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Why can some red tides harm fish, waterfowl, and humans?

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“mermaid's wine glass” algae — Algae The macroscopic genus of algae known as *Acetabularia* is commonly called “mermaid's wine glass” because of the distinctive umbrella-like shape of the tips of its stalks.

Red tides are harmful algal blooms, typically caused by dinoflagellates, that negatively impact marine life, birds, and humans through several mechanisms.123

These blooms can harm fish and other aquatic organisms by:
* Releasing Toxins: Certain species produce potent toxins that are lethal to fish and marine life upon contact or ingestion.124
* Physical Interference: Dense blooms can clog the gills of fish, leading to suffocation.3
* Oxygen Depletion: As the bloom decomposes or consumes resources, it can rapidly deplete oxygen levels in the water, causing mass die-offs.3

Waterfowl and other animals are often affected by consuming contaminated prey or through direct exposure to toxins in the water.13

For humans, the primary risks include:
* Consumption: Eating shellfish or finfish that have accumulated algal toxins can lead to severe poisoning, such as paralytic or amnesic shellfish poisoning.54
* Respiratory Irritation: When waves break, they can release wind-sprayed toxic cells into the air, which may cause respiratory distress or skin irritation for people near the coast.124