RQM - CTD Data From the Lampsilis Concerted Mission (MAL2021): State of Health of the St. Lawrence 2021, 2nd Edition

The Lampsilis concerted mission of August 2021, funded by the program Odyssée Saint-Laurent of the Réseau Québec maritime (RQM), aimed to gather strategic scientific knowledge for the understanding and management of the St. Lawrence River and Gulf. This mission enabled a wide-ranging acquisition of multidisciplinary data for 14 projects centred around two main lines of research: assessing water quality, and establishing a picture of the health of St. Lawrence ecosystems, within the continuum of the St. Lawrence System.

Vertical profiles of CTD data (conductivity, temperature, depth) were made in the water column at 91 stations in the St. Lawrence River (from the city of Trois-Rivières) and its Upper Estuary (at the city of Cacouna). These profiles were taken from the surface to an average distance of around 1 m from the seabed. They include measurements of temperature, salinity, density, dissolved oxygen, light transmission, vertical stratification of the environment, turbidity and sound velocity in seawater. Discrete water samples were taken at various stations and depths to compare CTD's direct measurements with laboratory analyses of chlorophyll a concentration. This comparison was used to adjust the calibration of the fluorescence data obtained from the CTD.