the health and habits of Crabbing requires fishers to spend hours Hans Paerl (left) samples an IMS mesocosm with 



in fish-kill areas. on the water placing and pulling pots. Matt Fitzpatrkk, a former technician. They are studying 



how algae respond to the addition of nutrients. 



Human Health Effects 



In one study, a team of ECU 

 researchers compared the health and 

 habits of crabbers to those of a group of 

 nonfishers. The team also examined 

 where crabbers set their pots and where 

 fish kills, algal blooms and other water 

 quality problems have taken place. 



The researchers concluded that 

 casual contact with eastern North 

 Carolina waters under normal conditions 

 — in the absence of fish kills, algal 

 blooms, red tides or other indicators of 

 poor water quality — poses extremely 

 low health risks. Reports of ill-health 



effects caused by high concentrations of 

 Pfiesteria-Wke organisms during fish 

 kills appear to have been "greatly 

 exaggerated," says David Griffith, the 

 ECU anthropologist who headed the 

 research team. 



Griffith notes that North Carolina 

 has water quality problems, but his 

 research did not find a link between 

 poor water quality and bad health. 



"The threat is exaggerated for the 

 human population. But I can't speak for 

 fish," Griffith says. "This is a very 

 narrow kind of finding that people who 

 work all day on the water for their entire 



lives are not sick just because of that." 



In 1996, the researchers inter- 

 viewed 253 crabbers who worked in the 

 Neuse and Pamlico rivers and in the 

 southern sections of the Pamlico Sound 

 (Pamlico crabbers). They compared the 

 crabbers' replies to questions about their 

 recent health to responses from two 

 control groups: 1 15 crabbers working in 

 Albemarle and Currituck sounds, the 

 Alligator River and northern areas of the 

 Pamlico Sound (Albemarle crabbers) 

 and 125 nonfishers living in the 

 crabbers' communities. 



Continued 



- Devastating to Aquaculture 



Heterosigma 



Chocolate-brown waters are 

 a sign that Heterosigma carterae is 

 blooming. To aquaculturists on the 

 West Coast, these brown waters 

 forewarn a loss of green in their 

 pockets. 



The Heterosigma toxic algae has 

 been reported on every continent 

 except Antarctica, and it has 

 caused multimillion-dollar fish kills 

 worldwide, says Rose Ann 

 Cattolico, a Washington Sea Grant 

 research scientist. 



Sea bream, salmon, yellowtail, 

 sea bass, trout and flounder have 

 been killed by Heterosigma blooms. 

 In the Pacific Northwest salmon 



industry, losses have reached more than 

 $20 million over the past eight years, 

 and Japan estimates that Heterosigma 

 has cost its aquaculture industry more 

 than $2 billion over a 1 6-year period. 



Beyond this economic havoc, the 

 ecosystem suffers as well. "You don't 

 have to have lots of dead fish in the 

 water in order to have an effect on your 

 ecosystem," Cattolico says. "There are 

 many impacts on many organisms and 

 at different levels." 



Specifically, Heterosigma blooms can 

 interfere with the survival and reproduc- 

 tion of invertebrates. When juvenile 

 oysters or clams are fed Heterosigma, 

 their growth rates are 20 percent lower 



than those of shellfish fed 

 Skeietonema costatum (healthy food 

 for oysters). Adult shellfish are not 

 directly affected by Heterosigma, but 

 oysters refuse to feed when this 

 toxic algae is in the water. 



"And if they aren't feeding, 

 they're not surviving with the same 

 success rate," Cattolico says. 



Likewise, sea urchin eggs will 

 not grow at all in water where 

 Heterosigma is present. For aquacul- 

 turists who cater to Asian markets 

 where people covet sea urchins as a 

 meal, Heterosigma can be a devastat- 

 ing setback to business. E 



-J.F.N. 



COASTWATCH 17 



