Update on HAB and SAV Forecasts

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Update on HAB and SAV Forecasts
Peter Tango and Peter Bergstrom
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June 2005 no cyanobacteria blooms
detected on the Potomac River.
July 11- Microcystis abundances
Indian Head 4763 cells/ml Mattawoman Crk 27
60 cells/ml Possum Point 1144 cells/ml Smith P
oint 5302 cells/ml Maryland Point 1852 cells/ml
No cyanobacteria cells detected at the remaini
ng stations Bloom concentration considered 10,0
00 cells/ml
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Potomac HAB Forecast Update

• Forecast that June bloom would occur like spring
  Mahogany tide, this one appears to be weeks
  behind expectation.
  
• Forecast 16 km distribution Microcystis
  distribution is 16 km but not yet at bloom
  levels. Currently, nearshore accumulations likely
  exceed bloom levels.

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• The 2005 SAV forecast issued in late May was
• Low-salinity SAV area would have large
  increase
  
• High-salinity SAV area would also increase
• Medium-salinity SAV area was expected to remain
  relatively unchanged

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SAV Forecast Update

• First aerial photographs of high-salinity zone
  suggest about the same area as in 2004.
  
• Limited information on the medium- and
  low-salinity SAV communities.
  
• Medium-salinity SAV area is largely widgeongrass
  - ground surveys in the Choptank (where the
  largest areas of widgeongrass are found in a good
  year) suggest that it may do well this year.
• Low-salinity SAV reports are promising, with
  dense and diverse grass beds reported in several
  areas.

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Encouraging Development

• Native dark false mussels helped clear the water
  in the Patapsco, Chester, Magothy, Severn and
  South rivers and Eastern Bay in 2004.
  
• Started to re-appear in early July this year in
  the Magothy and Chester (later than last year).
  
  
• Water clarity has started to improve near mussels
  in the Magothy, and numerous small beds of
  redhead grass have appeared in areas of the upper
  Magothy that had mussels last year, but have not
  had any redhead grass for many years.