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While on a boat relaxing with friends recently, somehow the subject of those
popular mylar party balloons came up. I explained my position that these
nearly non-biodegradable versions of the traditional latex balloons often
find their way over the ocean by the time they leak enough helium to fall
back to earth. Floating on the ocean surface, they are often mistaken as
jellyfish by the magnificent Ocean Sunfish and also by our endangered sea
turtles. The diet of these ocean creatures consists almost entirely of
jellyfish and their close relatives. Once ingested, the balloons clog the
sunfish and turtle digestive tracks, which often results in death. Anyone
with any environmental sensitivity should boycott mylar party balloons.
The conversation then shifted to the importance of jellyfish. I explained
that these primitive animals occupy an important place in the ocean
ecosystem. I explained how they eat large quantities of fish, invertebrates
and plankton, recycling nutrients and otherwise occupying an important niche
in the marine food web.
True jellyfish are members of the Cnidarians. These and several related
phyla, the members of which, like the Portuguese Man-o-War and the familiar
sea walnut that phosphoresces in boat wakes on the bay, are all often
commonly called jellyfish. Their evolution is relatively obscure, since they
are mostly water with no hard body parts to leave a good fossil record. But
their primitive nature is inferred from their simplicity and their
similarity to sea anemones, corals and other ancient lineages. They are
little more that a pulsating bell, a digestive tract, and reproductive
organs. Strangely, however, one group of the jellyfish-like creatures, the
tropical, and often deadly, box jellies, possesses fully functional eyes.
Clearly there is much about these beautiful creatures that we have yet to
unravel.
One more aspect of the important role that jellyfish play in marine
ecosystems has recently been discovered. In a recent issue of the journal
Nature, researchers describe how jellyfish mix and stir the ocean waters
through which they swim, distributing plankton, nutrients, and thermal
energy to an amazing degree. In fact, these researchers hypothesize that
jellyfish may be as important a force in ocean mixing as are winds and
tides.
Not to belittle this role, but jellyfish do much more than provide food
for Ocean Sunfish and sea turtles.
Global Warming Update
In spite of this year’s very cool temperatures, the evidence of global
warming continues to pour in. In a collaboration between NASA and U. S. Navy
scientists, a new analysis has been conducted that considers greenhouse gas
emissions, volcanic activity, the Pacific Ocean phenomenon known as El Nino,
and solar radiation. El Nino is part of an ocean current shift that greatly
impacts Pacific fisheries while driving oscillations in global temperatures
and precipitation patterns. Volcanic activity actually cools the earth’s
climate by spewing cloud forming sulfurous gasses high into the atmosphere.
Solar radiation, however, is the most important and least understood
determinant of the global temperature. In a future Conservation Issues, we
will discuss the role of the sun’s variability in our climate changes.
The new analysis suggests that global temperatures over the next five
years could significantly exceed previous predictions. One interpretation of
this model suggests that, barring a major volcanic eruption, after next year
half of all years in the near future will be warmer that the warmest year of
all time, which was 1998. |