"Bob Weinberger" wrote in message
news:Shhli.7806$475.4835@trndny04...

"Dave LaCourse" wrote in message
...
This was posted on a fly fishing forum in both NH and ME:

+++++++++++++++++++++++++++++++++++++++++++++

Fly Fishing Guide Lawton Weber discovered the invasive algae Didymo on
the upper Connecticut River on June 25, 2007.
snip
George Adams: You fish the CT up north, I believe. Have you heard
anything about this? If it's up there, it will soon be throughout NE.
Stream cancer without a cure...... scarey. This could endanger the
Deerfield, Westfield, and Farmington to name a few rivers. And Maine
is just over the horizon from the upper CT. I understand that there
are rivers out west that are also infected, as well as some in Quebec.

Dave
Although , for reasons no one has been able to determine, Didymo has
recently started acting like an invasive species and forming large
"blooms", it is native to North America (and Northern Europe). So it is,
likely already endemic in most streams in New England, but the conditions
that cause it to become super aggressive may have not yet expressed
themselves in those other streams. In New Zealand and Australia it is not
native, so it is truly an invasive species there.
I have a theory as to why it may have recently started to become a problem
in its native area, and, if the theory is correct, is ample reason to
carefully clean fishing equipment before traveling from one watershed to
another, even if Didymo is endemic in both watersheds. My theory:
Didymo which was introduced to New Zealand (first described there in
2004), from North America or Northern Europe, thrived there and perhaps
slightly mutated to a very aggressive form. This more aggressive form may
then have been brought back to North America on fishing equipment or
boats, etc.

On the face of it, there is nothing obviously and fatally wrong with that
theory (well, o.k., boats from New Zealand to the Connecticut River is more
than just a bit shaky, but otherwise.....). On the other hand, aside from
mere plausibility there is nothing to support it either. Certainly, in an
era in which regular monthly.....or even weekly....commutes between ANY two
major cities in the world (like Sydney or Auckland and New York or
Washington D.C. for instance) is a near certainty, and in which fishing in
fabled streams within easy reach of those cities' airports is a common
enough avocation among those who can afford, or whose work compels, such
travel, the scenario you propose COULD account for the facts. But why posit
a tenuous chain of exportation, mutation, and re-importation when a mutation
at home would cover the ground just as well? Or, for that matter, why rely
on mutation at all when any number of well-understood (and, in various
similar situations, well-documented) environmental factors could easily
account for the sudden problematic burgeoning of a particular heretofore
benign organism?

Wolfgang