I have been noticing shells of what I believe is the freshwater pearl mussel, scientific name Margaritifera margaritifera, scattered about the shore of my pond. The culprit is river otters that come up from my stream (about 1000 feet away) and dive for them and sit on the shore and have a feast. I have been reading these mussels are now declining in population.

I have lots of these in the pond or I did before I found lots of shells on the shore. What do they say about my water? Are they, like the bryozoans I have, a sign of good water quality? I doubt the otters will wipe them out as I have seen shells every spring but not as many as this year.

Maybe these are not Margaritifera but an impersonator which I have mis identified but it has me curious as to what populations of invertebrates are common in northern ponds and which populations are good and which populations I should be concerned about.

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