This paper provides an overview of harmful algal blooms (HABs), examining their natural and human-made causes, including weather events, ocean nutrient levels, and pollution. It discusses the detrimental effects of HABs on marine ecosystems and human health, tracing how toxins move through the ocean food web from phytoplankton to shellfish and ultimately to people. The paper also outlines prediction and mitigation strategies developed by organizations such as NOAA, including satellite monitoring, volunteer water-sampling networks, and toxin test kits. Economic impacts across fishing, healthcare, and tourism are addressed throughout.
Harmful algal blooms are formed by microscopic, single-celled plants that live in the sea. A bloom refers to a rapid proliferation of these single-celled organisms. While most algae species are non-toxic, some are not. The toxic species can produce neurotoxins that are transferred through the food web (National Environmental Satellite, Data, and Information Service, n.d.).
Harmful algal blooms can have various causes, both natural and human-made. They cause significant financial damages in four distinct ways: increased costs of commerce, increased healthcare costs, costs for maintaining and monitoring waterways, and negative impacts on tourism. Toxic blooms can, to some extent, be predicted.
Weather events can impact ocean conditions in a variety of ways. First, extreme events such as hurricanes, coastal storms, and floods can physically transport organisms from one part of the ocean to another, causing the kind of disruption that leads to a harmful algal bloom. Second, extreme weather patterns like El Niño and La Niña can cause temperature changes that affect growing conditions in the ocean (National Environmental Satellite, Data, and Information Service, n.d.).
Ocean nutrients play a role in algal blooms because blooms occur when nutrients are sufficiently abundant to feed the algae. Nutrient levels are influenced by other species in the water, temperature, and pollution (Backer & McGillicuddy, 2006).
Pollution may contribute to algal blooms because it can supply the nutrients that harmful algae need to survive and can kill the predator species that normally keep harmful algae levels within a safe range.
Over 200 species of algae — including dinoflagellates, diatoms, raphidophytes, prymnesiophytes, silicoflagellates, ciliates, and cyanobacteria — are either known to be or have the potential to be harmful or toxic to a wide variety of organisms (Landsberg, 2002).
Algal species can produce poisons or cause excess growth that leads to deaths in marine life, and the toxins can travel up the food chain and impact human life. The most commonly known fatal or harmful diseases that can result from algal blooms include: ciguatera fish poisoning, neurotoxic shellfish poisoning, paralytic shellfish poisoning, diarrhetic shellfish poisoning, and amnesic shellfish poisoning (National Environmental Satellite, Data, and Information Service, n.d.).
Non-fatal effects include the depletion of oxygen in the lower depths of the ocean (hypoxia) and the blockage of sunlight, both of which negatively affect growing conditions for other marine life.
Economic effects include impacts on the fishing industry, increased healthcare costs, maintenance and monitoring costs, and damage to tourism.
"How toxins travel from algae to humans"
"NOAA tools, satellites, and mitigation options"
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