Romy Léger-Daigle

Student Speaker | Étudiant.e
Zostera marina is a prominent macrophyte in the temperate North Atlantic. Eelgrasses fulfill many ecological roles in coastal waters. They consolidate seabed, attenuate wave energy, and provide a hatchery, nursery, and shelter habitat for many species. In doing so, eelgrass meadows contribute to rich coastal biodiversity. They are common coastal ecosystems along the St-Lawrence Estuary, Qc, and spread further north where intense winters shorten the growing season. In the present study, we aimed to investigate the dynamics of eelgrass meadows phenology during the ice-free growing season to understand the adaptations enabling their survival over winter. Fieldwork was conducted monthly, from June to October, on intertidal eelgrass meadows in Rimouski, Qc. Sampling and measurements were carried out at three locations: the western part of the meadow under the Rimouski river's influence, the eastern part of the meadow, and a small meadow in Pointe-au-Père, disconnected from the Rimouski meadow. Preliminary results showed that the local environmental conditions affected the seasonal dynamics of each meadow. They suggest that productivity was mostly influenced by light conditions and differed among sites. Overall, biomasses reached a peak in July, while shoot densities were stable throughout summer. Leaf surface and Fv/Fm values suggested a lower energy investment into the photosynthetic apparatus during spring to benefit shoot growth. The next steps, involving the analysis of photosynthetic pigments, might lead to a better understanding of meadows phenology at a high spatial resolution.