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The Gulf of St. Lawrence

Food on the fly.
Photo: Biodôme de Montréal
Food on the fly.
  • Food on the fly.
  • Rocky coast.
  • Diver at work.
  • Thorny skate (Amblyraja radiata)
  • Gulf of St. Lawrence Ecosystem
  • Gulf of St. Lawrence Ecosystem
  • Common tern
  • Harlequin duck
  • Salvelinus fontinalis

The cold salt water of the Estuary and Gulf teems with life

A veritable inland sea, the St. Lawrence Estuary and Gulf extend from Tadoussac (at the mouth of the Saguenay River) all the way to the Atlantic. The fish-filled waters of this “Gulf of St. Lawrence Ecosystem” are teeming with plankton, a food source that attracts many whales.

The Biodôme's ecosystem, covering a total area of 1,620 m² and featuring a basin holding 2.5 million litres of “sea water” produced right here at the institution, reveals some of the shapes and colours hidden in these cold, salty waters.


The pathway runs alongside an underwater observatory, where you can spot hundreds of fish swimming in a basin filled with 2.5 million litres of “sea water”; it continues past a saltwater marsh frequented by teals; a rocky, wave-beaten shore whose bottom is strewn with a variety of invertebrates; and steep, rocky walls where seabirds nest. The granite rock recreates landscapes shaped by ice and millions of frosts and thaws.


The ambient air in the Gulf of St. Lawrence Ecoystem is kept at a much milder temperature than in the natural environment: in the summer, 17°C during the day and 15°C at night; and 15°C in winter. The relative humidity is much higher in the summer (60 to 70%) than in the winter (23 to 30%). The water temperature (10°C) and salinity (30 parts per thousand, or 30 grams of salt per litre of water) mimic the natural conditions of the Estuary. The water is treated continuously, through mechanical filtration (sand filters) followed by biological filtration and, finally, ozone purification.


Although the thin, poor soil that accumulates in the crevices of the rocks is not ideal, the common juniper and some coniferous trees still manage to find a foothold. The ecosystem also features a number of plants characteristic of transition areas between marine and land habitats.


The huge basin is home to hundreds of fish representing some 20 species (cod, striped bass, halibut, salmon, etc.). Invertebrates-starfish, sea anemones, sea cucumbers, limpets, sea urchins and crabs-are plentiful on the rocky shore. The winged world is represented by Kittewakes, common eiders and American green-winged teals, to name just a few.

Map of the ecosystem

Gulf of St. Lawrence map

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