Algae-produced toxin found to be cause of Middle River fish kill


Jay Apperson

(410) 537-3003

Algae-produced toxin found to be cause of Middle River fish kill

Baltimore, MD (December 7, 2015) – A fish kill last month in the Middle River area of Baltimore County was caused by toxins produced by algae, a Maryland Department of the Environment investigation has found.

Laboratory testing confirmed the presence of toxins that are produced by the dinoflaggelate algae Karlodinium veneficum in water samples collected in the area of the fish kill. Earlier testing had shown the presence of the algae in the waters with cell counts high enough to produce damaging levels of toxin. In addition, an examination of fish tissue showed physical damage to gill tissue that is consistent with the known effects of the algae-produced toxins.

The investigation also showed higher than normal natural estuarine salinity levels in the upper areas of the Middle River and its tributaries. Such conditions can affect the physiology of fish and are believed to be a factor in triggering the algae bloom and causing the fish kill.

After becoming aware of citizens’ concerns about possible discharges into the waters in the area of the fish kill the Department began an investigation of those concerns. The investigation has included multiple inspections of business facilities in the area and testing of water samples from an outfall there. The Department has found no evidence of any chemical pollution as a cause of the fish kill.

“The Maryland Department of the Environment has aggressively investigated all aspects of this fish kill, following the science every step of the way,” said Maryland Secretary of the Environment Ben Grumbles. “We know anglers and other citizens are concerned about this, and we appreciate their assistance in raising attention to this issue through social media. We’re concerned too. A fish kill sends a strong signal that something is very wrong, and it underscores the importance of clean water to our economy and our quality of life. We will work in collaboration with Baltimore County and its citizens to reduce the nutrient pollution that can help cause algae blooms.”

The Department currently estimates that up to 200,000 fish were killed in the Upper Middle River and tributaries that include Cow Pens Creek, Norman Creek, Frog Mortar Creek, Hopkins Creek and Dark Head Creek. The fish affected include largemouth bass, yellow perch, bluegills, crappies, chain pickerel, pumpkinseed sunfish, carp, killifish, Atlantic menhaden, spottail shiner and gizzard shad.

The Department will prepare a written, technical report on the fish kill and the investigatory findings.


Fish kill investigation overview

The Department of the Environment’s Science Services Administration is responsible for investigating fish kills in Maryland. Department biologists with 50 years combined experience investigating fish kills investigated the Middle River fish kill. During the investigation the Department has provided information to the Maryland Department of Natural Resources and the Baltimore County Health Department.

The Department first received reports of the fish kill on November 9. Department fish kill biologists have made at least five visits to the site, with several additional visits from inspectors from the Department’s compliance programs. Biologists collected water samples and retrieved basic water quality information from Norman Creek, Hopkins Creek, Frog Mortar Creek, Dark Head Creek and Cow Pens Creek. Investigators also collected live fish from Cow Pens, Hopkins and Frog Mortar creeks for microscopic examination.

On November 13, the Department announced that the preliminary results of the investigation showed the cause of the fish kill to be a strain of algae, Karlodinium veneficum, that produces toxins that are lethal to fish.  While blooms of this type are typically seen in summer months, warm weather in the fall might have allowed the algae to survive and grow. A drop in water temperature is suspected to have caused the algae to die, and the rapid die-off of the algae resulted in a release of toxin.

After becoming aware of citizens’ concerns about possible discharges in the area, the Department’s compliance programs launched an investigation.

The Department’s finding that the fish kill was caused by toxins produced by algae is supported by the following factors:

  • An analysis of water samples taken in the days after the fish kill showed the presence of Karlodinium veneficum  in cell counts high enough to produce dangerous levels of toxins that kill fish by inhibiting oxygen uptake through their gills.
  • Microscopic examination of fish organ tissue showed extensive physical damage to gills.
  • The investigation has not shown any link between activities at area business facilities and the fish kill. Test results of water samples from an outfall to Cow Pens Creek did not show any evidence of contaminants capable of causing a fish kill of this magnitude.
  • Based on the Department’s experience and expertise, it would be highly unlikely, if not impossible, for a point source to be the cause of a fish kill that appears to have taken place in a short period of time in an expansive area of water. Evidence shows that the fish were killed almost simultaneously, and the Department estimates 16 miles of shoreline in a tidal-controlled estuarine environment were affected by this fish kill.
  • Natural estuarine salinity levels increased as much as four-fold, compared to the summer, in the upper areas of the Middle River and its tributaries. Such conditions are conducive for Karlodinium veneficum algae to bloom. In addition, the salinity level was high enough to affect the physiology of freshwater fish.  Salinity levels can be affected by lack of freshwater flow from major regional tributaries.
  • Laboratory testing results confirmed the presence of harmful levels of toxins that are produced by Karlodinium veneficum in a sample collected in Hopkins Creek shortly after the fish kill.


Testing for algae toxin

The Department provided water samples to the Institute of Marine and Environmental Technology for testing for the presence of algal toxins.  The testing was conducted by Allen Place, Ph.D., a professor at the University of Maryland Center for Environmental Science and biochemist who is an expert on toxic algae and harmful algal blooms. The test results showed the presence of Karlotoxins in levels sufficient to cause gill damage.


Fish tissue examination

The National Oceanic and Atmospheric Administration and Maryland Department of Natural Resources Cooperative Oxford Lab conducted microscopic examination of organs from fish collected from the upper Middle River, Cow Pens Creek and Frog Mortar Creek. That examination found extensive damage to gills, indicating an acute irritant and quick death, along with a stressor consistent with respiratory impairment – all of which is consistent with the effects of Karlotoxins.


Tilley Chemical

The Department’s compliance programs conducted multiple inspections of Tilley Chemical, a commercial product supplier and repackager located on Martin Boulevard in an area that drains to Cow Pens Creek. The inspections did not reveal any evidence of a recent chemical spill.

The Department’s Water Management Administration collected samples from a stormwater collection system from the Tilley property and surrounding areas, including an outfall pipe. Laboratory test results of water samples taken from this outfall show trace levels of organic contaminants and petroleum hydrocarbons, both of which are typically seen in runoff from parking lots.

The Department’s Land Management Administration conducted a hazardous waste inspection of Tilley Chemical. The Department will continue to evaluate aspects of the facility’s operation, particularly vehicle and rail car washing and product transfer activities, to ensure that adequate spill prevention procedures are in place.

The compliance programs’ investigations are continuing.


Lockheed Martin Corporation

The Department reviewed Lockheed Martin Corporation’s ongoing remediation activities at its Middle River complex. The Department oversees these activities through the authority of a consent order. The Department reviewed stormwater management controls at the site, and no violations were noted. Additionally, Lockheed Martin routinely collects water quality samples for an assortment of potential surface water contaminants. Lockheed Martin has provided to the Department preliminary test result information for samples collected after the fish kill. That preliminary information, as well as historical water quality data, shows no levels of contamination capable of causing a fish kill.


Fish kills in Maryland

The Middle River fish kill appears to be the largest in Maryland this year. The Department revised its initial estimate of the number of fish killed in the upper Middle River and several of its tributaries to up to 200,000 after investigators went to additional areas and observed dead fish.

There have been about 80 smaller fish kills this year in Maryland, caused by factors such as low dissolved oxygen levels in water, localized pollution and the discarding of dead fish. This is the second Karlodinium-induced fish kill this year and the 37th confirmed in the state since 2002. The Department investigates an average of about 100 fish kills a year. The size of fish kills varies widely. There have been 55 fish kills of 100,000 or more since Maryland began investigating fish kills in 1984.

Excessive levels of nutrients such as nitrogen and phosphorus in the water can lead to algae blooms. Reducing nitrogen and phosphorus pollution from all sources is at the heart of Maryland’s blueprint for Chesapeake Bay restoration.

Anyone with information on fish kills or with other concerns on environmental matters involving the Chesapeake Bay or its tributaries should call the Bay environmental hotline at 877-224-7229.