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Ballast Water Facts
- Ships take in a certain amount of water for stability and trim
before a voyage. Once the ship arrives at its destination, it
may release this ballast water into the destination harbor. Ballast
stabilizes ships in the water and is a necessary feature of commercial
shipping. Ballast is primarily composed of water and is full of
stones, sediment, and thousands of living species. International
shipping industries are responsible for the majority of these
alien species invading foreign waters.(1)
- Over 3,000 marine species travel around the world in ships’
ballast water on a daily basis. These organisms range in size
from microscopic bacteria to large plants and free-swimming fish.(1)
- Estimates are that ships pump more than 21 billion tons of
ballast into U.S. waters every year; that is, 40,000 gallons a
minute or nearly 700 gallons a second.(2)
- A modern cargo ship can carry from 100,000 to 10,000,000 gallons
or more of ballast water.(2)
Open Sea Exchange
Presently, ballast water exchange is the only effective management
tool to reduce the risk of ballast-mediated invasion. Ballast water
exchange involves replacing coastal water with open-ocean water
during a voyage. This process reduces the density of coastal organisms
in ballast tanks that may be able to invade a recipient port by
replacing them with oceanic organisms with a lower probability of
survival in near-shore waters. Ballast water exchange is recommended
as a voluntary measure by the International Maritime Organization
Impacts of Some of the Worst
Invasive Aquatic Species
Photo courtesy of Argonne National Laboratory,
a U.S. Department of Energy laboratory
Cholera is an acute intestinal infection caused
by the bacterium Vibrio cholerae.
It has a short incubation period, from less than one day to
five days, and produces an enterotoxin that causes a copious,
painless, watery diarrhea that can quickly lead to severe
dehydration and death if treatment is not promptly given.
Vomiting also occurs in most patients.
From polluted harbors and bays, ship ballast
can carry the Vibrio cholera,
concealed in plankton, to estuaries around the world. The
virulent El Tor cholera strain, which causes intestinal disease
with symptoms of severe diarrhea, was probably carried by
ballast water from Asia to Latin America in 1991, and then
spread to Mobile Bay, Alabama, where it was found in oysters
in closed shellfish beds.(4)
Photo courtesy of U.S. Fish & Wildlife
Non-indigenous, landlocked alewives impact
native ecosystems in a number of ways. They alter the zooplankton
community, out-compete other fish species for food, feed on
the eggs and larvae of other fish, and cause both reproductive
failure in trout and salmon and declines in native species.
For example, the disappearance of native Lake Ontario planktivores
such as whitefish and lake herring has been attributed to
the introduction of alewives which reduced zooplankton populations.
In addition, alewives undergo periodic mass
mortalities. When these large-scale die-offs occur, several
problems arise. First, any predator fish that utilizes alewife
populations as a main source of food will have difficulty
finding enough to eat. This results is poor growth rates or
declines in game fish such as chinook, coho, brown trout,
and lake trout populations in the Great Lakes. Second, the
large numbers of alewives that die in these events wash up
on beaches, causing foul odors and public health concerns.
Stretches of shoreline in the Great Lakes are often closed
for weeks at a time after an alewife die-off so that the thousands
of fish can be bull-dozed off the beaches, as is often necessary.(5)
Photo courtesy of Minnesota Sea Grant
Ruffe pose a threat to native fish because
they mature quickly, have a high reproductive capacity, and
easily adapt to new environments. Ruffe are more tolerant
of poor water conditions and have several anatomical features
that give them an advantage over native fishes. Native fish
populations – especially yellow perch, emerald and spottail
shiners, trout perch, and brown bullhead – have declined
in locations where ruffe have become established.
Ruffe were first detected in western Lake
Superior in 1986. The ruffe population has increased rapidly
in the St. Louis River at Duluth-Superior and has spread to
other rivers and bays along the south shore or western Lake
Superior. They have also spread past the Ontonagon River in
the Upper Peninsula of Michigan. They are now one of the most
abundant fish in five tributaries: the Sand, Flag, Iron, Amnicon,
and Brule Rivers. Ruffe have also been detected at Thunder
Bay, Ontario, and Alpena, Michigan (Lake Huron).(6)
Photo courtesy of University of Wisconsin
Sea Grant, Photographer: D. Jude
Gobies are capable of rapid population growth
after they reach new areas. They have shown the ability to
out-compete native fish for food and habitat because of their
aggressiveness, ability to survive in poor water quality conditions,
ability to feed in complete darkness, and long spawning period
(April through September). Another area of concern involves
potential predation on the eggs and fry of lake trout.
After first being discovered in 1990 along
the St. Claire River (a Canadian river north of Detroit),
gobies have been found in eastern and southern Lake Erie,
southern Lake Huron, southern Lake Michigan, and western Lake
Superior. They now have access to America’s largest
watershed because the Grand Calumet River (which begins at
Lake Michigan near Chicago) connects with the Mississippi
Photos courtesy of the Virginia Institute
of Marine Science
Sea lampreys prey on commercially important
fish species; such as lake trout, living off of the blood
and body fluids of adult fish. During its life as a parasite,
each sea lamprey can kill 40 or more pounds of fish. These
organisms were a major cause of the collapse of lake trout,
whitefish, and chub populations in the Great Lakes during
the 1940s and 1950s.(8)
The sea lamprey was first discovered in Lake
Ontario in 1835, Lake Erie in 1921, Lake Huron in 1932, Lake
Michigan in 1936, and Lake Superior in 1946. Reproducing populations
were found in all of these upper lakes by 1947. The present
“hot zone” is the St. Marys River. Sea lampreys
produced in the St. Marys River migrate into Lake Huron and
northern Lake Michigan. There, the adult sea lamprey population
is nearly as large as it was 40 years ago – before sea
lamprey control – when lake trout and whitefish stocks
Photo courtesy of the Center for Great
Lakes and Aquatic Sciences
Zebra mussels, Dreissena
polymorpha, are small, fingernail-sized, freshwater
mollusks accidentally introduced to North America via ballast
water from a transoceanic vessel. Since their introduction
in the mid-1980s, they have spread rapidly to all of the Great
Lakes and an increasing number of inland waterways in the
United States and Canada. Zebra mussels colonize on surfaces,
such as docks, boat hulls, commercial fishing nets, water
intake pipes and valves, native mollusks, and other zebra
mussels. Their only known predators, some diving ducks, freshwater
drum, carp, and sturgeon, are not numerous enough to have
a significant effect on them. Zebra mussels have greatly impacted
the Great Lakes ecosystem and economy.(10)
Photo courtesy of the Minnesota Department
of Natural Resources, Photographer: J. Lindgren
The spiny water flea, Bythotrephes
(bith-o-TREH-feez) cederstroemi, a small predacious
crustacean, has an average length slightly larger than 1 centimeter
(0.4 inches) of which 70% is a long, sharp, barbed tail spine.
Their rapid reproduction, general lack of predators, and direct
competition with young fish for food gives them the potential
to alter the food webs of the Great Lakes.
Spiny water fleas were first introduced
into the Great Lakes ecosystem in 1984 via ballast water that
was discharged into Lake Huron. By 1987, they had spread to
all of the Great Lakes, and currently they infect inland lakes
in Michigan and Southern Ontario.(11)
Photo courtesy of the National Oceanic
and Atmospheric Administration, Great Lakes Environmental
The oppssum shrimp, Mysis
relicta, is an opportunistic feeder with both predatorial
and filter feeding habits. Zooplankton, when abundant, serve
as the opposum shrimp’s primary food source; when scarce,
Mysis relicta will feed on suspended
organic detritus or from the surface of benthic organic deposits.
Within its native range, the opossum shrimp has been shown
to be an important prey item for freshwater fishes. However,
when introduced into what was considered to be an “empty”
niche, its impact on the aquatic community was significant.
Dramatic changes and species extinctions of native zooplankton
communities have been attributed to its opportunistic lifestyle.
Declines in the number and size of game fish have been documented
since the introduction of opposum shrimp, provoking doubt
regarding their utility as a forage base for game fishes.(12)
Photo courtesy of the U.S. Fish &
Wildlife Service, Photographer: Dr. Thomas L. Wellborn, Jr.
is a metazoan parasite that penetrates the head and spinal
cartilage of fingerling trout where it multiplies very rapidly,
putting pressure on the organ of equilibrium. This causes
the fish to swim erratically (whirl), and have difficulty
feeding and avoiding predators. In severe infections, the
disease can cause high rates of mortality in young-of-the-year
fish. Those that survive until the cartilage hardens to bone
can live a normal life span, but are marred by skeletal deformities.(13)
Whirling disease originated in Eurasia and
is now found in 22 states in the U.S. including: Alabama,
California, Colorado, Connecticut, Idaho, Maryland, Massachusetts,
Michigan, Montana, Nevada, New Hampshire, New Jersey, New
Mexico, New York, Ohio, Oregon, Pennsylvania, Utah, Virginia,
Washington, West Virginia, and Wyoming. Internationally, South
Africa and New Zealand have been invaded by the parasite.(14)
Photos courtesy of the South Carolina
Department of Natural Resources
MSX (Multinucleated Sphere X) disease is caused
by a single-celled Protozoan parasite, Haplosporidium
nelsoni. MSX is lethal to the eastern oyster, but it
is not known to be harmful to humans.(15)
Recently, according to the Washington Post, scientists have
found genetic evidence that implicates Japanese oysters as
the cause of MSX.(16) Its life
cycle and means of infecting oysters still remain as mysterious
now as they did forty years ago. Its first appearance in mid-Atlantic
waters was in Delaware Bay in 1956 where it ravaged oyster
beds; the next year it arrived in the Chesapeake Bay.
VHS (viral haemorrhagic
septicaemia) is the most serious viral disease of salmon
and trout in Europe. It kills up to 90% of the juveniles in
fish farms and hatcheries, and up to 40% of infected adults.
Historically, VHS has been a disease
of European rainbow trout and primarily a problem in freshwater.
It has been known in rainbow trout in Europe since 1938. The
disease is seen in most countries of continental Eastern and
Western Europe. Until 1988, it had not been present in the
United States. However, the VHS virus has now been found in
saltwater, and in the U.S. VHS virus was first isolated here
in the U.S. in adult coho salmon returning to a hatchery in
the Puget Sound area of Washington state.(18)
Photo courtesy of the U.S. Environmental
Protection Agency, Photographer: Karen Holland
Purple loosestrife (Lythrum
salicaria) grows so densely that it crowds out, kills,
and replaces native plants. This is particularly devastating
because purple loosestrife replaces plants that animals depend
on for food and shelter; and, it has no food and little shelter
value. Muskrats are dying out in some areas because their
diet of cattails has been severely reduced by purple loosestrife.
Infestations can become so bad, that they block water flow.
Purple loosestrife can reduce biodiversity rates from 900
to 1 species.(19) This invasive
plant can produce up to 2.7 million seeds per plant yearly,
and spreads across approximately 1 million additional acres
of wetlands each year.(20)
Purple loosestrife is a perennial plant native
to Europe. It was brought to North America in the early 1800s
by immigrants who valued its striking purple flowers. Seeds
were also unintentionally transported to the shores of North
America in the ballast water of ships. Since then, purple
loosestrife has expanded its range; now, it is a serious pest
of wetlands and pastures.(21)
(1) Providence College. Political Science Dept. “Ballast
Water & Exotic Species.” 3 June 2003 <http://www.providence.edu/polisci/projects/megaport/ballast.htm>.
(2) Raines, Ben. “Invasive
Species, Disease Share Berths in Ship Ballast.” Newhouse
News Service, 2 February 2002. 3 June 2003 <http://www.newhousenews.com/archive/story1c020201.html>.
(3) Smithsonian Environmental Research Center. Marine Invasions Research
Ballast Water Management Strategies.” 3 June 2003 <http://invasions.si.edu/NBIC/nbic_mgmt.htm>.
(4) Tibbetts, John. “Exotic
Invasion.” Environmental Health Perspectives 105 (Number
6) (June 1997). ehp Online. 3 June 2003 <http://ehpnet1.niehs.nih.gov/docs/1997/105-6/spheres.html>.
(5) Vermont Agency of Natural Resources. Dept. of Environmental Conservation.
3 June 2003 <http://www.anr.state.vt.us/dec/waterq/ans/alewife.htm>.
(6) U.S. Geological Survey. Upper Midwest Environmental Sciences Center.
Ruffe.” 3 June 2003 <http://www.umesc.usgs.gov/invasive_species/eurasian_ruffe.html>.
(7) U.S. Geological Survey. Upper Midwest Environmental Sciences Center.
Goby.” 3 June 2003 <http://www.umesc.usgs.gov/invasive_species/round_goby.html>.
(8) U.S. Geological Survey. Upper Midwest Environmental Sciences Center.
Lamprey.” 3 June 2003 <http://www.umesc.usgs.gov/invasive_species/sea_lamprey.html>.
(9) National Sea Grant Nonindigenous Species Site. “Sea
Lamprey(Petromyzon marinus).” 3 June 2003 <http://www.sgnis.org/www/lamprey.htm>.
(10) National Sea Grant Nonindigenous Species Site. “Zebra
Mussel (Dreissena polymorpha).” 3 June 2003 <http://www.sgnis.org/www/zebra.htm>.
(11) Berg, David J. “The
spiny water flea, Bythotrephes cederstroemi: Another unwelcome newcomer
to the Great Lakes.” Ohio Sea Grant. Revised 1992. Sea Grant
Nonindigenous Species Site (SGNIS) 3 June 2003 <http://sgnis.org/publicat/papers/bergdj92.pdf>.
(12) Foster, A.M. “Mysis
relicta Lovén.” U.S. Geological Survey. Center for
Aquatic Resource Studies. 6 October 1999. Nonindigenous Aquatic Species.
3 June 2003 <http://nas.er.usgs.gov/crustaceans/docs/my_relic.html>.
(13) Whirling Disease Foundation. “The
Challenge of Whirling Disease.” 3 June 2003 <http://www.whirling-disease.org/disease.html>.
(14) Markiw, Maria E. “Salmonid
Whirling Disease.” National Fisheries Research Center-Leetown
National Fish Health Research Laboratory, U.S. Fish and Wildlife Service.
1992. U.S. Geological Survey, Leetown Science Center. 3 June 2003
(15) State of Connecticut. Dept. of Agriculture. “Oyster
Diseases.” 3 June 2003 <http://www.state.ct.us/doag/business/aquac/oysdisea.htm#MSX>.
(16) Huslin, Anita. “Cholera
Found in Water From Freighters.” Washington Post, 2 November
2000. mindfully.org. 3 June 2003 <http://www.mindfully.org/Water/Cholera-Water-Freighters-Chesapeake.htm>.
Oysters to U.S. Coastal Waters: Oyster Foes East & West.”
Maryland Sea Grant. 3 June 2003 <http://www.mdsg.umd.edu/oysters/disease/foes/>.
(18) Brown, Laura L. and David W. Bruno. “Infectious
Diseases of Coldwater Fish in Fresh Water.” National Research
Council of Canada, Institue for Marine Biosciences and Fisheries Research
Services, The Marine Laboratory. 2002. CABI Publishing. 3 June 2003
(19) Community Consolidated School District 89, Glen Ellyn, IL. “Purple
Loosestrife.” 3 June 2003 <http://www.ccsd89.org/teachers/bg/sherrmann/purpleloosestrife.htm>.
(20) National Agricultural Library for the National Invasive Species
are the Impacts of Invasive Species?” 3 June 2003 <http://www.invasivespecies.gov/impacts.shtml>.
(21) Vermont Agency of Natural Resources. Dept. of Environmental Conservation.
loosestrife.” 3 June 2003 <http://www.anr.state.vt.us/dec/waterq/ans/plpage.htm>.
|This package was last updated on July 1, 2003.