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Ballast Water Pollution:
The Introduction of
Non-indigenous Species
Sarah Grubs
December 19, 2003
©Do not copy any of this material without permission from the author.
Used on this web site with author’s permission.
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Increasingly we are seeing species of freshwater, estuarine and marine organisms sprawl
out from their native regions through human mediated transport. Many of these
organisms have profoundly affected the abundance and diversity of native biota in their
receiving environments, often causing significant environmental and economic impacts
(Cohen 1998). These species have been introduced through several mechanisms, the
most common are through the movement of fouling communities on the bottom of ships,
through the intentional release of aquaculture, fisher and bait species which includes a
host of associated free living and parasitic organisms, through the connection of
waterways via canals and through the release of organisms in ballast related materials of
ships (Ruiz1997). The last of these poses the greatest environmental and economic threat
with over 10 billion tons of organism infected ballast water being introduced into ports
around the world each year (Reeds 1999, Zhang 1999). Shockingly, over 400 nuisance
non-indigenous species (NIS) are known to be established in marine and estuarine
habitats in the U.S. alone (Ruiz, Fofonoff & Hines 1999), 76 of the NIS have made
repeated invasions in other ports along the coast due to intracoastal shipping (Ruiz 2000).
The rate of introduction is showing no signs of leveling off; in fact NIS introduction
continues to climb exponentially due to changes in shipping practices, increased
eutrophication of estuarine environments and the lack of enforced regulations on the
exchange of ballast water (Cohen 1998, Harvell1999, Ruiz 2000).
History
Ballast is an absolute necessity to the shipping industry; it is stored in dedicated
ballast tanks that line the hull of the ship (figure 1).
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Figure 1 Diagram of ballast tanks lining the hull of a cargo ship (Hallegraph & Bolch 1991)
The ballast performs several functions when cargo is absent, it controls the
stability and trim of the vessel allowing the ship to steer through coastal waters and
preventing it from capsizing in rough open ocean waters. It also serves to balance the
stresses the ship’s hull experiences as well as increasing efficient fuel consumption
(Kelly 1993, Zhang 1999).
The original forms of ballast were mainly dry, sailors would use rock, gravel and
seaweed they obtained at the port they happened to reside in, to balance their ships
(Reeds 1999). In fact, prior to 1870 the introduction of non-indigenous species occurred
mainly through hull fouling of the wooden ships (Ruiz 1997). Today very few organisms
are carried into foreign ports on the hulls of ships due to the increased speed, anti-fouling
paints and low port residency times. Ballast took a revolutionary turn at the end 19th
century with the creation of steel ships. This evolution allowed for the use of water as
ballast which took less time and man power to fill the tanks, it also created a new more
efficient method of NIS introduction (Kelly 1993).
Ballast Today
Today the movement of ballast water between ports is claimed to be the largest
single vector in the introduction of NIS (Aliotta 2001; Carlton 1985; Dickman 1999;
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Lavoie 1999; Kelly 1993; Ruiz 2000; Zhang 1999). The increased rate of introduction is
attributed to the increase in size and number of cargo ships, the increase in their speed
and the increase in the eutrophication of estuaries (Zhang 1999). Ballast is most
frequently taken on while ships are in port, these ports lie in bays and estuaries that are
laden with potentially pathogenic diatoms, dinoflagellates, bacteria such as Vibrio
cholerae, viruses and the larvae of various crustaceans, bivalves and vertebrates. This
water is then transported inter and intra coastally where it is then discharged upon arrival
in a foreign port (Carlton 1996). The success of a ballast-mediated invasion depends on
several factors, an organism must first survive the voyage; for species such as
Clostridium, dinoflagellates and diatoms this is an easy task due to their ability to form
spores and cysts (Kelly 1993). Upon their release from the ballast tank they may
encounter problems such as pump effect in which they are damaged via the pump in the
discharge of the water. If they are discharge unharmed they must then adapt and
establish in their new environment in numbers significant enough to reproduce (Lavoie
1999). This task is not impossible when you consider that San Francisco Bay alone has
experienced the establishment of 234 known NIS (Carlton 1990). The nature of the
cargo shipping industry creates a habitat that gets regular inoculations of water from
specific regions on a frequent basis (Lavoie 1999).
Bulk cargo ships are normally
contracted to carry cargo for only one leg of each voyage which requires them to travel
“in ballast” the other half of the time. Countries that have a large amount of export
therefore stand to be the recipient of the majority of foreign ballast water as is the case
with the United States and Australia (Kelly 1993).
Australia receives 60 million tons of
ballast water every year, most of which is from Japan (Hallegraeff & Bolch 1992) while
the United States receives over 79 million tons of ballast water yearly from around the
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world (Ruiz 1997). The frequency and intensity of ballast water discharge in these
countries and around the world has resulted the introduction of hundreds of organisms
that have had huge economic impacts. The U.S. alone has an estimated economic impact
of $100 billion. (Ruiz 2001).
The Extent of the Problem
Zebra Mussel, Dreissena polymorpha
The Zebra mussel was first discovered in the Great Lakes in the 80’s. It was
introduced from the Black and Caspian Sea where it lives in normal numbers and in
balance with its environment (Carlton 1996). Since its introduction it has successfully
spread through connected water ways from the Great Lakes to Arkansas (Figure 2)
(Reeds 1999).
Figure 2 Map of the spread of the Zebra Mussel throughout the
United States. Red indicates highest concentrations
of mussels (http://globallast.imo.org)
A female zebra mussel is able to lay 1 million eggs in one summer. Once hatched
the larvae are microscopic and are able to travel long distances. Today populations of
zebra mussels have reached a staggering 70,000 individuals per meter squared (Reeds
1999). The mussels have had huge ecological and economic impacts in the U.S. They
occur in such significant numbers that they clog intake pipes to many facilities and coat
the hulls of any ship in their vicinity. More importantly they have wreaked havoc on the
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environment through the disruption of the base of the food chain. These mussels have
effectively filtered 80% of the phytoplankton biomass in the habitats they infest. This
has led to greater light penetration altering the composition and density of the vegetation
in lakes all along the Mississippi (http://www.anr.state.vt.us/dec/waterq/ans/zebra.htm).
Gymnodinium catenatum
Hallegraeff and Bolch have done extensive research on species introduced to
Australia. Australian economy relies heavily on the export of raw materials such as coal,
grain, iron ore and wheat. The ships export these commodities in one direction, returning
with their ballast tanks full of water from foreign ports. (Hallegraeff & Bolch 1991). In
the study of 343 ships entering 18 Australian ports they discovered that 65% of the ships
carried sediment with non-indigenous diatoms and 50% of the ships contained the resting
spores of non-indigenous dinoflagellates, one particular ship had apparently ballasted
during a dinoflagellate bloom and contained over 300 million species of a dinoflagellate
known to cause paralytic shellfish poisoning (Hallegraeff & Bolch 1992).
The regular
inoculation of these species has created dinoflagellate cyst beds in and around Australia.
In 1986 and again in 1991 toxic blooms of these species caused the closure of 15 shellfish
farms for periods of up to 6 months. These benthic cyst beds are now widespread
throughout Australia and Tasmania making what has been a family business for century’s
economic time bombs (Hallegraeff & Bolch 1992).
Infectious Salmon Anemia
Infectious salmon anemia virus (ISAV) is an emerging disease that has caused
severe damage to the salmon-farming industry. This virus causes lesions on the gills of
salmon that inhibits the fishes’ respiration (Figure 3).
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Figure 3 A lesion produced on the gill of salmon
infected by infectious salmon anemia
(http://www.umaine.edu/livestock/Publications/isa.htm)
ISAV was discovered in Norway in 1984, it is a virulent strain of virus that has
adapted to the intensive aquacultural practices. In 1998 it was introduced to Scotland in
the ballast water of well boats. The well boats had foolishly ballasted next to the
processing plants effluent which was contaminated with the blood of infected salmon.
ISAV has since spread to Canada, the Faroe Islands and in 2000 it was sadly reported in
Maine. Although the economic impact in the United States is not yet estimated, ISAV
has already caused over $60 million in damage a year in other countries (Murray, Smith
& Stagg 2002).
Current National and International Policy
The United States has done relatively little in the protection of our estuaries in
regard to NIS introduction. The mid-ocean exchange of ballast water is currently the
only suggested management strategy in the prevention of NIS. This consists of ships
exchanging the eutrophic port water for open ocean water when they are in waters greater
than 2000m deep and outside the Economic Exclusive Zone (EEZ), a 200 mile strip of
ocean surrounding all United States territory (Aliotta 2001). In contrast to coastal waters,
mid-ocean waters are poor in nutrients and contain relatively few organisms. The
organisms present in open-ocean waters are oligotrophic in nature and in theory have a
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low likelihood of being able to survive in the nutrient rich waters of ports (Zhang 1999).
Until 1990, the U.S. did not have any written restrictions on ballast water. The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 was the first attempt at
regulating ballast exchange. This act required that all ships entering the Great Lakes
undergo ballast water exchange prior to crossing the EEZ.
(http://invasions.si.edu/NBIC/nbic_mgmt.htm). The National Invasive Species Act
(NISA) of 1996 reauthorized and amended the Nonindigenous Aquatic Nuisance
Prevention and Control Act of 1990 to include a required a mandatory ballast water
report be filed with all ports in the U.S. declaring the intent and treatment of any ballast
water on board. It also requested the voluntary compliance of mid-ocean exchange prior
to entering U.S. waters (Dickman 1999). These acts are voluntary and provide little in
the way of incentive to the shipping industry. Even if the acts requested mandatory
exchange, enforcement and monitoring (which requires a simple salinity test) would not
be feasible due to the lack of money and the shear number of ships that entering U.S.
ports daily. This is fact is unfortunately evident when one observes to what extent
compliance has been less than desirable; figure 4 shows the points of exchange within the
United States from 1999 to 2001. The majority of ballast water exchange has occurred
within the EEZ (Ruiz 2001).
Figure 4 Reported ballast water exchange locations for individual ballast tanks
on vessels arriving to the United States between July 1999 and
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June 2001. Gray shading indicated EEZ (Ruiz 2001).
In a study conducted by Ruiz of the 28,988 foreign arrivals that submitted reports
(which consequently was only 30% of all ships arriving) 73.6% indicated no intention to
discharge ballast water in the U.S., 12.9% declared no open ocean exchange of ballast
water prior to discharge in port and 13% declared only some degree of open-ocean
exchange prior to discharge in port. Of the 73.6% of vessels claiming no intent to
discharge in U.S. almost all of them had ballast water on board (Ruiz 2001). Conducted
interviews of ships officers confirmed that while some ships practice ballasting and deballasting procedures, all ships routinely discharge some volume of ballast water and
sediments into local waters (Kelly 1993). It is apparent that the acts passed to regulate
NIS introduction have been met with less than little enthusiasm by the shipping industry.
The lack of enthusiasm is most likely due to the problems that mid-ocean exchange pose.
Exchange of ballast water is simply not feasible for ships in rough water due to the
increased vulnerability of ships without ballast. In addition to the integrity of ships,
exchange is more frequently not performed due to itinerary and shipping schedules. The
shipping industry is of course; entirely driven by financial gain and failure to arrive to
port on time can result in the loss of a contract for an entire shipping fleet (Ruiz 2001).
All of the shipping industry oppositions aside, the most alarming problem with
open-ocean ballast water exchange is not compliance but the actual effectiveness of the
management itself. The effectiveness of ballast water exchange as a national
management strategy is seriously disputed. Theoretically for a ballast tank in which all
organisms are homogenously distributed throughout the water column, the current
method for exchange would be 95-99% effective as claimed by the National
Clearinghouse for Ballast Water. Many of the leading scientists in ballast water
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management have conducted studies in the effectiveness of open-ocean ballast water
exchange in which their findings have given a much more dismal percentage of
effectiveness for open ocean ballast exchange. In 1999 Zhang and Dickman conducted
tests on the effectiveness of exchange based on vessel type. They discovered that many
of the older vessels were not efficient in removing the water and sediment located near
the bottom of ships. The ships coming out of Manzanillo, Mexico had an open-ocean
exchange of only 48% effectiveness, upon closer examination it was discovered that
many of the diatoms and dinoflagellates in the ballast tank after exchange were coastal
species which leads to the conclusion that a percentage of the coastal water was not
exchanged (Dickman & Zhang 1999). Ballast tank gauges confirmed the suspicion
indicating that during exchange there is typically a small amount of water 1-5% that is
retained in the bottom of the tank. This water is of particular concern because in contains
sediment that has settled to the bottom, this sediment in turn contains cysts, spores and
dormant cells of organisms which leads to the 1-5% of water left having an unusually
high density of organisms (Zhang & Dickman 1999). As a marine biologist with a
microbiology background I can comfortably say that given the asexual nature of many of
these organisms this would be more than sufficient to induce rapid proliferation upon
introduction to a compatible habitat.
Hallegraeff and Bolch confirmed these findings in their 1992 study in which 14 of
the 32 vessels they examined contained significant numbers of dinoflagellate cysts even
after mid-ocean exchange (Hallegraeff & Bolch 1992).
The sediment contained in ballast tanks is not currently under any type of
mandate or regulation in the United States and yet it poses every bit as much a
considerable threat as its associated ballast water. Current management for the shipping
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industry simply involves the routine maintenance of the tanks in which the sediment is
collected to be disposed of later. Kelly performed research into the fate of these
sediments in the state of Washington. She discovered that of all the ships that were
sampled the sediment taken from the hold ranged from 600-1900 liters. When
questioned, 4 of 6 officers stated that sediments would remain stored on deck until the
ship was outside harbor waters before they would be dumped. Her personal observations
were that “a significant amount of these sediments were discharged into port waters
during de-ballasting of water, cleaning of the hold and subsequent clean of the ship
decks” (Kelly 1993). With the continuing increase in the rate of introduction of NIS it is
obvious that existing management is not sufficient, we must then look to other forms of
management.
The Future of Ballast Water Management
Several other forms of ballast water purification are currently being researched by
scientists around the world. Some of the most promising include; heat treatment,
Ozone treatment, and a method that I have personally been researching ElectroIonization. For a ballast water treatment technology to be approved by the National
Ballast Water Clearinghouse it must prove to be more effective than open-ocean
exchange (http://invasions.si.edu/NBIC/nbic_mgmt.htm). Other criterion the
treatment system must fulfill is to be safe to the ship and crew, environmentally
friendly, compatible with ship design and operations and cost effective (Aliotta
2001). The U.S. Fisheries and Wildlife Services and National Oceanic and
Atmospheric Administration (NOAA’s) National Sea Grant College Program have
taken the first step in promoting the development of these new technologies through
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the funding of efforts to advance the research and technology of secondary forms of
ballast water treatment (Cangelosi 1999).
Ozone treatment involves the production of a biocide through the injection of
ozonated gases into the ballast tank. Ruiz has been the leading scientist in the exploration
of the possibility of ozone as a secondary treatment for ballast water. Studies conducted
by Ruiz have documented the production of bromoforms in the range of 50ppm, which
would be extremely toxic to an environment if immediately released. The coinciding
production of elemental oxygen holds some promise of aiding the volatilization of
bromine after production but needs further research (Cooper 2002).
Ozone however requires an extremely long exposure time with a 99% kill rate
only after ten hours of exposure. Ruiz has also explored the possibility inconsistent
results due to lower temperatures that may account for lower bromoform formation
(Cooper 2002).
Heat treatment involves the use of ballast water in cooling engines, the engines
heat will counter act as an environmentally safe biocide to kill organisms within the
water. Preliminary sea trials undertaken by Mountfort between Wellington and Auckland
in 2000 involved the heating of ballast water from 24-42 degrees Celsius over a 10 hour
period. The results unfortunately were only 60% effective in killing the starfish larvae
that the tank was seeded with (Mountfort & et al 2000). Heat treatment would not be a
possible form of secondary management in waters that have temperatures below 15
degrees Celsius due to time constraints in the heating of the water.
Electro- Ionization consists of primary removal of larger debris with a 50 micron
filter followed by a cell that produces bromine from seawater through electrolysis. The
bromine is then in theory driven off by hydrogen peroxide produced through ionized air
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that is injected into the system after the electrolysis. This should then render the effluent
deficient in bromine biocide and absent of viable organisms (Aliotta 2001). As I stated
earlier I have been performing tests on this system for close to a year now. Unfortunately
I have serious doubts in the effectiveness of this system for several reasons. I do not
support the idea of filtration prior to treatment. Removing all of the primary consumers
from ballast water, as a 50 micron filter will do, would cause drastic tank effects in which
bacteria, viruses, diatoms and dinoflagellates would be able to proliferate in the absence
of predators. This could create an environment that was abundant in the organisms that
are the most resistant to biocide, dinoflagellate cysts. I believe that the effectiveness of
the system would be increased if the ciliates and copepods were not filtered out of the
water so that they would be able to keep the dinoflagellates and diatoms in treatable
numbers. I have yet to be able to test this theory. In addition to the filtration I have not
seen a reduction in bromine after the introduction of the ionized air which leads me to
believe that the company I have been testing for has little more than a pool chlorinator.
Electro-ionization needs further tests to explore the effectiveness in freshwater habitats as
well.
Despite the individual shortcomings of these systems with further development
and research they could hold promise for a secondary treatment to ballast water. An
important step in furthering the development is the establishment of standards. As we
have seen the current strategy for management has produced effectiveness as low as 48%.
A good portion of the discrepancy is from the various methods used to test for organisms
and the individual organisms that are used. Without standard methods and specific
indicator organisms treatment and management cannot be compared objectively and the
debate about solutions to ballast water will remain unfocused. One month ago a
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laboratory in the Keys was given the task to test surrogates and develop standards funded
by the National Sea Grant College Program. This is an important step towards the
unifying of a national set of standards upon which we can compare treatments.
Until the time we develop a set of standards we must do everything we can to
increase the effectiveness of open-ocean exchange. Laws must be implemented making
it a necessity to perform exchange outside the EEZ. Enforcement of these laws will be
expensive but possible sources of funding could be from fines that would be assessed
from ships that did not undergo exchange. With the increasing number of ships that enter
ports every day a small percentage of port taxes would generate substantial amounts of
money.
As new ships are constructed design should be focused on more efficient ballast
tanks that allow the removal of all water and decrease the amount of sediment that builds
up in the bottom of the tanks. A design that holds promise is an inverted funnel that
drains ballast water through the bottom. Ruiz is currently testing the effectiveness of this
design and has yet to make the results available to the public (Cooper 2002).
Globallast has several economically feasible suggestions for the shipping industry
until such time a technology is presented that makes open-ocean ballast exchange a
thing of the past. They suggest that ballasting is avoided in waters that are
experiencing toxic dinoflagellate blooms which are indicated by a discoloring of the
water. Secondly a 300% water exchange out of the EEZ would reduce the amount of
residual coastal organisms retained. Finally ballasting should never occur at night
because this is the time that plankton raises in the water column increasing organism
density at the surface where ballast water is taken (http://globallast.imo.org).
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The task of curbing the introduction of non-indigenous species is certainly not an
easy one but it is feasible if we start focusing our efforts and increasing the resources
we invest into the management and development of technologies. Ballast water
management will provide invaluable benefits to not only the United State but the rest
of the world that will decrease economic and environmental loss while assuring
biodiversity for generations to come.
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http://www.umaine.edu/livestock/Publications/isa.htm
http://www.anr.state.vt.us/dec/waterq/ans/zebra.htm