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Gulf of St Larewnce – suffering from hypoxia

The Gulf is suffering from low-oxygen levels, hypoxia, threatening the future of the River. This silent killer was first identified in the mid-1980s. It is now confirmed that a large portion of the estuary is slowly but surely suffering from hypoxia and episodes of low temperature, causing starvation. The River is suffocating – dying 😥.

The Gulf of St Lawrence River is home to all sorts of marine life, as well as being  a central cultural and tourist hub for five of Canada’s provinces. Climate change is bringing warmer and oxygen-poor water into the gulf, with significant implications for bottom-dwelling fishes and crustaceans.

Low oxygen levels have led to reproductive problems in fish involving decreased size of reproductive organs, low egg counts and lack of spawning.

There are more than 146 dead zones in the world’s oceans where marine life cannot be supported due to depleted oxygen levels. Fish cannot live without oxygen and their very survival could be threatened if oxygen levels continue to decline. The ‘dead-zone’, in the St Lawrence, stretches from east the Saguenay River to east of the Baie Comeau, at depths over 275 metres (902 ft) – and growing year by year.


  • The river is being treated like a vast toilet. Municipal wastewater, fertilizer and manure used in nearby agricultural fields, and industrialization has placed large quantities of nitrates and phosphates into the water, creating added nutrients for the plankton, which allows them to multiply rapidly from spring through summer. As the abundant plankton dies and falls to the bottom of the river,it  decomposes and gradually consumes the ever-decreasing supply of oxygen.
  • PLUS: Climate change has also shifted the Gulf Stream and the Labrador Current at the Tail of the Grand Banks, where they meet.
  • If this trend continues, the deep waters of the River could, in the next fifty years, become anoxic (without oxygen) and massive suffication would occur. In short: the estuary would no longer be able to support any form of life, with the possible exception of some microorganisms.


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