Harmful Algal Blooms

HAB stands for Harmful Algal Blooms. While Algae are vitally important to the health and well-being of all sorts of marine organisms, certain types and quantities of them can be harmful to their environment. Just like other forms of algae, HABs can occur in estuarine, freshwater, and saltwater environments. There are two main dangers associated with HABs, toxicity and oxygen deprivation. Some HABs are harmful because the algae involved release toxins that can be harmful or even fatal to a variety of marine organisms, particularly shellfish that concentrate the toxins and cause a variety of symptoms in the animals that consume them, including humans. Symptoms can include gastrointestinal issues, liver problems and various epidermis irritations among others. HABs have been a culprit in the deaths of many different animals, from whales to sea lions to salmon to birds. (WHOI 2007) The other primary danger of HAB’s is their quick growth and opaque nature. As these HABs form, they block the sunlight that many organisms need for photosynthesis and at the same time, to fuel their rapid growth, they use up the oxygen in the water that denies it’s use to other marine organisms. The water becomes unable to support life. These situations are also called “Red Tides” which refers to the color that often occurs in the water where these HABs occur.
Scientists believe that HABs are on the rise over the last several decades, but why? www.bigelow.org states “Scientists have offered numerous explanations.” One factor may be invasive species of algae introduced through the emptying and filling of ballast tanks on ocean going vessels. A second possible explanation is that certain algae are inhibiting grazers, organisms that eat algae, so the grazers are physically unable to control the algal population. Another possible explanation that has also been suggested is that human activity has played an integral role in an increase of harmful algal blooms by increasing the amount of pollution and nutrients released into the environment and other unintended effects such as habitat destruction of watersheds and other environments tied closely into the shoreline ecosystems.. It is also possible that the number of HABs has not actually been increasing, but that the increase in detection and knowledge allow scientists to recognize and classify them more effectively. (bigelow)




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