Harmful Algae Blooms
What are Harmful Algae?
Algae are a natural and critical part of our Chesapeake and Coastal Bays ecosystems. Algae, like land plants, capture the sun’s energy and forms the foundation of the food web that supports fish and shellfish. They occur in a size range from tiny microscopic cells floating in the water column (phytoplankton) to large mats of visible “macroalgae” that grow on the bottom.
Algae may become harmful if they occur in an unnaturally high abundance or if they produce a toxin. A high abundance of algae can block sunlight to underwater bay grasses, consume oxygen in the water leading to fish kills, produce surface scum and odors, and interfere with the feeding of shellfish and other organisms that filter water to obtain their food. Some algal species can also produce chemicals that are toxic to humans and aquatic life. Fortunately, of the more than 700 species of algae in Chesapeake Bay, less than 2% of them are believed to have the ability to produce toxic substances.
Are all algae harmful?
No. While algae in large amounts can harm fish, only some algae have been shown to produce harmful chemicals that affect humans and animals directly.
What are the effects of harmful algae, and how can they be prevented?
Fortunately, harmful algae are generally only harmful through direct contact. This contact can occur through skin contact or through accidentally swallowing water containing the algae. Some species can also produce toxins that accumulate in shellfish or other fish. Finally, some algae species have been found to produce toxins that can become airborne in small water droplets (aerosols) that are irritating to the skin.
How does Maryland protect the public from harmful algae?
The Department of Natural Resources, Department of the Environment, and Department of Health and Mental Hygiene cooperate with local health departments to protect the public from harmful algae while still enjoying Maryland’s many recreational beaches.
How can I found out about current beach conditions?
To find out about current conditions in the Chesapeake, go to the Eyes on the Bay, where you will find information about water quality, including the Department of Natural Resource’s monitoring program for harmful algae.
Whom do I contact to report a harmful algal bloom?
To report harmful algal blooms, if there are fish kills, fish health, or human health concerns associated with the observed algal bloom, please contact the Fish Health 24 hour helpline at (877) 224-7229 at any time.
What if I or someone I know has been exposed to harmful algae?
If you have questions about the health effects of harmful algae or you think you or someone you know is having health problems that could be related to harmful algae, you may contact the Infectious Disease and Environmental health Administration at the Department of Health and Mental Hygiene toll-free at (866) 703-3266. You can also contact your local health department.
- CDC HAB
- To Report a Harmful Algae bloom call: (410) 260-8630
- If you have been exposed to Harmful Algae call: (866) 703-3266