EGU2020-22581
https://doi.org/10.5194/egusphere-egu2020-22581
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Influence of nutrients enrichment on ecosystem functioning in a subpolar seagrass meadow

Ludovic Pascal1,2,3, Gwénaëlle Chaillou2, Pascal Bernatchez1, Christian Nozais3, and Philippe Archambault4
Ludovic Pascal et al.
  • 1Research Chair in Coastal Geoscience, Québec-Océan, Département de biologie, chimie et géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
  • 2Canada Research Chair in Geochemistry of Coastal Hydrogeosystems, Québec-Océan, Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
  • 3Québec-Océan, Département de biologie, chimie et géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
  • 4Québec-Océan, Département de biologie, Université Laval, 2325 rue de l’Université, Québec, QC, G1V 0A6, Canada

Seagrass meadows are among the most productive ecosystems in the world: they store a large amount of carbon and host highly diverse macrobenthic communities. They also play a key role in biogeochemistry at the sediment-water interface. The light requirements of seagrasses limit their development to shallow coastal areas where they are facing various natural and anthropogenic disturbances, which has induced a global loss of these ecosystems over the last decades. Nutrient enrichment of coastal waters, resulting from anthropogenic activities is one of the leading causes of this decline. Subpolar seagrass meadows present a strong seasonal dynamic, with a long winter when seagrasses rely on carbon reserves that they build up during the short growing season (limited to two to three months during summer time). Hence, it has been hypothesized that the effects of nutrient enrichment on seagrass ecosystem functioning depend on seasonal dynamics. In this study, we performed a series of mesocosm experiments over a month period to investigate the effects of the timing, duration and intensity of disturbance on macrofauna bioturbation, oxygen and nutrients porewater concentration profiles and benthic fluxes using three levels (including control) of realistic nutrient enrichments at the beginning (June) and at the end (August) of the growing season. In May, effects of intermediate level of nutrient enrichment were only visible on total oxygen uptake by the sediment at day 30 of disturbance while it affected oxygen and nutrients benthic fluxes at day 15 in August. The highest level of nutrient enrichment affected oxygen and nutrients benthic fluxes in May and August. Overall, our results highlight the importance of considering the time (period and duration) in the assessment of the functional consequences of disturbances.

How to cite: Pascal, L., Chaillou, G., Bernatchez, P., Nozais, C., and Archambault, P.: Influence of nutrients enrichment on ecosystem functioning in a subpolar seagrass meadow, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22581, https://doi.org/10.5194/egusphere-egu2020-22581, 2020

This abstract will not be presented.