Hydrographic Variability on the Scotian Shelf During the 1990s1 by

• Main Authors: K. F. Drinkwater, B. Petrie, P. C. Smith
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: Newfoundland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.580.8517; http://archive.nafo.int/open/sc/2002/scr02-042.pdf

The temperature, salinity and nutrient conditions of the waters on the Scotian Shelf during the 1990s are described and compared to the long-term variability. Three major features are highlighted. First is the presence of cold subsurface waters throughout much of the decade in the northwest and nearshore regions of the Shelf. These cold conditions, initially established in the mid-1980s, were also observed off southern Newfoundland and in the Gulf of St. Lawrence. The temperature trends on the Scotian Shelf are believed to have resulted from downstream advection with some contribution from in situ cooling. Second was the arrival in 1997-98 of cold Labrador Slope water along the shelf break, which subsequently flooded onto the Scotian Shelf. This produced the coldest near-bottom conditions on the central and southwestern shelf in the past 30 years but was of short duration, lasting only for approximately a year. Major changes in the dissolved oxygen and nutrient concentrations accompanied the Labrador Slope water intrusion; oxygen levels increased while nutrients decreased. These changes were consistent with a longer-term event in the mid-1960s. Finally, the changes in the near surface waters are described. Of particular importance was the increase in near-surface vertical stratification due primarily to the presence of low salinity waters at the surface. The impact of these ocean climate changes on the Shelf fisheries is also briefly discussed.