I’m Phoebe Zimmermann with the VOA Special English AgricultureReport.
Different events can change the balance of sea life. Red tidesare an example. These can happen in oceans, rivers or lakes anywherein the world. What happens is that algae suddenly increase innumbers. Algae are single-celled organisms. They are a normal partof sea life.
As they spread, or bloom, the water may turn red or brown.Sometimes the water does not change color at all. But deadly algaecould still be present.
Some kinds of algae produce a strong poison. This can build up inshellfish that eat the algae and make them poisonous, but not killthem. Other kinds of algae may kill sea life by reducing oxygenlevels in the water. In some red tides, thousands of dead fishappear on beaches.
Scientists do not know exactly why red tides happen. But they saya combination of conditions all play a part. These include watertemperature, nutrients in the water and water flow. Pollution couldalso play a part.
A number of different algae can cause red tides. A common formhas the scientific name Karenia brevis. It is often linked with redtides in the Gulf of Mexico and the Caribbean area.
Algae poisons build up in the tissue of shellfish like clams,oysters and mussels. This makes them unsafe for several weeks aftera red tide goes away.
People are also advised not to eat the organs of fish orshellfish like shrimp, crab or lobster. Scientist Richard Piercesays the poison produced by K. brevis does enter the meat of thesecreatures. But he adds that there have been no reports of peoplegetting sick from eating healthy fish during such a red tide. MisterPierce is director of the Center for Eco-toxicology at the MoteMarine Laboratory in Florida.
There are different kinds of shellfish poisoning, some moresevere than others. Effects can include diarrhea, fever, stomach andmuscle pain, and breathing problems. In severe cases people can dieunless they receive treatment.
Experts say older people are especially likely to experiencesevere effects from algae poisons.
Some people who swim during a red tide report skin problems orshortness of breath. Scientists have more to learn about thepossible risks of swimming in red tides or breathing algae poisonsin the air.
This VOA Special English Agriculture Report was written by MarioRitter. I’m Phoebe Zimmermann.