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On 11/10/2011 7:16 AM, Dusan Soudek wrote:
> Aquatic "snails?" Do any species utilize anadromous fish species to
> take their larvae upstream, thus establishing and maintaining
> populations in headwater lakes and streams.
* not as far as I know. Snails are born alive or hatched from eggs in
jelly, and don't have a specialized dispersal phase. They're thought to
spread by sticking to the feet or plumage of Birds and then dropping
off. Often there are striking instances of water bodies which lack
aquatic snails. I'm copying this to Rob Dillon, who runs the Freshwater
Gastropods of North America - http://fwgna.blogspot.com/ - and would
know if any such early-life dispersal adaptations are known.
> This is quite common in the
> "snails'" cousins, the bivalve molluscs.
> I remember reading about a freshwater mussel species becoming extinct in
> N.B.'s Petitcodiac River, after the tidal dam/causeway in Moncton
> destroyed the salmon run there. I do wonder whether this species is back
> now that the dam is open again.
* we drove past there this summer, and regretted not having the time or
low water that would be needed to search, but this was an isolated
population (nearest was in New Hampshire - none in Maine) - of a
short-lived species - Alasmidonta heterodon - see
http://en.wikipedia.org/wiki/Dwarf_wedgemussel
> I have never come across a good review of this topic. The larvae of
> relatively immobile invertebrates literally hitching rides on highly
> mobile searun fish to travel hundreds of miles upstream...
* the species that has made big range expansion after coastal dams have
been removed is Anodonta implicata, the Alewife Floater, which has the
host suggested by its English name, and also uses shad as a host, and
which has gone scores or hundreds of km upstream when dams have been
removed. It used to get (rarely) as far upstream as Ottawa before the
Seaway.
fred.
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Frederick W. Schueler & Aleta Karstad
Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
Daily Paintings - http://karstaddailypaintings.blogspot.com/
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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