Herwig says with a wry grin. "After that comes 

 many hours spent processing samples and 

 sorting those tiny planktonic organisms by genus 

 and species." 



While sorting the plankton, the researchers 

 seek to distinguish foreign species from those 

 native to North America's West Coast waters. 

 They also try to recognize species associated 



Legislatures in California, Hawaii, 

 Maryland, Oregon and Virginia have enacted 

 similar laws. Though not legislated in North 

 Carolina, Erik Stromberg, North Carolina Ports 

 Authority executive director, spearheaded efforts 

 in 1998 to ensure that vessels en route to state 

 ports engage in ballast water exchange before 

 entering the U.S. Exclusive Economic Zone. 



TOP: Sinocalanus doerri, an Asian planktonic copepod — first appeared in San Francisco Bay in 

 1978 and in the Columbia River estuary in 2002 — and is thought to have been introduced into these 

 environments by ballast water. BOTTOM: Tallying samples to determine how the ozone system is 

 working. RIGHT: A keypad identifies which forms of zooplankton are "live," "dead" or "moribund." 



with coastal and open ocean habitats. 



That latter distinction is especially valuable 

 in gauging the effectiveness of what scientists 

 call mid-oceanic exchange — an international 

 voluntary ballast water management measure. 



To reduce the possibility of introducing 

 exotic aquatic organisms, the Washington State 

 Legislature recently approved a bill requiring 

 transoceanic vessels to empty and refill their 

 ballast tanks in the open ocean. Vessels entering 

 U.S. ports are required to report these activities 

 to the U.S. Coast Guard. 



Ballast water exchange on the high seas 

 greatly reduces the chances of ships ferrying 

 planktonic aquatic organisms from one 

 nearshore area to another. 



Alas, seawater swapping is probably not 

 sufficient to eliminate the threats from ballast 

 water releases. The designs of most ballast tanks 

 make it difficult to drain every drop of water or 

 replace all of the living organisms in a ballast 

 tank, says Herwig. Sediments also may 

 accumulate in the nooks and crannies of a ballast 

 tank. Living organisms and resting stages of 



organisms may accumulate in the sediments. 



Furthermore, Washington's ballast water 

 regulation has a loophole. A ship's crew can be 

 exempted from making mid-ocean exchanges if 

 stormy seas or other conditions would present 

 insurmountable safety hazards. 



FINE-TUNING AND 

 TEAM-BUILDING 



Ozone treatment may sound great in 

 principle, but there's still work to be done. 

 That's because the extended life of bromine can 

 raise environmental concern. Ozone's quick 

 decay rate means it is unlikely to threaten native 

 life when the ballast water is poured out. 



Longer-lived bromine, however, still may 

 be present in the released water, so scientists 

 must make sure that bromine will not harm the 

 aquatic systems into which it is released. For this 

 reason, researchers are trying to pin down the 

 lowest concentration of ozone that will get the 

 job done. 



Lower concentrations of ozone also will 

 reduce operational costs — an important 

 consideration in getting the shipping industry to 

 adopt this technology. The Totisina's formidable 

 network of stainless steel pipes almost certainly 

 would be too expensive for most ships to install, 

 so the experimenters also are exploring a less 

 costly alternative system. 



Instead of bubbling ozone gas through a 

 maze of tubes for the entire voyage, the new 

 streamlined set-up simply will inject ozone into 

 the seawater on its way to the ship's ballast 

 tanks. 



Herwig suspects that employing a 

 combination of ballast water treatment 

 technologies — ozone, ultra-violet light, 

 chemical additives and fine-meshed filters — 

 ultimately may be the best way to tackle the 

 invasive species problem. Perhaps different 

 technologies will be appropriate for different 

 types of vessels, he suggests. There also may be 

 sequential treatments developed. 



Many researchers, says Herwig, believe 

 that a filtration step could be used first to remove 

 larger organisms and then a second step, perhaps 

 ozone treatment, would follow to remove the 

 smaller life. For now, though, there is no 

 consensus about which methods are most likely 

 to pay off. 



10 HOLIDAY 2003 



