Sorry I missed the ruckous- I've been too busy grading intro biology lab
reports (Yeech!) to get around to checking my mail.
>I'd be interested to know if people believe a body of water like the
>Potomac is enhanced or 'bettered' by the introduction of species that are
>not native to it. If the density and/or diversity is increased with more
>'desirable' species should this be noted as an improvement? Or, would all
>changes from original compositions be negative due to human 'interference'
>in a natural habitat? I think most list members would agree that the
>introduction of a non-native
>species would not constitute an improvement, but how about a NANF
>being introduced to a new environment within North America?
Think about this one- carp were originally introduced into NA to be the
ultimate food and game fish, and to keep all these silly Europeans satisfied
with fish like what they were used to eating. What humans perceive as
'desirable' does not necessarily equate to ecologically sound. There are way
too many other examples to list... walleye and channel cats in the Columbia
Basin, flatheads in the Colorado and southeastern Atlantic Coast drainages,
brook char all through the Rockies, Gambusia across the known universe, etc.
'Species diversity' isn't an excuse for adding exotics- in actuality,
there's a huge body of ecological studies that suggest that species
diversity is highest under intermediate levels of disturbance. This is not
an excuse to go out logging trees to increase 'diversity.' What you wind up
with then is a lot of 'weedy' taxa that are good colonizers, and a very few
things that are specialists. Sound familiar? Hey, Pimephales weren't ALWAYS
as common as they are now...
A lot of fundamental ecology is common-sense when it comes right down to it-
don't underestimate yourself because you don't have a PhD. The problem is
that, especially in complex systems, we really don't know all that much
about the intricate interactions between taxa and ecosystem components.
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