GOVERNMENT AFFAIRS BoatU.S. SPECIAL REPORT BY MICHAEL VATALARO
THE ARMS RACE AGAINST INVASIVES
Invasive species often become a nuisance to boaters because they proliferate greatly in the absence
of natural checks and balances. Now researchers are fighting back with solutions found in nature
ZEBRA MUSSELS, and their close cousins quagga mussels, are xceptional at what they do for a living: filter phytoplankton from the water to feed on. This simple act, which happens at the rate of around a quart of water a day per mussel, can dramatically improve water clarity. But at the same time, these invaders, which
hitched a ride in the belly of an oceangoing ship from Europe, are also reducing
the food supply for the fish and native mussels that ordinarily rely on it. The
small bait fish that feed on phytoplankton in turn are food for predatory salmon,
bait population declines, their numbers go down as well.
In the meantime, with a single female zebra mussel capable of
releasing one million eggs a year, the little mollusk is taking over. Since being discovered
in the Great Lakes in 1988, these pests have made their way into freshwater lakes and
river systems in dozens of states, forcing power plants, canal and lock operators, and
municipalities to spend billions of dollars in control costs when the rapidly reproducing
mussels clog up water intakes or machinery.
Happy to adhere to any hard surface, such as hulls, running gear, or culverts, mussels
must be physically scraped off, or poisoned with chlorine in the case of water intakes,
which is also toxic to most other forms of life in the water. The Great Lakes states alone
spend $100 to $400 million each year on control efforts. An estimate of costs associated
with setting up chemical control systems at one large municipal water facility ranged
from $2 - $4 million in initial costs with $500,000 to $850,000 per year to be spent on
chemicals. But now, researchers have come up with a way to use the mussel’s extraordinary
filtering abilities against it, which for the first
time could provide a means for large-scale
eradication without collateral damage, and
cost reductions.
THE SILVER BULLET
For more than a decade, researcher Dan
Molloy at the New York State Museum
Cambridge Field Lab has been investigating a natural toxin that is deadly to zebra
and quagga mussels, but doesn’t harm fish,
vegetation, or other wildlife. A strain of
the bacteria Pseudomonas fluorescens, when
ingested by a mussel through filter feeding,
kills it within a week. The bacteria doesn’t
even have to be alive — it doesn’t infect the
mussel with a disease. The dead bacterial
cells themselves are the toxin. What’s more,
this toxin is incredibly specific to zebra
and quagga mussels. Native mussels aren’t
harmed when exposed.
After two years of field tests in Colorado
and Ontario, where treatments averaged 70
percent mortality rates, the Environmental
Protection Agency (EPA) granted approval
to a commercialized version of the toxin
Water hyacinth, an invasive plant from the Amazon, chokes off access to transient slips in Stockton, California.
