with higher values in the Cabot Strait and Eastern Scotian Shelf.

The unusually low NAO in 2010 may portend environmental changes in 2011-2012.

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