Mean 2012 to 2021 winter surface conditions in the Estuary and Gulf of St. Lawrence. The survey has been taking place every year in March. Surface conditions are described by temperature, salinity and nutrient concentration (mmol/m3) interpolated on a 10km x 10km grid.

Purpose

Since many years, the Department of Fisheries and Oceans Canada (DFO) has been conducting annual surveys, at different periods of the year, in the Estuary and Gulf of St. Lawrence, each having many objectives including assessment of environmental conditions.

However, these surveys, carried out on vessels, did not cover the winter period. Since 1996, a regional monitoring program, conducted by Maurice-Lamontagne Institute scientists, is taking place in order to fill this gap. The annual helicopter survey is undertaken in the beginning of March to evaluate physical oceanographic conditions of waters up to 200 m and surface water nutrient contains.

These surveys are usually sampled from a Canadian Coast Guard helicopter but from an icebreaker in 2016 and 2017.

Data from regional monitoring programs are combined with the ones from the Atlantic Zone Monitoring Program (AZMP) to produce annual reports (physical, biological and a Zonal Scientific Advice) which are available at the Canadian Science Advisory Secretariat (CSAS), (http://www.dfo-mpo.gc.ca/csas-sccs/index-eng.htm).

Galbraith, P.S., Chassé, J., Caverhill, C., Nicot, P., Gilbert, D., Pettigrew, B., Lefaivre, D., Brickman, D., Devine, L., and Lafleur, C. 2017. Physical Oceanographic Conditions in the Gulf of St. Lawrence in 2016. DFO Can. Sci. Advis. Sec. Res. Doc. 2017/044. v + 91 p.

Devine, L., Scarratt, M., Plourde, S., Galbraith, P.S., Michaud, S., and Lehoux, C. 2017. Chemical and Biological Oceanographic Conditions in the Estuary and Gulf of St. Lawrence during 2015. DFO Can. Sci. Advis. Sec. Res. Doc. 2017/034. v + 48 pp.

Additional Information

Water sampling for nutrient analysis is done from Niskin bottles according to AZMP sampling protocol:

Mitchell, M. R., Harrison, G., Pauley, K., Gagné, A., Maillet, G., and Strain, P. 2002. Atlantic Zonal Monitoring Program sampling protocol. Can. Tech. Rep. Hydrogr. Ocean Sci. 223: iv + 23 pp.

Nitrate titration is carried out according to the following method ((nitrite + nitrate) – nitrite):

Nitrite + nitrate: Armstrong, FAJ, CR Stearns, JDH Strickland (1967) The measurement of upwelling and subsequent biological processes by means of the Technicon Autoanalyzer and associated equipment. Deep-Sea Res 14(3) 381-389.

Nitrite: American Public Health Assoc. (1971) Standard Methods for the examination of water and wastewater. 13th edition, pp. 240-243, Washington D.C.

Phosphate: Murphy, J, JP Riley (1962) A modified single solution method for the determination of phosphate in natural waters. Anal Chim. Acta 27 : 30.

Silicate: Strickland, JDH, TR Parsons (1972) A Practical Handbook of Seawater Analysis, second edition. Fish Res Board Can, Bulletin 167, 310 pp.

The surface water temperature and salinity are determined from CTD profiles.