Pfiesteria Monitoring Update
October 23, 2001

This is the seventh report of the 2001 season.

Fish Health and Pfiesteria monitoring.

Eastern Shore including Coastal Bays:  During September and early October, Maryland DNR and Department of the Environment have responded to fish health events in Chesapeake Bay on Warwick Creek (tributary of the Choptank River), Wicomico River, Kings Creek and Back Creek (tributaries of the Manokin River), Wetipquin Creek (tributary of the Nanticoke River), Monie Creek, and the Big Annemessex River (see Figure 1a and Figure1b below). In the Coastal Bays, a fish kill was also reported on Marshall Creek (see Figure 1b below). Only water samples collected at the event site from Warwick Creek on September 22nd tested positive for Pfiesteria. During routine monitoring, samples from the Chicamacomico River tested positive for Pfiesteria on September 4th (2 samples), 24th (1 sample) and October 9th (1 sample). One positive sample was recorded on Pokata Creek (Fishing Bay) on September 12th. Follow up sampling of Pokata Creek has shown negative results for Pfiesteria.

Western Shore:  
Routine monitoring samples collected from Middle River on September 6th showed 10 samples were positive for Pfiesteria. On September 20th a fish kill was reported on Middle River, a region that has experienced fish health events each of the last two years. Water samples collected from Stansbury Creek on Sept 20th  and 27th, and from Frog Mortar Creek on September 25th  and 27th tested positive for Pfiesteria (see Figure 2a below). Pfiesteria remains active in the water column on the Middle River as sampling on October 11th showed 11 positive samples from the main channel and tributaries. 

On September 26th, Bullneck Creek off of Bear Creek on the Patapsco River system had a small fish kill of approximately 500 silversides and killifish. Dissolved oxygen levels were extremely low at 0.27 to 1.2 mg O2/L. A strong sulfur odor was evident in the area typical of the release of hypoxic to anoxic waters enriched with sulfur bacteria. A small fish kill on Stoney Creek of the Patapsco River was investigated on September 30th. Low dissolved oxygen or an inversion was described as the probable cause. Colgate Creek was also observed to have an algal die off and sulfur odors in the associated area during September (see Figure 2a below).

Cockey Creek on the Magothy River experienced a fish kill on September 17th; water samples were negative for Pfiesteria (see Figure 2b below). On the Severn River on September 13 there were 50 menhaden collected that looked healthy from an area of abundant gull activity. One water sample was collected. On September 14 evidence of algal blooms, algal die off and releases of sulfur bacteria were found on the river. Low dissolved oxygen levels were measured over a wide area. On September15, more than 300 fish were found in a kill associated with a broad region of low dissolved oxygen waters (see Figure 2b below). 

Overall results from the genetic testing of water samples for Pfiesteria.

As of October 17th, 13% (131 of 1005) of all water samples collected for 2001 (routine monitoring and rapid response events) were positive for the presence of Pfiesteria.

A reminder - please report fish kills, sick fish or fish with lesions to the Maryland Fish Health Hotline at 1-888-584-3110.

General notes on water quality condition.

Flow conditions for the Chesapeake Bay overall have been below average since May and with the exception of April, flows into the Bay remain below average for the year.  Since the end of September, conditions at Nassawango Creek, Snow Hill, MD on the Pocomoke River are largely below the median discharge levels for the 50-year data set in the area.

Salinities had been increasing throughout September in response to lower flow conditions. Rain storms in late September and early October resulted in a decline of salinity levels with runoff and increasing flows at the continuous monitoring stations for Rehobeth on the Pocomoke River, Drawbridge at the Chicamacomico and Decoursey Bridge on the Transquaking River (see charts below).



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