Routine monitoring shows Pfiesteria presence on Lower Eastern Shore tributaries, fish are healthy. Localized blooms of other harmful algae being reported.

June 20, 2001

This is the second 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 5th, 181 water samples were collected from tributaries of Maryland's Chesapeake and Coastal Bays and tested for Pfiesteria. Samples collected from the Pocomoke River system on May 21 (1) and June 5 (2) as well as the Chicamacomico River (1) and Pokata Creek at Fishing Bay (1) have tested positive for Pfiesteria species. 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.

Blooms from other HAB species have been uncommon so far this year. Prorocentrum minimum, a species of dinoflagellate that has been known to produce large areas of mahogany tides in Chesapeake Bay in the past, has reached low bloom densities in localized regions. The Prorocentrum bloom has not become as prevalent as the bloom of 2000. Colonial bluegreen algae including Microcystis, Anabaena and Aphanizomenon species can dominate algal communities in some tidal waters during the summer and are just beginning to show up in very low densities from water samples in the Chesapeake (Potomac River with higher densities recently observed in the Sassafras River) and Coastal Bays. Evidence of localized brown tide (Aureococcus anaphogefferens) blooming in the Coastal Bays was observed in early June.

Fish and fish health.
Fish sampling for the Pfiesteria monitoring program began in June. In Coastal Bays tributaries, 516 fish comprised of 7 species were captured from sites on Newport Creek and the St. Martin River. Menhaden comprised 70% of the catch. All fish appeared healthy with no external anomalies.

On the Chesapeake Bay tributaries, 3,375 fish comprised of 13 species were collected on June 5th from the Pocomoke River. There were 1,595 menhaden collected and less than 1% showed some form of anomaly. On the Tred Avon River, 492 fish of 6 species were collected on June 12th and all the fish appeared healthy.

On June 4th, a small white perch kill (9 fish found at the site) was investigated on Patapsco Creek. The water was slightly green from algae but water quality conditions were within normal ranges when measured an hour after the call was received. Water samples tested negative for Pfiesteria.

A reminder - please report fish kills, sick fish or fish with lesions to the Maryland Fish Health Hotline at: 1-877-224-7229.

Water quality conditions.

After below average flows into the Bay during the winter months of 2001, increased precipitation allowed for average flow conditions from late March through April. This period was followed by decreased inflow due to reduced rain in late April and May. Salinity levels at monitoring sites on Eastern Shore rivers (Pocomoke [see chart below], Nanticoke, and Chicamacomico) were increasing in response to lower flows but recent rains and flow increases have salinity within the seasonal range for early June. In the first week of June within the Pocomoke River, a slight oxygen sag under 5 mg/L is evident in the vicinity of Shelltown but the estuary remains largely above 6 mg/L. For most monitoring sites on the Coastal and Chesapeake Bay tributaries dissolved oxygen concentrations measured during the day in late May and early June were typically above 5 mg/L.

Chart showing the increase in Salinity through April and May 2001 at Williams Point on Pocomoke Sound

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