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SLGO is the first integrated ocean observing system in Canada.
Measurements of various oceanographic variables are performed in the Estuary and Gulf of St. Lawrence in order to describe the annual and interannual variability of environmental conditions of this ecosystem. The data are interpolated to create time series for each of the fixed stations and indices of oceanographic condition of Gulf of St. Lawrence are developed from data obtained from large surveys.
Every year, the Gulf is sampled at different times of the year aboard research vessel of the Canadian Coast Guard. Various measuring instruments are deployed in order to collect information on variables such as salinity, temperature, dissolved oxygen concentration, the amount of chlorophyll a and nutrients present in the water. Sampling is done mainly using a device called a rosette which is lowered in the water to the near-bottom. Equipped with several probes which measure various variables, the rosette is also equiped with bottles which, during the ascent, are closed to collect water samples at selected depths. Net tows are also made to collect zooplankton in order to determine their abundance per species. At the time of sampling, some data are processed in real time by computer on the ship. Other data are calculated from analyzes carried out in a mobile laboratory installed on board (for example, filtration and phytoplancton concentration of the water samples, dissolved oxygen concentration by titration), but most of the results will be obtained from subsequent analyzes done in laboratories at the Maurice Lamontagne Institute.
During surveys in June and autumn, a series of 46 oceanographic stations are visited, grouped into transects that cross the Gulf, in addition to some stations between these transects and at the head of the deep channels. Additional stations are made in June on the Magdalen Shallows, paired with a survey to count mackerel eggs. In August and September, AZMP resources are combined with a multidisciplinary survey for the assessment of groundfish stocks and northern shrimp, and 500 oceanographic stations are sampled covering the entire Gulf. In addition, during the year two oceanographic stations are sampled with greater temporal frequency. These are the Rimouski station, nominally sampled once a week in summer, and the Shediac Valley station on the Magdalen Shallows, also sampled once or twice a month in summer.
In the following sections, the data from these two stations are presented as time series for a selection of the variables measured. Environmental indices calculated from data obtained from large surveys are also presented that represent the conditions of the surface, intermediate and deep layers of the Gulf. The raw data are also available by consulting the Environmental Data Archive System (EDMS) and annual reports (physical, biological, and a Zonal Scientific Advice) are available from the Canadian Science Advisory Secretariat (CSAS).
Comments or questions, contact: Peter.Galbraith@dfo-mpo.gc.ca