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Water samples were collected coincident with the Chesapeake Bay Long term Water Quality Monitoring Program by Maryland Department of Natural Resources (DNR) staff below the Rt. 301 of the Potomac River on Friday, June 16, showing bloom densities of the non-toxic dinoflagellate Heterocapsa rotundata . Heterocapsa dominated the samples with 19,050 cells/ml and 27,940 cells/ml. Coincident with sampling in the region, Hank Helmen, a volunteer of the Chesapeake Bay Foundation was conducting an aerial overflight in the area and photographed the bloom waters largely hugging the Virginia side of the river on this day. (See photo's, used with permission of the Chesapeake Bay Foundation, Richmond , VA ).
Salinity measures have been above average this year in the tidal Potomac River . The DNR Eye's on the Bay website shows data for long term monitoring site RET2.4 located at the Route 301 Bridge with salinity measured for June at 8.25 ppt, near record high levels for the month (Maximum salinity measured for June since 1985 is 8.32 ppt). River flows have been largely below average as measured at Little Falls allowing more of the Bay related water to push upriver into this region. Such drought effects and resulting habitat changes along the river can allow organisms more commonly found in the river mouth and Bay, like Heterocapsa , to occur farther upstream that normal. Similar events occurred in 2002 when an unprecedent Dinophysis bloom was detected in winter on this same stretch of river. However, elevated salinity in an area that is typically considered freshwater to low salinity can stress such Bay life as aquatic grasses. Bottom water dissolved oxygen levels had reached record low levels in May (1.95 mg/L ) but show evidence of rebounding to 3.15 mg/L during June. The DNR Swan Point Continuous Water Quality Monitoring Station, located on the Maryland side of the Potomac River downstream of the Rt. 301 bridge has shown dissolved oxygen conditions since April nearly always above 5 mg/L (as measured 1 meter below the surface). Such levels are considered healthy for the majority of Bay life. In June there have been brief episodes of dissolved oxygen dipping below 5 mg/L, but not reaching the highly stressful to lethal hypoxic (0.2 - 2 mg/L) or typically lethal anoxic (<0.2 mg/L) conditions. The MD DNR in coordination and cooperation with Department of Health and Mental Hygiene and Maryland Department of the Environment will continue to monitor algal blooms throughout the state. For up to date information on all of Maryland 's harmful algal blooms and water quality, please visit Eyes on the Bay at www.eyesonthebay.net The Chesapeake Bay Safety and Environmental Hotline is a toll-free phone number for Maryland citizens to call to report a problem on the tidal portions of Maryland 's portion of the Chesapeake Bay as well as the Coastal Bays . One phone call will now direct citizens to the appropriate agency to make a report 24 hours a day, 7 days a week. Maryland Department of Natural Resources will continue to actively monitor and report on the condition of the river. Citizens are advised to take common precautions around bloom waters to reduce the possible risk of illness or discomfort related to blue-green algal blooms:
Please note that illness associated with harmful algal blooms is now a reportable illness so physicians should be reporting these to local health departments. The MD DNR in coordination and cooperation with DHMH and MDE will continue to monitor all blue-green algal blooms throughout the state. For up to date information on all of Maryland's harmful algal blooms and water quality, please visit Eyes on the Bay |
