In the Red-Explaining the Red Tide Phenomenon

    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 redÖsometimes 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 gastrointestinal distress.

Reef Brief is a weekly column published in the San Pedro Sun
    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 mortality.

    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 recoverÖa trend that will hopefully continue.

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