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Harmful Algae Threaten US Waters, Health
26 Jun
Summary
- Algal blooms impact people, marine life, and economies.
- Climate change and pollution worsen harmful algal blooms.
- Blooms can produce toxins or deplete oxygen in water.

Harmful algal blooms (HABs) represent a significant and expanding threat across all U.S. coastal and Great Lakes states. These microscopic algae colonies can severely impact the health of both people and marine ecosystems. NOAA reports that HABs also pose economic risks, especially to coastal communities dependent on fishing and tourism.
The frequency of these blooms may increase due to climate change and elevated nutrient pollution. HABs can generate toxins harmful to humans, fish, shellfish, marine mammals, and birds. While severe human illness is rare, it can be debilitating or fatal. Some blooms, though not toxic, consume oxygen as they decay, harming aquatic life, or can discolor water and contaminate drinking sources.
In Florida's Gulf of Mexico, Karenia brevis is a common culprit, causing 'red tides.' Scientists can forecast red tide movements, but bloom duration varies from weeks to over a year, influenced by factors like nutrients, salinity, and sunlight.