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02/29/2000
Microbes, Vultures and Conches
I just returned from my usual morning 4-6 mile walk on the
beach at Marco Island in Florida and picked up my latest issue of
the American Chemical Society''s publication "Chemistry."
After my walk, I was caught up in the influence of microbes on
the environment and an item in Chemistry dealing with
beneficial microbes which live in lake and stream bottoms.
These microbes apparently love to dine on methyl tertiary butyl
ether (MTBE) and just plain tertiary butyl alcohol (TBA). I
don''t expect you to be familiar with either MTBE or TBA and I
certainly would not be myself, except for the recent furor in the
media over MTBE in particular. For the past few years, MTBE
has been mandated as an additive to gasoline which lessens
pollution and results in cleaner air. TBA is another gasoline
additive. Now it seems that MTBE is a potential human
carcinogen that is making its way into our ground water supplies.
The MTBE, according to the article, evaporates into the air when
you fill your gas tank. It then dissolves in rain and ends up in the
lakes and streams. Gasoline spills may permit MTBE to take a
more direct route into our water supplies. At least in the lakes
and streams, however, these "good" microbes degrade the MTBE
and TBA into nontoxic products. The whole affair of the
legislated addition to and now removal of MTBE from our
gasoline illustrates again the complex interactions that can result
from fiddling with our environment.
But back to my walk this morning. I''ve been walking the beach
here on Marco Island for over 4 years now and today saw
something I''d never seen before. Lined up on two areas of the
beach were hundreds, maybe thousands of Florida conch shells.
I hadn''t seen more than maybe tens of these shells before and
they were typically scattered over a wide portion of the beach.
Furthermore, today''s shells were not dead but were moving,
propelled by the very much alive conches inside. Virtually all
the conches were associated with circular holes in the sand about
1-2 inches deep, out of which they must have emerged. One
fellow beach-walker said he had been coming to Marco for 20
years and had never seen anything like this. I was so taken with
the conches that I forgot I was walking on a sandbar without a
dry path to the main beach. As a result, I had to retrace my steps,
adding an extra one-half to three-quarters miles to my walk.
Today, my wife and I also hosted some relatives from
Pennsylvania and we took them on a tour of the island, which has
some very upscale houses in beautifully landscaped
neighborhoods. At one point we were all shocked by another
sight which I had never seen before in my 72 years. In this one
neighborhood, there were hundreds of large black birds flying
around and roosting on the roofs of these fancy homes. At first,
we all thought they were very large crows but when some flew
near our car we realized that they had rather evil-looking faces.
Well, what should appear in the local paper today but an article
about homeowners in the Marco area under siege by hordes of
vultures! The residents found it impossible to go outside and
enjoy any outdoor activities. Apparently, vulture droppings are
considerably more of a problem than those of the passing
seagulls. Why all the vultures? They have come to feast on the
piles of dead fish washed up on the banks of the river and inland
waterways so plentiful in this region bordering the Everglades.
Why the dead fish? Microbes, in the form of the "red tide," are a
likely answer, according to the newspaper article. I have to rely
on my feeble memory (no computer or Web access down here),
but I believe that the red tide is caused by proliferation of some
kind of algae or other organism(s) that periodically foul the
warm waters off the Florida coast. My own hypothesis is that the
red tide is also responsible for the conch-beaching I observed this
morning.
So, here we have an example of "bad" microbes resulting in
profound local environmental effects. Obviously, the red tide
effects are restricted to this relatively limited geographical area.
The MTBE-eating "good" organisms, if they can be widely
deployed, may have a much wider and beneficial impact if
MTBE contamination is as widespread as some media reports
indicate.
This environmental stuff is really tricky. Some day I may get up
enough courage to try to write about global warming!
Allen F. Bortrum
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