Detailed Overview and Site Description

Bedford Basin is a small embayment that forms the inner portion of Halifax Harbour. It is encircled by the largest urban population centre in eastern Canada. For 30 years after the establishment of the Bedford Institute of Oceanography in 1962, the Basin served as an easily accessible body of water for marine research as opportunity permitted. In 1992, regular observation was initiated to record the state of the plankton ecosystem on a sustained basis. This program of research and monitoring delineates normal conditions in the Basin and discerns ecological change over long periods of time. The Compass Buoy station (44° 41' 37" N, 63° 38' 25" W) in Bedford Basin may be considered the inshore terminus of the Halifax Line of the Atlantic Zone Monitoring Program.

Bedford Basin is an estuary with a surface area of 17 square kilometers, a volume of 0.5 billion cubic meters, a maximum depth of 71 m, and a connection to the adjoining Harbour through a narrow and shallow sill. The Basin receives freshwater from the Sackville River at an annual average inflow of 5 cubic meters per second. Additional runoff enters the Basin from the watershed which has an area of 281 square kilometers. The mean circulation is a two-layer structure where lower density surface water flows outwards to the open Atlantic, and deeper saline water flows into the Basin over the sill. The mean tidal range is 1.5 m, the ratio of tidal to freshwater volume is 109, and the flushing time is 261 hours.

Weekly measurements are made of selected properties that characterize the physical, chemical, biological and optical environments of the water column in Bedford Basin. Water temperature, nitrate concentration, phytoplankton abundance, and light attenuation are respective examples.