The Red Waters Around the World

Mysterious Earth | | August 25, 2010 at 1:11 am




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What is a red tide?

This is a naturally-occurring concentration of a microscopic alga called Karenia brevis (which was formerly known as Gymnodinium breve). In some cases, under certain kinds of environmental conditions, these microscopic algae will be able to grow and multiply quickly. This will end up creating blooms which will make the ocean appear brown or red to the people. People often call these blooms the ‘red tide’, owing to the color that the water takes on.

This organism is capable of producing a toxin which is known to affect and debilitate the central nervous system of fishes. This ends up paralyzing the fishes that are no longer able to breathe normally. As a result of this phenomenon, the red tide is often known to result in masses of dead fishes which end up washing up on the Gulf beaches.

Red Tide

What causes red tides?

The first occurrence of the red tide might even have found its mention in the Bible. The first among the 10 plagues of Egypt, which have been spoken about in the book of Exodus, might actually indicate the existence of a red tide even then. The passage says “And all the waters that were in the river turned to blood… and the fish of the river died and the water stank…”

The red tide is a natural phenomenon and nothing that has been caused by humans. When the temperature, nutrients and salinity of the water reaches certain levels, the algae K brevis gets a chance to reproduce itself. Some experts pinpoint the cause of a red tide at the combination of higher temperatures and a lack of rain and wind. There is no known way in which humans can change or control the occurrence of a red tide, since it is completely and wholly a natural phenomenon. Scientists around the world have been studying the red tide to figure out how it works and what can be done to avoid the kind of damage that this occurrence is capable of bringing with it.

What causes red tide

Known Occurrences of Red Tides

Red tide occurrences have been seen and documented at various places around the world. Both sides of the Atlantic, off Florida and along the waters of the Pacific coast (into Alaska), for instance, have seen red tide occurrences in the past.

During March 1994, South Africa ended up experiencing the worst ever records of marine mortality.  This happened in the west coast area of the St. Helena Bay. This damage was caused due to the existence of a red tide in that area. The marine life was being affected and this was caused due to the suffocation and poisoning that came with this natural phenomenon.  Most of the mussels, sea urchins and limpets were dead. The only fish that seemed rather unaffected was the false limpet (Siphonaria capensis) which is capable of switching over to what is called anaerobic metabolism when there is an acute absence of oxygen.

Red Tide

Is it safe to consume the fish at these times?

Shellfish are said to be the worst affected when it comes to red tides. The algae is said to become concentrated in these fishes – mussels, oysters, clams, quahogs, and other kinds of bivalves. The shellfish themselves may not be as affected by the red tides; but they definitely won’t be suitable for consumption.

Fishes like lobsters, shrimp and crabs are safe to eat, even if they’ve been caught in red tide water.

People who consume shellfish with the toxin from the algae might actually end up suffering from PSP (Paralytic shellfish poisoning).  A few clams, and you could be affected.

Red Tide fish

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