Freshwater Algae Blooms: Contributing Factors and Health Concerns Massachusetts Department of Public Health, Bureau of Environmental Health What are algae blooms? Algae blooms form when cyanobacteria (also known as blue-green algae), which are photosynthetic bacteria that grow in water, multiply quickly and form scums or mats on MDPH Guidelines the surface of the water. Cyanobacteria are a natural part of the ecosystems of lakes and ponds, but can MDPH reviewed World Health Organization guidance and current scientific cause problems when they undergo explosive growth. Blooms in New England are literature in order to develop a protocol for evaluating potential health concerns most common in summer. related to the presence of cyanobacteria. Depending on the severity of the bloom the water could range from appearing The ability of cyanobacteria to multiply quickly makes monitoring their numbers slightly colored to resembling pea soup or paint. Blooms frequently appear blue or important. Because health risks rise with cell counts, the goal of any monitoring green but could be another color, such as brown or red. plan is to be able to take action before levels are reached that pose health risks. Algae blooms can cause odor and taste issues in the water, fish kills, and illness in humans and animals. Decomposing blooms can rob the water of the dissolved oxygen MDPH recommends an advisory or closure when: vital to fish and other aquatic life. • A visible scum or mat layer is present In addition, certain species of cyanobacteria can manufacture toxins which pose a • The blue-green algal cell count exceeds 70,000 cells/milliliter health risk to people and animals coming in contact with or ingesting the water. • The microcystin level of lysed cells exceeds 14 parts per billion (ppb) Health Concerns • Health concerns related to algal toxins vary depending on the type of exposure (contact or ingestion) and the concentrations of toxin present. Contact with high levels of cyanobacteria has been found to contribute to eye, ear, and skin irritation. Ingestion can lead to more serious health effects such as muscle cramps or twitching. • If elevated levels of the algal toxin microcystin are present in the water and ingested, serious liver damage can result. Exposure to elevated levels of the algal toxin anatoxin can cause serious neurological damage. Small children and pets are more susceptible than adults to the effects of toxins. Livestock and pet deaths from ingestion of algal toxins have been reported. • If you see water that appears to have an algae bloom, do not come into Contributing Factors contact with or ingest the water. Treating water by boiling does not get rid of any toxins present. Prevent contact and ingestion by kids and pets. • Certain environmental conditions, such as warm weather, sunlight, and an • Dogs can get very ill and even die from licking algae out of their fur. Rinse abundance of nutrients in the water, are more favorable to the rapid growth of dogs off immediately if they come into contact with water with an algae scum or blue-green algae. bloom. • Excess levels of nutrients in water bodies can come from anthropogenic, or human-related, sources. Phosphorus and nitrogen, which are found in human and animal waste and fertilizers, are two important nutrients used by blue-green For More Information or To Report a Bloom algae in their growth. Vanessa Yandell is the Algae Project Coordinator for the Massachusetts • Examples of sources that can input large amounts of nutrients to water bodies Department of Public Health, Bureau of Environmental Health are agricultural activities, leaking septic or sewer systems, stormwater runoff, lawn fertilizers, and pet and wildlife waste. Phone: 617.624.5757 Email: Vanessa.Yandell@state.ma.us • People can lessen the inputs of these nutrients to water bodies by properly Website: www.mass.gov/dph/topics/environmental_health maintaining septic systems, planting or maintaining native vegetation around the water’s edge, using low- or no-phosphate dishwasher detergent, applying fertilizer correctly, and picking up pets’ waste. Do not feed birds or geese. Additional Resources: U.S. Centers for Disease Control and Prevention: http://www.cdc.gov/hab/ • It is also important to realize that most storm drains empty directly into water U.S. Environmental Protection Agency: bodies without treatment. Never put or pour anything into a storm drain. Wash http://www.epa.gov/nheerl/clean_water/hab/ your car on your lawn or at a commercial car wash instead of on your driveway. Avoid fertilizing onto pavement or directly into a storm drain.
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