SOLVING THE MYSTERY 

 OF PFIESTERIA 



A scientist in Greensboro probes for ways to track the toxic microscopic organism. 



By Daun Daemon • Photographs by Herman Lankford 



The 



I he suspect is elusive, a 

 master of masquerade, a shape 

 shifter capable of changing 

 guises almost at a moment's 

 notice. Although its identity 

 has been known since 1991, 

 understanding what makes it 

 tick has proven a laborious 

 task. 



On the job are a number of 

 persistent sleuths, all sniffing 

 out clues that will help crack 

 the case. With diligent effort, 

 they sift through evidence, 

 track down leads, put the 

 squeeze on people who might 

 have a tidbit of promising 

 information, and work long 

 hours making sense of it all. 



Instead of trenchcoats and 

 natty hats, though, these 

 detectives wear blue jeans and 

 lab coats. And the suspect they 

 hope to detain isn't an under- 

 world thug or a drug kingpin 

 — it's a one-celled creature 

 called Pfiesteria piscicida, 

 which has been linked to more 

 than 50 percent of the fish kills 

 in North Carolina coastal 

 waters in recent years. 



One of the intrepid 

 gumshoes on the case is Parke 

 Rublee, an associate professor of 

 biology at the University of North 

 Carolina at Greensboro and a Sea 

 Grant scientist. Rublee is developing 

 a probe that will uncover the toxic 

 dinoflagellate where it lurks in the 

 environment. 



Taking a break from examining 

 Pfiesteria cells under a microscope 



His quest is not as easy as it 

 sounds because, as Rublee says, 

 "there's always a new surprise with 

 Pfiesteria. 



"It's not necessarily unpredictable 



— as scientists we presume that we 

 will know enough to be able to predict 



— but right now we don't know 



enough about this organism. 

 We just don't know what the 

 rules are." 



What Rublee and his 

 colleagues working on the 

 enigmatic organism do know is 

 that Pfiesteria is one of a kind, 

 different from its red tide 

 relatives in several ways. 



Unlike red tide dinoflagel- 

 lates, Pfiesteria does not signal 

 its presence in the water. It lies 

 in bottom sediments in a cyst 

 stage until it senses approach- 

 ing fish. It then transforms into 

 a zoospore with a whiplike 

 appendage, swims into the 

 water column and releases 

 toxins that directly or indi- 

 rectly cause fish to slough their 

 skin. The zoospore consumes 

 pieces of the tissue and 

 reproduces. 



Pfiesteria neurotoxins also 

 affect a fish's nervous system, 

 causing the animal to become 

 disoriented and lethargic and to 

 struggle for air at the water's 

 surface. With its breathing 

 mechanism paralyzed, the fish 

 will suffocate if it cannot 

 escape. 



As fish die, the dinoflagellate 

 transforms back into a cyst within 

 minutes to hours and sinks once again 

 into the sediments. 



Perhaps most vexing for those 

 studying Pfiesteria is its ability to 

 disguise itself. Scientists have identi- 



Con tinned 



COASTWATCH 5 



