What causes algal blooms and why can they be dangerous?
A bloom of microscopic algae can produce enough toxin to poison entire coastlines and kill millions of fish.
The answer
Algal blooms occur when nutrients, particularly nitrogen and phosphorus from agricultural runoff, sewage, and industrial waste, fuel rapid growth of algae in coastal waters. While most blooms are harmless, harmful algal blooms (HABs) can produce potent toxins like domoic acid and saxitoxin that accumulate in shellfish and fish, poisoning marine mammals, seabirds, and humans who consume contaminated seafood. Some blooms deplete oxygen as they decompose, creating dead zones. HABs have increased in frequency and severity globally; the 2018 Florida red tide lasted over 16 months and killed hundreds of tonnes of marine life including manatees, dolphins, and sea turtles.
Source: CDC Harmful Algal Blooms
- algal blooms
- red tide
- HABs
- water quality
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