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Dispersal in Pond Snails: Potential Role of Waterfowl
Boag, DA
Canadian Journal of Zoology CJZOAG Vol. 64, No. 4, p 904-909,
April 1986. 3 fig, 3 tab, 27 ref. Natural Sciences and Engineering
Research Council Grant 2010.
Young pond snails of three species (Lymnaea stagnalis, Stagnicola
elodes, and Helisoma trivolis) were allowed free access to
waterfowl feathers floating on the surface of shallow containers.
Snails adhering to the feathers were subjected to simulated flight
conditions by placing them in an air stream. The size of these
snails, the length of time they adhered to the feathers while in
the air stream , and their survivability for various lengths of
time under these conditions were recorded. Those snails that
adhered to the feathers were mainly small individuals (<2.5 mm
long in all three species). The proportion that remained clinging
to the feathers declined sharply with time: after 15 min of
exposure only 6% of L. stagnalis, 18% of S. elodes, and 15% of H.
trivolvis remained. Survivability also declined with exposure to
the simulated flight conditions: after 15 min only 50% of L.
stagnalis, 23% of S. elodes, and 15% of H. trivolis were still
alive. Larger individuals tended to survive better than smaller
ones for any given exposure time, but they also tended to fall off
the feathers sooner than smaller ones: no snail more than 3 mm
long was recorded adhering to the feathers for more than 4 min
under the test conditions of simulated flight (air speed of 41
km/h). The data recorded suggest that despite a low proportion of
the snail population adhering to the feathers (1% of those
available at any given time) and the relatively high rates of
loss, either by falling off the feathers or dying in situ after
adhering, the probability of successful dispersal for distances up
to 10 km remains high (a mallard flying for 15 min at 41 km/h was
deemed capable of carrying at least three surviving individuals of
any of the species tested over a distance of about 10 km). Of the
three species tested, S. elodes had the greatest probability of
successful dispersal, which may explain its almost ubiquitous
distribution in the water bodies of central Alberta. (Author 's
abstract)
 Descriptors: Snails | Ponds | Waterfowl | Ecosystems | Alberta | Birds | Aquatic
populations | Survival
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