At the end of last year, someone mentioned to me in passing that there is a lake in MN that has freshwater coral. This statement amazed me, as coral need very specific conditions to grow.
I did find one mention of this on this forum, but no one else has said anything about it:
Has anyone seen this freshwater coral, does it exist or is this just a myth?
My family has had a lake home on Eagle for, well, a very long time. My great grandparents homesteaded on Eagle and owned about a quarter of the lakeshore. Now that homestead is divided up and many of my family members still have cabins on the lake.
I, too, have always heard stories about the coral from my grandfather and my father. Neither of them have ever seen it but only knew about it.
Since I have started diving I have made quite a few dives in Eagle in very specific places. And... Yes, it does exist... by the TON! There are many places I have found it but there is a catch. It is all dead; very dead.
The lake has changed dramatically over the years especially the clarity. Much of the coral is in 30 feet or more (the lake tops out at about 46 feet) and I just don't think the water is clear enough anymore.
When my dad was a kid he said the lake was like crystal. He would spot a clam on the bottom in 20 feet and freedive down to it. Well, not anymore. On a good day of diving you may have 8 to 10 feet of vis or so.
It would have been absolutely amazing to see all of the coral in it's prime. I highly doubt there is any alive anymore as I have seen a lot and all of it has been dead. It is still very unique and cool to see.
BioDiver
I would love to see this, and will dive there this year. Would you share the approx. location of some of the fresh water coral. Feel free to pm me if you wish to keep this information private.
While I would like to share I am also hesitant; since even though it is dead I feel it should still be left undisturbed. It is so unique and a part of the history of a lake I love. I know most of us feel like I do too, it just takes a few to ruin the bunch.
Luckily the best spots are hard to find since they are small areas off-shore. You need a boat and sonar or you will never find the humps. Even then, I miss on occasion. You are looking for rocks. Anywhere I have found large rocks I have found the coral. Use a lake map, boat, sonar and you will find it.
When I am around there I would be glad to take people to see. I don't get to vacation as much as I would like so it seems I don't get around "The Lake" as much as I would like. Perhaps I can post on here when I will be around and can arrange something with those who are interested.
Are you sure this was actually coral? Any links to online pictures or scientific articles?
I have heard that the "deposits" are of unknown origin, but are not coral.
Sad to see any lake deteriorate, much less one that nice.
It's not actually coral. Instead it is a type of algae that grows on the rocks. Sometimes they are referred to as stromatalytes.
It does make the rocks look somewhat like coral heads, but there are no polyps.
I have found the same types of growth in a couple other lakes, including Pebble in Fergus Falls.
One place that I found a ridge was straight out from the boat landing at the park at about 34 feet deep. It's a long swim though, so the boat and sonar idea is a good one.
Ballfrog's info is correct. The algae is usually yellow/white/orange in color. I've got some pictures at the shop, check them out the next time you're in.