| Imagine fishermen walking down to the
seashore, ready to carry out their early morning routine of preparing their
boats and net. {{U}}(1) {{/U}} they hope for a good catch of fish. But
to their {{U}}(2) {{/U}}, a horrible sight meets their still sleepy
eyes. Thousands of fish have washed {{U}}(3) {{/U}} dead. The cause of
this mass destruction? A red tide! Red tides are a global {{U}}(4) {{/U}}. They have been observed on both the Atlantic and the Pacific coasts of the United States and Canada. They have also {{U}}(5) {{/U}} in many other places. Though relatively few people are {{U}}(6) {{/U}} them, red tides are not new. In the Philippines, a red tide was first seen in the province of Bataan in 1908. Since then, red tides have been seen in many other {{U}}(7) {{/U}}. A Philippines red tide expert told us that " {{U}}(8) {{/U}} the fish kills, the Philippines has documented 1, 96 cases of dead shellfish poisoning caused by red tides." The term “red tide”{{U}} (9) {{/U}} the discoloration of water that sometimes occurs in certain areas of the ocean or sea. Although the color is often red, it may also be {{U}}(10) {{/U}} of brown or yellow. The World Book Encyclopedia reports that "the discolored areas may range from {{U}}(11) {{/U}} a few square yards to more than 2,600 square kilometers." What causes such discoloration? Red tides are generally caused by several {{U}}(12) {{/U}} of single-celled organisms. These tiny organisms have hair-like projections which they use to {{U}}(13) {{/U}} themselves in water. There are about 2,000 varieties of these organisms, 10 of which carry poisonous {{U}}(14) {{/U}} These minute organisms usually stay in warm waters with high content of salt. A red tide occurs when there is a sudden and rapid {{U}}(15) {{/U}} of these organisms. The concentration of these organisms may {{U}}(16) {{/U}} to 50,000,000 per quart of water! Although scientists do not fully understand why this happens, it is known that these organisms {{U}}(17) {{/U}} when certain conditions simultaneously affect the water. These include abnormal weather, {{U}}(18) {{/U}} temperatures, an oversupply of nutrients in the water, a generous {{U}}(19) {{/U}} sunlight, and favorable water currents. When a heavy rainfall occurs, minerals and other nutrients are sometimes washed {{U}}(20) {{/U}} the land into coastal waters. These nutrients can contribute to the breeding of the organisms. The result? Red tides! |