> This is an old problem... How to cover the whole while doing justice to the
> composite parts... the Web model of ecosystems seems to me (as a Bumbling
> Amateur - and I should patent that description!) to suggest that there is a
> lot of interaction and interdependancy going on "out there". Is it possible
> to study a thing, be it a frog or a fish or a tree, in isolation from it's
> environment?
It's kinda like one of those catch 22 situations. If you study it out of
it's environment and you get a negative result (ie, exotic test species
has a negative impact on test organism) then it's a no go. If you get a
positive result, ie no impact, then it's a problem as further tests in
better conditions may show a negative impact. Also too, just because you
get a negative test result first up doesn't alway mean much either. It
depends on the situation. ie, Carp are tested for their impacts on blue
eyes, one large 30cm carp was placed in an aquarium. 10 2cm blue eyes
were added to the aquarium. All ten blue eyes were eaten by the carp
therefore carp are likely to be a predator of blue eyes. (assume they
are likely to co-exist in the wild). Artificial conditions would give an
incorrect result in this example. Carp are not typically pisciverous.
But almost any fish will eat another fish that is small enough to fit in
it's mouth especially if hungry and in the confines of an aquarium. You
just don't find fish in the stomachs of wild carp except perhaps some
pelagic type / surface dwelling larvae that got sucked in probably
incidentally. You would be surprised as aquarists as to how often you
see experimental setups just like the one I described, although not
neccessarily used to determine if an exotic fish would have an impact on
a native species but
for a whole range of other "scientific" pursuits!) Unfortunately, a
significant amount of scientific aquarium studies are conducted by non
aquarists (or more correctly beginning aquarists). And we all know how
reliable beginners are at keeping fish, let alone keeping them alive, let
alone doing good science with them! I'll get off my soap box now....
Tootles
Peter