HAB Species

Algae are normal components of all aquatic environments, but can produce a “harmful algal bloom” or “HAB” when they bloom in significant numbers, lead to oxygen depletion, or generate toxins. HABs can harm marine organisms and some also impact human health.

A number of different algal species occur in Chesapeake Bay, either as single-species assemblages or multi-species aggregations. Here are the dominant Virginia bloom-formers that are potentially toxic.

Alexandrium monilatum

Easily visible when it produces a red tide or bioluminesces at night, this organism produces toxins that have been associated with mortality of oyster and fish larvae.

Chattonella subsalsa

This organism has been associated with fish kills and can produce brevetoxin-like compounds.

Cochlodinium polykrikoides

Prolonged exposure to this algal species can be harmful to organisms, particularly larval shellfish and finfish.


Species of Dinophysis produce toxins that can accumulate in shellfish to cause Diarrhetic shellfish poisoning (DSP) when the shellfish are eaten by people.