Blue-Green Algae Blooms Resuface In Harford County Waters
Citizens Urged to Use Caution When Recreating
BALTIMORE, MD – The Maryland Departments of Natural Resources and the Environment today advised Marylanders to take precautions when swimming, boating or recreating in certain waterways this holiday weekend as blue-green Microcystis algae blooms have been positively detected.
Current surveys show that a Microcystis bloom has been observed along the Bush River, Harford County, MD. Blue-green algae naturally occur in tidal freshwater portions of the Chesapeake Bay and its tributaries. However, algal blooms may periodically use up oxygen, causing fish to suffocate and die. Affected waters may also appear as if a blue-green to yellow-green paint is floating on the surface of the water. Major blue-green algae blooms were last reported in the region in 2000 and 2003.
Although there have been no reported cases of human illness, people should take common precautions to reduce the risk of illness or discomfort related to Microcystis:
Microcystins are not known for being prone to bioaccumulate in fish or shellfish. In hot weather, and especially in still water with high levels of nutrients, blue-green algae can grow and accumulate rapidly, causing a “bloom.” The excess nutrients and poor flushing in the Chesapeake Bay and its tributaries contribute to these types of conditions.
- The public should not swim in areas where a blue-green algae bloom is evident. Do not drink water from any area with appearance of a blue-green algae bloom. Some strains of Microcystis produce toxins; gastrointestinal discomfort, headache, diarrhea and potential liver damage may occur from ingesting concentrated blue-green algal bloom waters.
- If contact is made with problem water, simply wash off with fresh water. In some cases, skin irritations may occur after prolonged contact. If irritations persist, see a physician or local health care provider.
- Keep pets and livestock away from bloom areas. Microcystis blooms may contain a toxin that could be harmful or fatal to pets and livestock. Environmental conditions may be appropriate for the development of blooms in other freshwater parts of the Chesapeake Bay and the tributaries as the summer progresses.
Algae are a natural and critical part of our Chesapeake and Coastal Bays ecosystems. Algae, like land plants, capture the sun’s energy and support the food web that leads to 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 bottom sediments.
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.
A fact sheet on Microcystis and the 2003 bloom conditions can be found on the Department of Natural Resources website at: www.dnr.state.md.us/bay/hab/microcystis2.html. To report human illness from bloom water contact, a fish kill or fish health-related event, call the Fish Health Hotline at (888) 584-3110, 24 hours a day.
Posted May 28, 2004