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04/04/2002
Unsolved Southwest Florida Mysteries
Only one more day here on Marco Island before we start to head
back to New Jersey and the real world. Yesterday I headed out
on my predawn walk at 5:30 AM in order to enjoy the full moon
setting. It was perfectly clear, but I was disappointed by the fact
that, in March, the sun rises well before the moon sets - no big
orange moonset as I''ve witnessed in Februarys here. I did,
however, have a chance to be a Good Samaritan. I came upon a
very large horseshoe crab lying on its back high up on the beach
and posing a tempting morsel for the gulls. I flipped it over and,
sure enough, it was alive and immediately began plodding
toward the water. It was the first time I''ve listened to the "plop"
of a horseshoe crab as it travels. By the time I returned, heading
back home, the crab had made it to the edge of a tidal pool and
stood a good chance of surviving for another day. That horseshoe
must have spread the word about me because this morning I
found five horseshoes on their backs. One big one was thrashing
about trying to right itself with its tail; the others looked as
though they had expired. However, when I turned them over, all
five began their trek back to the water.
It''s a mystery to me why the horseshoe crab hasn''t evolved a
stronger tail so as to be able to flip itself over out of harm''s way.
Some weeks ago, I wrote about a fellow named Guth and how
his inflation theory may explain both the cause of and the early
history of our universe. I made the rash statement to the effect
that I could now die happily, thinking that at least someone
knows the very essence of our roots. My wife was rather
surprised and perhaps a bit concerned about that flippant remark.
On reflection, I''m not really ready to go yet. There are other
mysteries of a lesser scope for which I''d like to have the
answers. Such as the question about the horseshoe crab, which is
a relative of the long extinct trilobite and is more related to
scorpions and spiders than to other crabs. It is often termed a
living fossil, having existed essentially unchanged for over 300
million years.
There''s also a bird here called a skimmer by the locals that really
bugs me. I''ve seen these skimmers, which have rather long bills
for a gull-like bird, flying in formation with their mouths open
and their lower beaks skimming the water. Why do they do this
and how do they maintain their perfect height above the water to
allow them to skim for maybe 50-100 yards at a time? My
fisherman friends tell me the reason they do this is to "catch"
fish. One true fisherman insisted that the term "catch" be used
and not the term "fish", the latter being strictly a human activity
marked by exquisite craft and skill. They certainly didn''t explain
the exquisite control of the birds'' height so as to keep just that
inch or so of their beak in the water.
I''ve also noticed that a pelican will be flying along, periodically
diving into the water to catch and gulp down a fish. That
happens all the time. However, once in a while I''ll see the
pelican tailed very closely by a gull. The gull goes into the water
with the pelican just inches away and flies off immediately when
the pelican takes off. My knowledgeable friends tell me that the
gull is hoping for scraps of the pelican''s catch. This seems a
plausible explanation but my question is, if this is such a good
way to find a meal, why don''t more of the thousands of gulls
here take up the habit?
These little mysteries are small potatoes when it comes to the
really big mystery that is garnering a great deal of attention in
Southwest Florida. When we first arrived on Marco, the big
problem was the red tide, which stuck around here for just a
week or so. The red tide, with its killing of fish and it''s effects
on people with respiratory problems, is a frequent problem and
drew most of the media attention in February. But out in the
Gulf south of here, there was another phenomenon that has now
taken center stage - "black water".
This black water phenomenon was brought to the media''s
attention by fishermen who, back in January, noticed a large area
in the Gulf where the water was truly black. The black water
patch was not small. During the past few months its size seems
to have ranged from about 40 square miles to the size of Lake
Okeechobee, based on satellite photos. The fishermen reported
that the black water was like nothing they''ve ever seen and was
black with gelatinous blobs and filaments like spider webs
running through it. The black water was virtually devoid of fish
and dead bottom plants were seen floating on the surface. When
schools of fish encountered the black water they would begin
jumping and running rapidly and otherwise behave in a strange
manner.
The black water has now drifted into the Florida Keys and divers
in an area near Key West found dead fish, dying sponges and soft
coral on the bottom. Five loggerhead turtles were brought into
The Turtle Hospital in Marathon suffering from pneumonia or in
a coma-like state, apparently caused by black water. The
multimillion-dollar fishing industry in these parts really doesn''t
need any more crises like this. We mentioned previously
attempts to revitalize the sturgeon industry, with the Mote
Marine Laboratory as an important player in this effort.
Scientists at that laboratory are among those busy studying the
black water problem.
The origin of the black water is not likely to be settled quickly.
Proposals that it was caused by runoff from regions of heavy
rainfall have met with skepticism in some quarters. This proposal
suggested that sugar cane fields were a source of excess nitrogen.
One scientist has found ammonium compounds in samples of the
black water which, incidentally, is now greenish brown
according to one TV news report. Ammonium compounds are a
source of nitrogen (remember Fritz Haber?). Blooms of algae or
plankton are spurred by excesses of nitrogen or phosphorus and
could be the cause of the problem. One alternate proposal is that
the dying off of one algal bloom has fueled the growth of
another. Whatever the true origin of black water, it is generally
agreed that the Gulf is sick, quite aside from the black water, and
that action is needed.
What kind of action is a thorny question. Protection of the
environment is no easy job, as we''ve seen many times.
Sometimes, there''s the opposite concern - protection from the
environmentalists. One of the mysteries that has intrigued me in
the years we''ve been coming to Marco involves a vehicle that
runs up and down the beach with its headlights on in the early
morning hours. I''ve observed this vehicle, which has an
apparatus that churns up the sand and a screen or rug-like
contraption that then flattens the churned up sand. For years, I
thought the purpose was to clean the beach but couldn''t see any
obvious way it was doing that. The other evening we entertained
a couple that live here and the wife supplied the answer.
According to her, the purpose of the churning is to prevent
vegetation from seeding itself and propagating on the beach. She
said that the residents and condo/hotel owners are concerned
that, if the beach reverted to a wilder state, the environmentalists
would work to get it declared a bird sanctuary!
The other morning I came across a group of conches, not unusual
at all. But in this case there were many trails in the sand tracing
the paths of the critters. Some were a couple yards long. This
may not surprise you unless you''ve observed how painfully slow
these animals move. Several of the trails intersected other trails
and I wondered perhaps if an intersection marked a romantic
rendezvous. That evening we got together with some old hands
here and I asked if anyone knew about the mating habits of the
conch. My query prompted no informative response, only the
telling of a raunchy joke. Another mystery to carry over until
next year.
Well, as we bid farewell to Marco, I hope those horseshoe crabs
don''t count on me to come along and flip them over. From the
environmental standpoint, was I cheating the gulls or flies out of
a meal or was I helping to propagate the horseshoe species? I
noticed that the biggest one I flipped had made its way near the
water but had stopped to begin burrowing into the sand, perhaps
excavating a nest in which to deposit her eggs? I think I did the
right thing.
Allen F. Bortrum
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