Henk, Peter, Peggy, Avril,

Neritina (Vitta) usnea is abundant in Mobile Bay (Alabama) and can tolerate
low salinity. On natural marshy shorelines, which are becoming increasingly
limited, the dead shells form windrows; the shells have a delightfully broad
variation of color pattern but the pattern shown in Avril's photo is the
most common. As to barnacles, I have seen some growing at the head of the
bay in water reported to have only about 3 parts per thousand salinity
(about 1/10 that of seawater).

A few estuarine species can live in freshwater without difficulty as adults
but cannot maintain populations there because their reproduction requires at
least brackish salinity. In the same area, these include the bay clam Rangia
cuneata, and I would guess probably also the Carolina marsh clam, Polymesoda
caroliniana. None of these are known to live in ordinary seawater. The
common oyster Crassostrea virginica has just the opposite preference: It
normally thrives in brackish water, but when predators are excluded, it does
even better in fully marine salinity.

Andrew K. Rindsberg
Geological Survey of Alabama

-----Original Message-----
From: Conchologists of America List [mailto:[log in to unmask]] On
Behalf Of mienis
Sent: Monday, August 09, 2004 10:42 PM
To: [log in to unmask]
Subject: Re: Freshwater barnacle


Seems to me Vitta usnea (Roeding, 1798), better known as Vitta reclivata
(Say), might occur in estuaries. Henk K. Mienis

----- Original Message -----
From: "Avril" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, August 10, 2004 4:22 AM
Subject: Freshwater barnacle


> Hello Conchlers,
>
> I have a gentleman looking for help on identifying a freshwater snail
> with barnacles living on it's shell.  The snail was purchased in a New
> York pet store and no one can identify the snail nor the barnacles.
>
> The Mystery Page is located at:
> http://www.manandmollusc.net/Mystery_shell_pages/peter-mystery.html
> Peter can be reached at:  mailto:[log in to unmask]
> All list replies will be forwarded on to Peter as well as placed on to
> the page.
>
> Thank you in advance for any and all help.
>
> All the very best,
> Avril Bourquin
> PO Box 366
> Invermere, BC
> Canada, V0A 1K0
>
> Phone/Fax:  (250) 342-7224
> Cell Phone:  (250) 341-5189
> Email: [log in to unmask] <mailto:[log in to unmask]>
> URL:   http://www.manandmolllusc.net
>
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