Coastal Ocean Climate

Gully Oceanography

Gully Map
Gully Map

The Gully is the largest submarine canyon in eastern North America and is located approximately 200 km from Nova Scotia and 45 km east of Sable Island. The Gully contains a rich diversity of marine habitats and species, including deep-sea corals and the northern bottlenose whale. In recognition of this unique marine habitat, the Gully was designated a Marine Protected Area (MPA) in May 2004.

Research is being carried out by the Ocean Sciences and Ecosystem Research Divisions to improve our understanding of oceanographic processes in the Gully. There has been a long-held belief that this is a region of enhanced biological productivity which is linked to the retention of water masses and increased vertical mixing providing significant fluxes of nutrients to the euphotic zone. The research is examining whether there are physical oceanographic features which support the potential for enhanced biological productivity. Four moorings were deployed in the Gully from April 2006 to August 2007 to measure currents, temperature and salinity. These were complemented by an extensive ship-based survey of the region measuring physical, chemical and biological properties.

For further information, contact Dr. Blair Greenan.

Reference:

Harrison, W. G., and D. G. Fenton. 1998. The Gully: A Scientific Review of its Environment and Ecosystem. Canadian Stock Assessment Secretariat Research Document 98/83, Fisheries and Oceans Canada.

Locations of bi-weekly sampling stations in AZMP
Locations of bi-weekly sampling stations in AZMP
Temperature, salinity, density (sigma-t), chlorophyll, and photosynthetically active radiation (PAR) measured with SeaHorse at HL2.
Temperature, salinity, density (sigma-t), chlorophyll, and photosynthetically active radiation (PAR) measured with SeaHorse at HL2.

Biological-Physical Coupling on the Inner Scotian Shelf

The Atlantic Zone Monitoring Program (AZMP) has sampled the Halifax Line Station 2 (HL2) approximately bi-weekly since 1998. This sentinel observing site provides a high-frequency record of oceanographic conditions on the inner Scotian Shelf.

Observations include:
  • temperature, salinity, fluorometer, and oxygen profiles derived from a Sea-Bird CTD with auxiliary sensors;
  • bottle samples for oxygen, nitrate, silicate, phosphate, and phytoplankton;
  • vertical net tows for zooplankton; and
  • a Secchi disk measurement for water clarity.

Complementary research using innovative mooring technology has improved our understanding of the linkages between short-term physical events and the biological responses on time scales of days to weeks. The onset and evolution of the spring bloom on the inner Scotian Shelf is a complex process in which nutrient inventory, vertical mixing and coastal upwelling play roles of varying importance throughout its lifetime. Fall blooms of phytoplankton can be initiated by coastal upwelling events which bring nutrients upward to the ocean surface and replenish the depleted euphotic zone during this season.

For further information, contact Dr. Blair Greenan.

References:

Greenan, B.J.W., B.D. Petrie, W.G. Harrison, and N.S. Oakey, 2004. Are the Spring and Fall Blooms on the Scotian Shelf Related to Short-Term Physical Events? Continental Shelf Research, 24, 603-625. doi:10.1016/j.csr.2003.11.006.

Greenan, B. J. W., B. D. Petrie, W. G. Harrison, and P. M. Strain. 2008. The onset and evolution of a spring bloom on the Scotian Shelf. Limnol. Oceanogr. 53: 1759-1775.