neurotoxin and feeding on more fish. It's 

 a horrific feeding frenzy even Stephen 

 King couldn't imagine. The final result 

 is a mass of floating dead fish. 



To escape these microscopic 

 monsters, fish and crabs often try to 

 leave the water. Fishermen call these 

 occurrences "fish walks" or "crab 

 walks." 



Those fish that do escape often 

 don't live long. They carry too many 

 battle scars — open, bleeding sores or 

 holes eaten through their bodies that 

 make them susceptible to other patho- 

 gens and bacteria, Noga says. 



After the fish die, the killer 

 dinoflagellate can make one of several 

 transformations. It can encyst and settle 

 to the bottom in a deceitful resting stage, 

 Burkholder says. Or it can shed its 

 flagella and become a nontoxic amoeba. 

 Amoebas, shape-shifting multiarmed 

 single cells, continue to leisurely feed on 

 the fish carcass and other proteins in the 

 water column or on the bottom. 



Or the dinoflagellate can transform 

 into asexual, nontoxic zoospores that 

 swim in the water column and are 

 attracted to areas rich in algae and 

 nutrients, particularly phosphorus. 



Because of its unusual transforma- 

 tions, some scientists and resource 

 managers have doubted Burkholder 1 s 

 findings. But Karen Steidinger, a 

 phytoplanktonologist with the Florida 

 Department of Environmental Research 

 and the Florida Marine Research 

 Institute, says this dinoflagellate is for 

 real. 



"It is a very cryptic species, one that 

 is difficult to identify because of the 

 small size of the flagellated stages and 

 its life cycle," Steidinger says. "Its 

 amoeboid and cystlike transformations 

 are life stages that most marine phyto- 

 planktonologists would not associate 

 with that of a dinoflagellate." 



But no matter what it becomes — 

 cyst, amoeba or zoospore — it can 

 transform back into a killer, sometimes 

 within minutes, in the presence of a 

 school of fish. 



Once they were able to identify the 

 killer dinoflagellate, Burkholder and 

 Noga documented its presence at fish 



kills in North Carolina and along the 

 East Coast. 



But was the toxic dinoflagellate a 

 new organism, or had it been in our 

 estuaries all along and never been iden- 

 tified? Burkholder believes it's the lat- 

 ter. Being such a primitive life-form, the 

 dinoflagellate has probably existed for 

 eons undetected. But Burkholder be- 

 lieves its abundance and visible effects 

 — fish kills — may have increased in 

 the last 50 to 75 years as the water qual- 

 ity in our estuaries has degraded be- 

 cause of increased agricultural and com- 

 mercial development. 



JoAnn Burkholder 



In her NCSU laboratory, Burk- 

 holder tested 28 species of fish for sus- 

 ceptibility to the toxic dinoflagellate. 

 None were immune to the toxin, al- 

 though some species were more sensi- 

 tive than others. Blue crabs, clams, scal- 

 lops and young oysters are also affected 

 by the toxin. She has yet to test shrimp 

 or adult oysters. 



Are there any human effects from 

 this waterborne killer? 



There are no certain instances of 

 the dinoflagellate affecting fishermen, 

 swimmers or boaters on the water. 



But problems have occurred in 

 Burkholder' s laboratory where lab 

 assistants and technicians have had 

 prolonged and direct exposures to the 



dinoflagellate in its active, toxin- 

 emitting phase. One of Burkholder' s 

 research associates was hospitalized 

 after experiencing memory loss, 

 disorientation and speech impediments. 

 Burkholder, too, has suffered memory 

 loss and disorientation. 



Until the toxin is fully character- 

 ized by chemists, however, neither 

 Burkholder' s nor her research 

 associate's problems can be fully 

 understood. The N.C. Department of 

 Health is investigating the human 

 effects of this dinoflagellate, but results 

 may be more than a year away. 



For now, Burkholder has these 

 cautions for people who work and play 

 on the water. 



• Leave an area where fish are 

 floating at the water's surface. A fish 

 kill may be in progress, and the 

 neurotoxins may be in the water and air. 



• If you dip your hands or feet in 

 an area where the dinoflagellate 



is active, immediately wash them with a 

 10 percent bleach solution. Bleach 

 detoxifies and kills the dinoflagellate, 

 Burkholder says. 



• If you're a recreational fisherman, 

 don't keep or eat fish that have visible 

 sores or holes in the flesh. 



• Don't eat fish that have washed 

 ashore or beached themselves. 



Consumers of seafood bought at 

 retail outlets such as grocery stores, 

 seafood markets and restaurants should 

 not worry. Commercial fishermen 

 would not harvest fish affected by the 

 dinoflagellate because the unsightly 

 sores make the fish unfit to sell. 



To help researchers such as 

 Burkholder and Noga learn more about 

 this mysterious dinoflagellate, commer- 

 cial fishermen and recreational water 

 users are asked to report any fish kill 

 they spot. Note the area where the fish 

 are floating as exactly as possible, then 

 leave. Do not take fish or water samples. 

 Quickly call either the N.C. Division of 

 Marine Fisheries at 1-800/682-2632, 

 Burkholder' s NCSU laboratory at 

 919/515-2726 or 919/515-3421 or 

 Noga's NCSU School of Veterinary 

 Medicine laboratory at 919/829-4393 

 or 919/829-4236. E 



20 JULY/AUGUST 1994 



