Maryland's Pfiesteria Monitoring Activities

July 24, 1998 Update

Fish Health

Fish health monitoring by DNR's Resource Assessment Service, DNR's Fisheries Service and the University of Maryland Eastern Shore continues on 23 Maryland rivers and the Chesapeake Bay. Fish are sampled and examined through ongoing DNR fish health programs Bay-wide, as well as specific Pfiesteria monitoring activities on the Pocomoke, Manokin/Kings Creek, Chicamacomico, Nanticoke, Big Annemessex and Eastern Shore Wicomico Rivers and two coastal bay tributaries (St. Martin and Newport Bay).

Over the last three weeks, more than 48,300 fish were examined. Less than 1 percent had any sort of anomaly. The sampled fish were from trawls and seines from directed scientific activity and from samples from commercial and recreational fishermen. No Pfiesteria-like symptoms were observed.

An unusually large sample of 27,770 menhaden was collected in a 100-foot beach seine sample in the Wicomico. Only 10 of these fish exhibited any sort of skin anomaly and these may very well have been damage from the net collection. Juvenile menhaden are becoming a common component of the catch in all areas as they begin to move into the creeks and rivers.

Fish Health Hotline reports are beginning to pick up as fishing increases this summer. Striped bass fishing has been superb and many people have been chumming for them. Unfortunately, chumming in warm weather can produce high mortality of catch and release fish if circle hooks are not used and careful catch and release techniques are not practiced. Hotline reports of floating dead stripers have come in from all areas of the Bay. Fisheries Service has assisted the Department of Environment in investigation of three reports of probable chumming related kills.

Reports of striped bass with anomalies ranging from red spots to sores have been increasing. Regional scientists have recently met to discuss this issue, and DNR is leading an investigation into possible causes. Scientists agree that the anomalies are not Pfiesteria. Check out the separate fact sheet on striped bass.

Rapid Response Teams
Rapid response teams have investigated several incidents. A potential fish kill in the Potomac was found to be the result of discards from a commercial fish net; and diseased catfish in the creel of a sport fisherman in the Nanticoke was found to be an isolated instance after trawl and seine sampling were conducted in the same area.

The Pfiesteria team responded to the Pocomoke river in the area of Williams Point in late June after a person was reported to have become mildly sick after being on the river. Fish, Pfiesteria and water quality samples were taken at three sites near Williams Point. Trawl, electroshock and cast net samples on June 16, 23 and 24 found no indication of problems. In addition, University of Maryland has started baseline studies on cage effects of white perch held in the Pocomoke. In white perch experiments June 24 through June 29, they found no fish disease problems that could related to Pfiesteria.

Water for Pfiesteria analysis was collected from three sites in the lower Pocomoke River on June 25. Analysis by North Carolina State University found no Pfiesteria-like cells in two of the samples and very low levels of possible Pfiesteria-like cells in the third sample. Densities of the possible Pfiesteria-like cells in the one sample are approximately 1/5 of that necessary to result in lesions in fish. They were no fish health problems observed in association with the water collections. Based on the low densities of cells in the sample and the lack of fish health problems, no further analysis of the organisms in the water samples is planned. DNR continues to monitor for any changes to fish health and water quality in the Pocomoke.

Water and Habitat Quality
Field Efforts The following systems have been recently sampled:

Systems affected by Pfiesteria last year:

  • Pocomoke: 6/15, 7/16
  • Chicamacomico: 6/15, 6/18, 7/23
  • Manokin/Kings Creek: 6/15, 6/22, 7/9

Expanded Pfiesteria monitoring activities:

  • Big Annemessex: 6/16, 6/24
  • Nanticoke: 6/16, 6/25
  • St. Martin River: 6/29
  • Newport Bay/Trappe Creek: 6/29, 6/30
  • Wicomico: 7/1, 7/9

Water samples are taken to measure common water quality parameters, such as salinity and dissolved oxygen. Specialized samples are also periodically taken to measure nutrients (such as nitrogen and phosphorus) and the amount and type of algae in the water.

Additional Pocomoke River monitoring
In addition to standard water quality measurements, samples will be collected July 16 on the Pocomoke River for urea and zooplankton analysis. Urea is one component or "dissolved organic nitrogen", a type of nutrient that was found in high concentrations on all the affected rivers in 1997. Urea is not typically sampled for, but recent research suggests that it may influence the growth of dinoflagellates. DNR is working with researchers at University of Maryland to evaluate the relationship between urea concentrations in the water and Pfiesteria activity.

Zooplankton (very small animals that feed on algae) will also be collected from a targeted location on the river. Information on zooplankton community composition will be used to provide background information about these populations, and to supplement the information we are gathering on the algal populations in Shelltown area.

Habitat Quality Update
Salinity on all rivers during June remained well below values typically observed during this time of year, with record lows being measured on the Manokin River. Other physical parameters (temperature, dissolved oxygen, pH) were generally similar to previous years' values. Nutrient and chlorophyll (algae) results are now back from the laboratories for cruises taken during March and April, and some preliminary information is back for samples collected during May. Comparison of nutrient concentrations at long-term monitoring sites on these rivers to previous years' values revealed that nutrient levels in March-May 1998 were generally similar to 1995-1997 averages for the same months. Chlorophyll (algae) concentrations during April 1998 were similar to April 1995-1997 values on all of the systems. May 1998 algal results are not yet back from the laboratory.

Nutrient and algal comparisons are not possible for the St. Martin and Trappe Creek because long-term historic data does not exist for coastal bay tributaries.

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