This naturally occurring event has taken place around the world for centuries causing a variety of negative impacts. While the basic background of red tides can be explained, many questions remain as to how and when this event takes place. Here's what we do know. Most species are not harmful, but there are a few species that produce toxins, which are apparently the most potent in the world. It should be clarified, though, that red tides have nothing to do with tidal activity, nor are they always red sometimes they are reddish brown, yellow, or green in color.
Red tides can become a problem because of their domino effect in the food chain.
When these tiny plants undergo an algal bloom, they are consumed in enormous quantities, particularly by clams, mussels, and oysters. These filter-feeding animals draw in large quantities of water and filter the food, often leaving behind a high concentration of the harmful algae in their system. Thus, after a shellfish consumes the algae, a human will often consume the shellfish, leading to problems. This is why humans are often warned not to consume certain seafood in an area affected by a red tide. If a human does ingest the shellfish containing neurotoxins, symptoms usually include dizziness, numbness, and gastrointestinal distress.