As much as scientists and researchers know about the ocean, there are
still many things yet to be discovered and/or explained. One phenomenon
that still puzzles scientists is the occurrence of a "red tide," an event
that arises when microalgal species increase in abundance and ultimately
discolor the water. This naturally occurring event has taken place around
the world for centuries causing a variety of negative impacts. While the
basic background of red tides can be explained, many questions remain as
to how and when this event takes place. Here's what we do know.
At the base of the food chain are microscopic
single-celled algae, or dinoflagellates, which comprise some of the
energy-producing plants found in the sea. Occasionally, algae can grow
fast or "bloom" which results in dense and visible patches of varying
color in the water. Most species are not harmful, but there are a few
species that produce toxins, which are apparently the most potent in the
world. A "red tide" describes an event when these toxic producing
microscopic algae that contain red pigmentation bloom, resulting in a red
patch in the water. It should be clarified, though, that red tides have
nothing to do with tidal activity, nor are they always red—sometimes they
are reddish brown, yellow, or green in color.
Red tides can become a problem because of their domino
effect in the food chain. When these tiny plants undergo an algal bloom,
they are consumed in enormous quantities, particularly by clams, mussels,
and oysters. These filter-feeding animals draw in large quantities of
water and filter the food, often leaving behind a high concentration of
the harmful algae in their system. Thus, after a shellfish consumes the
algae, a human will often consume the shellfish, leading to problems.
This is why humans are often warned not to consume certain seafood in an
area affected by a red tide. If a human does ingest the shellfish
containing neurotoxins, symptoms usually include dizziness, numbness, and
It's almost impossible to predict where a red tide
event will take place, considering they have occurred along most coasts.
The most common sites are along the Florida coast, the Gulf of Mexico,
and along the Mexican coast. In Florida, red tides usually occur in late
summer and fall, but they've also occurred in just about every month.
During an event, fish affected by the neurotoxin become paralyzed and
stop breathing, eventually washing up on the beach. Unfortunately, aside
from fish, the primary victims of red tides in Florida are manatees. In
1996 alone, 149 of these endangered species died from red tide-related
deaths. Fortunately, Belize has not had to endure quite as many red tide
events, though there was a relatively severe occurrence approximately
twenty years ago, resulting in high fish
What is so baffling about red tides is
that humans cannot control them. Some believe that the blooms are
triggered by just the right temperature, salinity, and nutrient levels in
the water. Others feel that it is the combination of increased
temperature and lack of rain and wind that cause a bloom to occur.
Whatever the cause, red tides are certain to be around for many years to
come. The environment has always found a way to recover—a trend that will
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