Snails below the dam at Oxford Mills

[Fred Schueler]

Everyone,

One of the most striking things about this fall's Mudpuppy Nights has
been the pale deposit of shells and snails below the ledge below the
central spillway. These comprise a variety of species, mixed with the
remains of predated Crayfish.

Last night I took a fine-mesh net, and scooped up about half the volume
of this deposit, and, as shown in the attached photo, it has a lot of
Helisoma shells, both H. trivolvus, and H. campanulatum, with both
shells and living Physa. and many of the little snails that I don't
recognize to species. There are a couple of Lymnaea stagnalis shells,
and this week a living Bulimnea megasoma (just using the old names from
Clarke, 1981, here).

The most exciting thing is the big dark high-spired Lymnaeid, both
shells & alive, which match Clarke's Stagnicola reflexa, which he says
"Occurs among vegetation in a variety of perennial-water and vernal
habitats, namely lakes, ponds, sheltered areas of streams, swamps, and
ditches. The usual substrate is mud. ...considered by some authors as a
morphological variant of S. elodes."

We've previously found a few shells like this in Clarke's "variety of
perennial-water and vernal habitats," most recently this spring in
Kemptville Creek at County Road 20 when Aleta was looking for Leopard
Frog egg masses.

Finding them common in the material swept over the dam, from the
upstream creek which goes anoxic in many winters, leads one to wonder
what adaptations to anoxia they may have, and how this may relate to the
adaptations the related Stagnicola elodes (Ladislavella elodes) to
habitats of temporary water.

I'm going to keep these 'reflexa' alive and see how they do.

fred
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Frederick W. Schueler & Aleta Karstad
Fragile Inheritance Natural History - https://fragileinheritance.ca/
6 St-Lawrence Street Bishops Mills, RR#2 Oxford Station, Ontario K0G 1T0
on the Smiths Falls Limestone Plain 44.87156° N 75.70095° W
(613)258-3107 <bckcdb at istar.ca>
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