Algal bloom red tide algae10/4/2023 Domoic acid can be concentrated by shellfish and poisonous to humans who eat the shellfish. They take their name from their twirling motion and their whip-like flagella.ĭOMOIC ACID: A neurotoxin produced by the algae that cause red tide (coastal algae blooms). Brevetoxins can be concentrated by shellfish and poisonous to humans who eat the shellfish.ĭINOFLAGELLATE: Small organisms with both plant-like and animal-like characteristics, usually classified as algae (plants). Blooms near coasts are sometimes called red tides.īREVETOXIN: Any of a class of neurotoxins produced by the algae that cause red tide (coastal algae blooms). WORDS TO KNOWĪLGAL BLOOM: Sudden reproductive explosion of algae (single-celled aquatic green plants) in a large, natural body of water such as a lake or sea. If so, a consequence of global warming could be more algal blooms and more cases of marine toxin-related illness. Although the cause of the increased number of blooms is not absolutely certain, a general consensus among scientists is that the documented warming of the coastal oceans has made conditions more favorable for algal growth. National Oceanographic and Atmospheric Administration (NOAA) show that the frequency of algal blooms has increased along the coasts of the United States and other countries since the 1970s. Studies by researchers at the Woods Hole Oceanographic Institution and the U.S. These dinoflagellate species are eaten by a wide range of organisms, including mussels, soft-shell clams, sea scallops, oysters, lobsters, crabs, salmon, herring, mackerel, whales, sea birds, and sea otters. The dinoflagellate species Alexandrium spp., which are especially common along the coasts of the North Atlantic Ocean and the Pacific Ocean of North America, are associated with red tides in these areas. Red tides also occur in the northeastern part of the United States. Because of this color variance, scientists usually prefer the term “algal bloom” to the term “red tide.” Red tide is used most frequently in the United States, while algal bloom is more often used in other parts of the world.Ī particular species of dinoflagellate called Karenia brevis is often responsible for the red tides that occur in the waters of the eastern Gulf of Mexico. The water can appear to be colored from white to nearly black, but usually the water looks reddish or brown, depending on the species. When this happens, the term “algal bloom” is used to describe the various species of phytoplankton that are involved.īecause various phytoplankton species contain pigments of different colors-ranging from green to brown to red-they can turn water different colors depending on which types of phytoplankton have grown to large enough concentrations. However, sometimes phytoplankton grow (bloom) so fast that they become visible on the surface of the water. ![]() In fact, they are beneficial as a food source for larger fish and mammals. Most species of phytoplankton are not harmful to humans. Historical Background and Scientific Foundations Toxins can become airborne, as well when winds set inland during a large red-tide algal bloom off the coast of Florida, for example, asthma attacks send an increased number of people to hospital emergency rooms. In such cases, these HABs can be eaten by fish, birds, marine mammals, and humans, causing adverse symptoms and, sometimes, death. This reddish discoloration is the source of the term “red tide.” When these toxins are present in the dinoflagellates causing the “red tide,” it is termed a harmful algal bloom (HAB). When dinoflagellates that contain various natural neurotoxins-such as brevetoxin, domoic acid, and saxi-toxin-occur in large enough concentrations, they can cause heavy and murky spots of reddish, discolored surface waters. Sudden large increases in their numbers are thought to be attributable to changes in salinity, temperature, and water depth, and sometimes to human activities such as the addition of nutrients to water from agricultural runoff. These organisms are called dinoflagel-lates and are a type of phytoplankton that live in marine and freshwater habitats. Red tide is a type of algal bloom, which is a sudden, large increase in the number of microscopic organisms living in a body of water.
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