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Fluvial inputs

Increased fluvial inputs of organic carbon and nutrients associated with human activities can lead to eutrophication in estuaries and coastal areas. This eutrophication can result in the proliferation of toxic or harmful algae and the development of hypoxic and acidified areas that threaten the health of the St. Lawrence River. The participants have resolved to evaluate and gain a better understanding of the contribution of fluvial inputs on hypoxia, acidification, and the appearance of toxic algae in the estuary.

Projects 2016 - 2021

Understanding how organic matter contributes to hypoxia and acidification in the St. Lawrence Estuary

The waterways that empty into the St. Lawrence Estuary bring sediments and organic matter to the deep waters. The primary production (particularly the production of plankton in aquatic environments) usually generates organic matter that reaches the deep waters. In this area, this matter degrades and we observe a reduction of the oxygen concentration and acidification of the water. Conditions in this zone can be hard  for marine life. 

During this project, our researchersseek to better understand how organic matter contributes to hypoxia (lack of oxygen) and acidification in the deep waters of the St. Lawrence Estuary. They try to specify the source of this dissolved and particulate organic matter and recommend, if possible, its reduction at the source.

Data collected within this project allow the improvement of the biogeochemical 3D model.  Two scientific articles arise from this project.

Hudon C., Gagnon P., Rondeau M., Hébert S., Gilbert D., Hill B., Patoine M., Starr M. Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada). Biogeochemistry, 135 (3) (2017), 251-276 

Lebeuf, M., Maltais D., Larouche P., Lavoie D., Lefaivre D., Starr M. et Scarratt M. 2019, Recent distribution, inventories and temporal trends of suspended particulate matter in the St. Lawrence Estuary, Canada. Regional Studies in Marine Science, Volume 29