July 10, 2007
Contact: Jim Erickson, (734) 647-1842, ericksn@umich.edu
U-M-led study concludes that current
rules to
protect Great Lakes from ship-borne
organisms
are inadequate; stronger measures advocated
ANN ARBOR, Mich.---
Current rules aimed at minimizing the number of nonnative species that
hitchhike
into the Great Lakes on oceangoing ships are inadequate and often
impractical,
a University of Michigan
researcher and colleagues from five other U.S. and Canadian
institutions have
concluded.
The authors of a three-year study
recommend that
"saltwater flushing," the practice of rinsing a ship's ballast
tanks with deep-ocean water before it
enters the St. Lawrence Seaway, be added to a set of requirements
called the
Code of Best Practices for Ballast Water Management. In 2002, the St.
Lawrence
Seaway corporations in the United States
and Canada
adopted rules making compliance with the code mandatory for entry into
the
seaway.
The study, released July 10, focuses on
so-called NOBOB (no
ballast on board) ships, those that carry no pumpable water in their
ballast
tanks. More than 90 percent of the cargo ships entering the Great Lakes
through
the St. Lawrence Seaway are NOBOBs,
and nonnative organisms can lurk in the residual water and
sediment left in the mostly empty ballast tanks.
Various approaches for sanitizing
ballast water – using
chemicals, heat, ozone or ultraviolet radiation, for example – are
being
explored but have not yet been adopted. In the interim, saltwater
flushing provides
an inexpensive alternative that would likely kill most of the lingering
freshwater organisms in NOBOB ballast tanks, said U-M nutrient chemist
Thomas
Johengen, one of the study's co-leaders.
"We think that saltwater exposure is an
effective way
to protect freshwater systems. If we could apply it in every NOBOB, we
think
that we can close a loophole," said Johengen, an assistant research
scientist at U-M's School
of Natural Resources
and
Environment.
Johengen and project co-leader David
Reid of the Ann
Arbor-based Great Lakes Environmental Research Laboratory (GLERL)
worked with
scientists from the University
of Windsor, Old Dominion University,
the Smithsonian Environmental Research Lab, and Jenkins &
Associates Ltd.
GLERL is part of the U.S. National Oceanic and Atmospheric
Administration.
The report, "Identifying, Verifying and
Establishing
Options for Best Management Practices for NOBOB Vessels," was funded by
the Great Lakes Protection Fund, with additional support provided by
the U.S.
Coast Guard and NOAA. Known informally as NOBOB-B, the study is a
follow-up to
another report (NOBOB-A) the same research team released two years ago.
NOBOB ships are loaded to capacity with
cargo and carry no
declarable ballast water on board. But once they unload their cargo,
they take
on tons of Great Lakes water for
stability. If
they then load cargo at another Great Lakes port, they must discharge
the
ballast water, which is now a mix of Great Lakes
water, residual foreign water and sediment -- as well as stowaway
organisms
that can range from pathogenic microbes to mollusks and fish.
At least 185 nonnative aquatic species
have been identified
in the Great Lakes, and ballast water
is
blamed for the introduction of about 60 percent of them, Johengen said.
The invaders include the notorious
zebra mussel, a small but
aggressive Eurasian fish called the river ruffe, and two types of goby.
Viral
hemorrhagic septicemia, which caused a huge Great
Lakes
fish kill last year, may have arrived in transoceanic ships as well.
The latest NOBOB study included more
than 70
salinity-tolerance experiments designed to mimic saltwater flushing of
ballast
tanks and its effects on various invertebrates – including larval
stages of the
zebra and quagga mussels. The tests were conducted in Lake Erie, Lake
Michigan,
Chesapeake Bay, San
Francisco Bay
and several European
ports.
The experiments showed that many
organisms originating in low-salinity
ports can be quickly eradicated from ballast water through exposure to
full-strength seawater.
"One of the key findings here has been
to confirm that
saltwater can be quite effective at reducing the risk of invasions from
ballast
water," Reid said. "It's not 100 percent effective against all types
of organisms, but it's far better than what's been going on, which has
been basically
no regulation at all for NOBOBs."
The study also evaluated the
effectiveness of the current
Code of Best Practices for Ballast Water Management.
The code requires vessels entering the Great Lakes to apply a "precautionary approach"
that includes
minimizing ballast water uptakes at ports where toxic algal blooms,
known
populations of harmful aquatic organisms and pathogens, sewage
outfalls, or
dredging activities are present.
The team concluded that the real-world
constraints of cargo
loading and unloading often make it impractical for crews to carry out
the environmental
precautions. In addition, the precautionary measures "require
information
on local water quality conditions that is not generally available to
the
shipping industry," the researchers determined.
In 2005, the U.S. Coast Guard issued a
policy statement
encouraging mid-ocean ballast tank flushing. Last year, Canada adopted management regulations
requiring
that ballast water – including residual water in NOBOBS – be treated
with saltwater
or salt – before the water is discharged in the Great
Lakes.
"This report is actually providing,
finally, the basis
of support for why the Canadians did what they did," Reid said.
"We've been keeping the regulatory agencies apprised of our results all
along, and they (Canadian officials) actually jumped on it before we
were
completely finished."
Nearly 2,000 oceangoing vessels
conducted Great Lakes trade
via the St. Lawrence Seaway between
1999 and
2006, according to the St. Lawrence Seaway Development Corp.
Links:
Read the final NOBOB-B report: http://www.glerl.noaa.gov/res/Task_rpts/2004/aisreid04-1.html
U-M School of Natural Resources and
Environment: http://www.snre.umich.edu/
Great Lakes
Environmental
Research Laboratory: http://www.glerl.noaa.gov/
# # # # # #
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--
Jim Erickson
News Service
University of Michigan
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Ann Arbor, MI 48109-1399
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