Influence of Winter Disturbances on Eelgrass Meadow Cover and the Structure of Associated Communities in the Subarctic St. Lawrence Marine Estuary (Quebec, Canada), 2024–2025

This dataset documents the influence of winter disturbances on eelgrass meadow cover and the structure of associated benthic communities in the subarctic maritime estuary of the St. Lawrence, Quebec, Canada. Data were collected between 2024 and 2025 at Anse à la Peinture, an intertidal eelgrass meadow located on the north shore of the St. Lawrence maritime estuary. The dataset includes measurements of eelgrass meadow cover obtained through drone surveys conducted in August 2024 and August 2025. Eight 60 × 60 m subareas were randomly selected within the eelgrass habitat (with a minimum initial cover of 40%) to assess spatial variations in meadow cover. Lower-altitude drone flights were also carried out to map an area of approximately 1,500 m², for which comparisons between August 2024 and May 2025 were performed. These comparisons enabled the identification of three substrate status categories: Stable (persistence of foundation species cover), Abraded (complete loss of cover following winter), and Reference (natural absence of foundation species before and after the winter season). Based on these substrate statuses, biological sampling was conducted using 20 × 20 cm quadrats and mesh nets (for epibionts) to characterize the communities associated with eelgrass meadows. The analyses distinguish between two biological compartments: species associated with the aboveground biomass of eelgrass meadows (eelgrass leaves) and species associated with the benthic substrate. These data were collected as part of a Master’s research project in Renewable Resources at the Université du Québec à Chicoutimi (UQAC), conducted by Mathis Bernard. They contribute to a better understanding of the effects of coastal winter disturbances on eelgrass meadows and associated benthic communities in subarctic environments.

This project is part of the Coastal Environmental Baseline Program Initiative under the Oceans Protection Plan of Fisheries and Oceans Canada.