A few questions about diving the Saint Lawrence River

[BringBackPluto]

Hi, I'm new to the site, but not to diving. Sorry if this topic has already been posted, but I am a PhD student studying zebra mussel populations in the SLR (mostly between Montreal and Quebec City). So my question is:

For those that have gone diving in the SLR, could you tell me where you were and what the bottom was like? (Mussels hate mud, love rocks). Alternatively, can anyone point me in the direction of a sediment map of the SLR?

I'd also appreciate any tips you might have.

Thanks so much!
-BBP

 

[Ayisha]

We used to see tonnes of zebra mussels, an invasive species, in the shape of a wreck years ago, which was awesome for the visibility. In the last 8 years or so, visibility has been steadily decreasing from well over 100 feet and crystal clear at some sites 11 years ago to sometimes 5 or 10 feet and extremely silty now. There are fewer and fewer zebra mussels on the wrecks. The mostly dead mussels tend to be opened up and strewn about the silty muddy bottom. We didn't see any or many gobies 11 years ago, but now you see tonnes of gobies, which are apparently eating the zebra mussels.

Something's going on in the St Lawrence that is severely impacting the visibility. Some say that it's the other invasive species, the gobies, that are decimating the mussels and the visibility. Some say that it's also the new development and run-off in the area creating the ever-increasing siltiness. Each year I can't believe that it could be worse than the year before, but it keeps happening. I'm going for the July long weekend, and I'll hope for the best.

I've done almost all of the wrecks/sites in the SLR - Muscallonge, Gaskin, Kinghorn, Lillie Parsons, Daryaw, barge drift, walls, Keystorm, America, Vickery... Even the Lillie drift that is surrounded by rocks is depleted of mussels. Zebra mussels love wood wrecks too, but they're few and far between.

It's good that you're studying this because the question of what's going on in the SLR gets asked all the time and hopefully we can get some scientific answers. Thanks.

 

[DandyDon]

This Round Gobi from Asia is becoming a major player in the system there it seems: reducing invasive mussels, eating native fish eggs, food for native fish, birds, and even the threatened water snake making a comeback, conveyor of parasites, diseases, and PCBs higher in the food chain.

 

[Ayisha]

That is very sad, DandyDon. I think I've seen 2 types of gobies in the SLR, one black, one grey IIRC. I posted what they look like on SB before right after seeing them, but IIRC, one type was round and big, the other skinny and long. I'll see them again next weekend I'm sure, and I hope to be pleasantly surprised with the viz... Last year was awful viz. It can't get any worse, can it?

 

[BringBackPluto]

Thanks so much for the great responses! We got in today for a test run near Cap-Rouge, and will probably do another couple of dives tomorrow.

Your responses are great because my perception was that the only thing stopping zebra mussels was their also-invasive competitor, the quagga mussel. I have heard a little bit about these gobies before posting on SB, but it looks like I should do more research!

Again, thanks so much, and of course, any more stories or tips are welcome