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August 8, 2003
Transquaking and Chicamacomico Rivers (Lower Eastern Shore, Chesapeake Bay) show elevated concentrations of blue-green algae.

Water samples collected by Maryland Department of Natural Resources field staff from the Transquaking and Chicamacomico Rivers on August 6th during routine water quality monitoring on Chesapeake Bay showed elevated levels of blue-green algae.

The Transquaking Creek sample showed Microcystis concentrations of 11,448 cells/ml and an additional 35,849 cells/ml of the blue-green algae Anabaena flos-aquae. These bloom concentrations are moderate when compared with Sassafras River samples this year that showed peak sample concentrations over 1.5 million cells/ml of Microcystis, however, the concentrations are considered bloom levels.

On the Chicamacomico River, concentrations were again more moderate than the Sassafras River but contained Microcystis at densities of 4,240 cells/ml and combined Anabaena species counts of 29,529 cells/ml.

Microcystis, Anabaena and Aphanizomenon may contain toxins that can cause health problems in humans and animals that come in contact with or drink the water. Maryland Department of Natural Resources collected samples of blue-green algae from the Sassafras River on July 22, 2003 and have submitted them to laboratories for analysis of toxin content. Results are expected in two to three weeks (see HAB News from August 7, 2003: "Betterton Beach (Sassafras River, Chesapeake Bay) closed due to bluegreen algal bloom."). In hot weather, and especially in still water with high levels of nutrients, blue-green algae can grow and accumulate rapidly, causing a bloom. Cases of human illness this year have included itching and rashes from contact with bloom waters, people should take common precautions to reduce the risk of illness or discomfort related to blue-green algal blooms:

  • The public should not swim in areas where blue-green algae bloom is evident. Do not drink water from any area with the appearance of a blue-green algae bloom.
  • 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. Blue-green algal blooms may contain toxins that could be harmful or fatal to pets and livestock.

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 upper Bay region in 2000.

A Press Release regarding conditions on the Sassafras River was published by Maryland Department of the Environment July 22nd and may be referenced for further information on blue-green algal blooms in the upper Chesapeake Bay. A fact sheet on Microcystis and the 2000 bloom can be found on the Department of Natural Resources’ website at: www.dnr.state.md.us/bay/hab/microcystis2.html. Maryland Departments of Natural Resources and Environment will continue to monitor the situation and publish updates to the website as necessary. To report a fish kill or fish health related event, please call the Fish Health Hotline at (888) 584-3110, 24 hours a day.