Before answering the question, some context is necessary.
In early July, we were informed of the presence of snails at Black Lake, most likely Chinese Mystery Snails. To find out for sure, we called on a biologist from the MRC d’Argenteuil to ensure that they were indeed Chinese Mystery Snails, an exotic and invasive mollusc.
This confirmation obtained, checks in the three other lakes of Dunany revealed their presence there.
They have been recorded in several sites, near the banks where the water is shallow and calm. Testimonies confirm that they have been in our lakes for several decades. Moreover, during the annual general meeting on July 28, almost all the members present said they had always seen them in their lake.
So, why are these snails not very invasive in our environment?
Chinese Mystery Snails develop where the water is calm and shallow. But, as the average depth of our lakes ranges from 5 to 10 meters, the surface area of our lakes available for these snails is very limited.
In addition, pieces of shells observed in certain places show that they are the joy of several predators such as herons and otters who delight in them.
In short, our lakes seem to have adapted to the presence of these snails so that they do not constitute a problem at this time, as it can often be the case in the numerous shallow lakes (average of less than 2 meters) created by the damning of rivers or creeks.
If you read my last report on the state of our lakes, you know that they are in good health. You may recall that the Boyd Lake results were intriguing. However, we have received the results of the June 2024 sampling – the first of three – where all the lakes, including Boyd, display phosphorus levels which place them comfortably in the oligotrophic (very good) category.
Nevertheless, the Association will ensure constant vigilance to ensure that the situation remains stable.
These snails are now found in hundreds lakes in Quebec, as elsewhere in Canada. This is hardly surprising given that they were imported in large quantities as very effective aquarium cleaners. Then, in the 40s, they were deliberately discharged in shallow Lake Erie to provide food for fish. It was enough to contaminate the St. Lawrence.
Your questions and comments are always welcome.
Thank you so much Jacques for your continuous information on our beloved lakes. I have noticed these snails since we have been residents of Dunany! I am grateful for the information you provide! You are the best!
I remember them being in the lake over 50 years ago! Always wondered if a brime could be made, to make them edible? I enjoy being an adventurous cook 😄
Your comment is most appreciated John. It gives me fuel for a future article. Cheers.
Jacques,
Thank you for this excellent explanation and background on the Chinese Mystery Snail.
Like so many other Dunany Lakers we can report seeing these snails for a number of decades without knowing what they were called and how they got here.
We very much appreciate the effort you put into this report and grateful for the information it provides.
John
Thanks so much for this info!
Possibly Jean,but we looked hard and could not fin any.
Are there other types of snails in our lakes? I have never seen anything as big as shown in the photo.
This is very interesting.
Yes, I have seen them for decades, and hadn’t given them much thought. Thank you, once again, Jacques, for helping us to understand more about our community.