After a few days exploring the marine environment around Les Escoumins we are now headed for the Saguenay Fjord. Carved by glaciers during the last ice age, the Saguenay Fjord is a thin U-shaped valley, 105 km long and on average only 1.6 km wide. Cliffs tower above the surface of its waters, reaching 412 m at their highest point, Cap Trinité. They continue to plunge into depths of over 275 m.
High cliffs at the edge of the Saguenay Fjord. Credit: Ellen Fanning/Huntsman Marine
Skipper Carl Tremblay has quizzed us about our diving experience to make sure we are qualified enough to safely dive the fjord. All divers must have experience of night diving and diving in currents. But why night diving when we are here in the daytime? We are ready for our first dive, and it is time to find out!
The team onboard the Accès Plongee Saguenay boat with skipper and dive expert Carl Tremblay.
Charlie, Claire, Andrea and Jo prepare to dive. Credit: Ellen Fanning/Huntsman Marine
Explos-Nature diver Julian, my buddy for today, and I are ready to dive. We step off the platform at the back of the boat and swim rapidly to the wall to avoid being swept away by the current. We check in with each other and start to descend. There are two distinct water layers within the fjord. As we start to sink, we are first passing through the upper freshwater layer. At this time of year, it is pleasantly warm, it can reach up to 20°C in summer, but in winter it freezes. Mussels cover the wall. Only freshwater species can live here, salinities range between 5 and 26 ppt. I look up towards the surface. The light is an eerie reddish-orange colour. This freshwater comes from Lake Saint-Jean and the tannins and iron from the forests that surround the lake make it a tea-like colour.
The brown surface water blocks out light so by the time we reach 15 m it is almost completely dark. I am very glad of my large video lights. I check in with Julian and we continue to descend. The water starts to shimmer and become hazy, it’s hard to see Julian even though he is right next to me. The top fresh layer and the deeper marine waters are starting to mix, causing this effect.
We are now entering the seawater that forms most of the fjord. This layer is fully marine, varying in salinity from 26 to 31 ppt. It is also much colder than the surface waters for much of the year, typically between 0 and 4°C, although recently it has been warming and today it is around 6°C.
The unique environments found in fjords mean that you often find deep-sea organisms much shallower than they would normally be present. So, sampling here is a great opportunity for us to get specimens of deeper water species for our project. We reach our target depth and I start to sample. The rock walls are covered with life: bright red sea strawberry soft corals, basket stars with tangled arms, and most exciting for me, many sponges. Although I have to admit the iridescent bobtail squid are rather more fun to watch!
Sea strawberry soft corals and basket stars on the wall at Cap Trinité. Jo is using bright lights to take this photo, or this would be pitch black. Credit: Jo Porter
This sea slug species was common, here you can see a group and their egg masses to the left. Credit: Claire Goodwin/Huntsman Marine
Bobtail squid were frequent in the Saguenay Fjord. Credit: Claire Goodwin/Huntsman Marine