My sincerest thanks to all who answered my request about using Ludox,
etc., for macrofauna sorting. I've been working with benthic samples for
many years and thought perhaps I was behind the times with respect to
our methods. From the comments forwarded to me it seems as though
there is still no easy way to deal with grab samples taken in sand and
gravel substrates. With one exception, there was a general feeling that
Ludox was not the answer for larger organisms, although a couple of
people have used it to retrieve smaller worms and crustaceans. It seems
that the most satisfactory solution was to run water into the sample and let
the lighter materials float onto a fine mesh screen. A quick post-float
examination is then used to retrieve larger organisms. We have done
this with dredge samples, but have not used the technique with
quantitative samples. Still, it seems that it might be as accurate as long
times spent picking. One person suggested looking into industrial
separation technologies, which I think we will do, but most probably those
methods will wind up being expensive, or as in the case of
trichloroethylene or carbon tetrachloride, have rather high costs to the
health of the sample processors.
All the best, Les.
Les Watling
Professor of Oceanography and
Pew Fellow in Marine Conservation
Darling Marine Center
University of Maine
Walpole, ME 04573
Phone 207-563-3146 x248
Fax 207-563-3119
<watling at maine.edu>
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