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Index of Subjects The empty shells are distributed as shown in the pictures: In the water all over the bottom with the convex exterior side facing up (I hope you could view the pictures?- I will send you them if not). I flipped a few over with a stick just to see if these were whole mussels or half shells. Virtually all of them are shiny side down somewhat pressed into the sand. To me it looks like the wave action has brought the shells into shallow water where they have lodged. They are so evenly scattered. Maybe from other parts of the lake? There are no shells on the shoreline which has been submerged until last week except a few wedged into rock crevices presumably by the waves (?) as the third pic shows. None piled up in the woods or rocks that were above high water levels either. So the distribution does not seem to point to a particular predator. Raccoons do occasionally leave small shell piles on the beach in the summer though. Nancy On 2014-05-16, at 5:26 PM, Dusan Soudek <soudekd@ns.sympatico.ca> wrote: > I always thought that the major predator of freshwater mussels, and the creator of miniature shell middens all over the shorelines of our lakes and rivers with sandy substrates, was the raccoon.. Can you tell which mammal species was the predator from the distribution of empty shells? > Dusan Soudek > > > On May 16, 2014 at 4:59 PM Fred Schueler <bckcdb@istar.ca> wrote: > > > > > > On 5/16/2014 1:06 PM, David McCorquodale wrote: > > > Muskrats are important predators of freshwater mussels in eastern North > > > America, including NS. Often they pile shells in middens. > > > > > > In Blacketts Lake and Pottle Lake in CBRM piles of shells of several > > > species of freshwater mussels, including the Yellow Lamp Mussel, are > > > obvious. > > > > * these URLs just took me to a general flckr site, not to the individual > > photos. > > > > Muskrats and Beavers can process astonishing numbers of mussels, and > > often leave the shells quite undamaged - and nonhuman mammals, with weak > > connections of cultural memory can "discover" a food source and use it > > to depletion for one generation with the descendents never learning > > about it, giving the prey time to build up to high density. > > > > Freezing or anoxia can kill mussels, though they'd die buried in the > > substrate, and wouldn't be expected to be on the beach this early - also > > low water levels can cause mass mortality. Without being able to see the > > pictures, I can't say what species these are, but if they're Anodonta or > > Pyganodon "Floaters" the light-weight shells would be more likely to > > work loose from the substrate and blow onto a lee shore. > > > > fred. > > ============================================== > > > > > > > > On Fri, May 16, 2014 at 1:35 PM, nancy dowd <nancypdowd@gmail.com > > > <mailto:nancypdowd@gmail.com>> wrote: > > > > > > Water levels have dropped just enough on L Torment to show about 6" > > > of beach in places now but the shore has been completely submerged > > > since last October. The number of mussel shells seen in these > > > pictures is unusual: > > > > > > At the end of the path they are visible as far as you can see out > > > into the water: > > > https://www.flickr.com/photos/92981528@N08/14196083311/ > > > > > > And it is this way the whole way along the shore. Another view 40' > > > along the submerged beach: > > > https://www.flickr.com/photos/92981528@N08/14012727849/ > > > > > > This side of the lake has the prevailing onshore winds and waves and > > > the shells are starting to collect in the exposed pockets: > > > https://www.flickr.com/photos/92981528@N08/14199406975/ > > > > > > Why so many empty mussel shells? Would the winter somehow have been > > > hard on them- ice or cold or oxygen levels? Doesn't look like > > > predation to me- too many shells. This is the first year I have ever > > > seen anything like this. > > > > > > Any ideas? > > > > > > Nancy > > > > > > > > > > > > > > > -- > > ------------------------------------------------------------ > > Frederick W. Schueler & Aleta Karstad > > Daily Paintings - http://karstaddailypaintings.blogspot.com/ > > Vulnerable Watersheds - http://vulnerablewaters.blogspot.ca/ > > study our books - http://pinicola.ca/books/index.htm > > RR#2 Bishops Mills, Ontario, Canada K0G 1T0 > > on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W > > (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/ > > ------------------------------------------------------------
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