Tuesday, March 13, 2012

Red Tide Effects On Marine Life

Red tide algae contains toxins that can harm marine life.


Red tide, also known as Harmful Algal Blooms, is a phenomenon caused by explosive algal blooms, resulting in the discoloration of the water. Red tides are a natural occurrence and global in scope. However in recent years red tides are occurring more frequently and affecting larger areas. Red tide algae can produce natural toxins that can be harmful or fatal to marine life.


Causes of Red Tide








Red tides can result from warm ocean surface temperatures, low salinity (low level of dissolved salt in water), high nutrient content, calm seas and rain followed by sunlight. Red tides can also be carried great distances by wind, currents, storms and ships. While Red tides are a natural occurrence, they have increased in frequency and magnitude since the 1980s. Other factors suspected in the increased severity of red tides include nutrient enrichment from human population growth and land practices, generally farming. Warmer water temperatures as a result of global warming is also believed to be causing more severe red tides.


Types of Harmful Toxins Found in Red Tides








Most microscopic life, including algae, represent an essential part of marine habitats. However, some species of algae found in red tides release harmful toxins. For example, Alexandrium fundyense is found in red tides that occur along the Atlantic coast stretching from Canada to southern New England. Alexandrium catenella is found in the Pacific coast from Alaska and California. Karenia brevis is common in the Gulf of Mexico along the west coast of Florida.


Spread of Toxins Through Bioaccumulation and Biomagnification


The potent toxins released by harmful algae blooms can be hazardous to marine life in several ways. Harm comes about through the process of bioaccumulation, the increase in concentration of the toxin from the algae to the first organism in a food chain, and biomagnification, the increase in concentration of the toxin from one link in a food chain to another. For example, krill feed on the algae resulting in bioaccumulation, the sum total of algae consumed by krill. Larger fish eat several or more krill resulting in biomagnification. This process continues, increasing the toxicity through the food chain.


Direct Effects of Red Tides on Marine Life


Algae in red tides have negative impacts on certain species of marine life. The Florida Fish and Wildlife Conservation Commission observed that 17 species of marine invertebrates normally found in Tampa Bay disappeared after a red tide. Red tide events have also caused fish kills (fish killed in large numbers) and stranding of manatees and whales. For example, a red tide event in the Georges Bank in the Gulf of Maine resulted in the death of 19 humpback whales.

Tags: marine life, food chain, concentration toxin, concentration toxin from, increase concentration, increase concentration toxin
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