Routine monitoring shows low occurrence of Pfiesteria so far this year. Pfiesteria identified in Chesapeake and Coastal Bays with healthy fish samples.

July 3, 2001

This is the third report of the 2001 season.

Pfiesteria and other algae.
Water samples have been collected since January and surveyed for Pfiesteria species (Pfiesteria piscicida and Pfiesteria shumwayae) using genetic probes developed by Dr. David Oldach (University of Maryland Biotechnology Institute). Between January 8th and June 20th, 224 water samples were collected from tributaries of Maryland's Chesapeake and Coastal Bays and tested for Pfiesteria. Samples collected from the Chesapeake Bay's tributaries (Pocomoke River, Transquaking River, Pokata Creek) and Newport Bay on the Coastal Bays have tested positive for Pfiesteria species (Table 1). Genetic probes provide information on the presence or absence of Pfiesteria in the water column but do not tell us about its toxicity. No unusual fish behavior has been observed and fish collected at these locations appeared healthy.

Table 1. Locations of positive Pfiesteria samples out of 224 samples collected between January 8 and June 20, 2001.


Positive Pfiesteria samples in 2001

Chesapeake Bay

Pocomoke River
(Tangier Sound)

May 21 (1 sample), June 5 (1)

Transquaking River

June 4 (1)

Pokata Creek

June 6 (1), June 20 (1)

Coastal Bays

Newport Bay

June 20 (1)

Fish and fish health.
Between June 30th and July 3rd, fish kills have been under investigation on the Magothy River, Botkin Creek, Stoney Creek, West River, Mill Creek, Severn River, as well as Rockhold Creek and Herring Bay. Initial investigations have reported low dissolved oxygen conditions in these areas. Algal blooms of Gyrodinium estuariale and small flagellate algae accompanied the low dissolved oxygen conditions at Stoney Creek. A variety of small algal species were producing bloom conditions at Herring Bay . Water samples have been collected and are being analyzed for their water chemistry, phytoplankton community and testing with the genetic probe for presence of Pfiesteria. No additional results are available at this time.

There were 24,394 fish collected during routine sampling for fish health monitoring on the Chesapeake and Coastal Bays from June 11th through June 21st. Less than 0.5 % of the fish showed any form of anomaly.

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

Water quality conditions.
The increased precipitation in late May and June has caused a slight decrease in salinity levels at monitoring sites on the Eastern Shore rivers (Pocomoke, Nanticoke, and Chicamacomico). After a period of high salinity levels in April and May, the increased precipitation has returned these levels to more average ranges in June. The water temperatures in the Bay and its tributaries are steadily increasing as the season progresses and have reached 27C in the Pocomoke by late June. The dissolved oxygen levels in the Pocomoke have stayed stable throughout the month of June and are generally within normal ranges for this time of year and are above 6 mg/L. Dissolved oxygen levels in the Chicamacomico have shown a large decrease through the month of June and by June 18th were around 3 mg/L. At most other monitoring sites on the Coastal and Chesapeake Bay tributaries, dissolved oxygen levels are above 5 mg/L and other water quality conditions are within normal ranges.

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