[NatureNS] lots of empty FW Mussel shells- why?

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From: nancy dowd <nancypdowd@gmail.com>
Date: Fri, 16 May 2014 17:33:01 -0300
References: <7C9600E8-E450-4CE6-8D23-0FC48D217D19@gmail.com> <CAMYYejTpzdo-R8ZD6Fim5+EQFD37+FEyeTpAAZ_x-iPf6+HgLQ@mail.gmail.com> <53766E05.3080104@istar.ca>
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"None" means I saw no living specimens. Sorry for not being clear.

Nancy
On 2014-05-16, 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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