There is a fresh water lake just next to my grandparents summer house (in Sweden). When I was a kid (25 years ago) I used to snorkel there for hours and hours.

This weekend I was back in the lake for the first time in ~5 years, and to my surprise there was Duck mussels [Anodonta anatina] every where. When I was a kid you could always find a few large one (10-15 cm) but now there was hundreds (+) of smaller (5-10cm) ones.

What I was wondering was if it possible to draw any conclusions about the conditions of the lake form these increasing numbers of mussels? It feels like it should be a good thing?

Thanks,
// Magnus;