What are the causes and effects of saltwater algal blooms?

Answer 1

Scientists are not sure why some populations of saltwater algae increase rapidly at times. But red tides occur most often when there is an increase in nutrients in the water. Saltwater algal blooms are commonly called red tides because the algae that grow rapidly often contain red pigments and turn the color of the water red. Some red tides occur regularly in certain seasons. For example, the cold bottom layers of the ocean contain a lot of nutrients. When this cold water mixes with the surface waters, more nutrients become available to surface organisms. With greater concentrations of nutrients present in the surface waters, blooms of algae occur. Increases in ocean temperature due to climate changes also affect the occurrence of red tides. Red tides are dangerous when the toxins that the algae produce become concentrated in the bodies of organisms that consume the algae. Shellfish, such as clams and mussels, feed on large numbers of the algae and store the toxins in their cells. Fishes may also feed on the algae and store the toxins. When people or other large organisms eat these shellfish and fishes, it may lead to severe illness or even death. Public health officials close beaches in areas of red tides to prevent people from fishing or gathering shellfish.