Every hour an average of more than 2 million gallons of ballast water, meaning 2 million gallons of foreign plankton, are released in U.S. waters . Ballast water may be the source of the largest volume of foreign organisms released on a daily basis into American ecosystems. Source: James T. Carlton, Endangered Species Update Vol.12, 1995
What is Ballast water
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 new bay. Ballast stablizes 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. Over 3,000 marine species travel around the world in ships' ballast water on a daily basis.
Source: James T. Carlton, Professor of Marine Sciences at Williams College, Understanding Marine Biodiversity,1995
What are invasive species?
The species carried in ballast water are called exotic species, alien species, invasive species, or nonindiginous species, all meaning a member, or members of a group or population, of a species that enters an aquatic ecosystem outside of its historic or native range.
Invasions of exotic marine animals and plants into American coastal waters are not new. Wooden ships transported innumerable species both in them (as boring organisms) and on them (as fouling communities). In the last quarter of the 19th century, commercial oysters began to be moved around the world in huge numbers. With them came an untold number of epizoic and endozoic species, as well as entire estuarine communities in the mud and seaweed packed with these oysters. The world's oceans began to be biologically homogenized centuries ago. Yet, despite the successful movement of hundreds of species over these decades, the speed of modern ships and the volume of ballast water now carried are two of several factors that may be in the process of successfully overwhelming these earlier centuries of transport in terms of the number of successful invasions. Invasive species have recently been discovered because of their detrimental economic impact in the Great Lakes causing billions of dollars of damage. Other means of exotic species introduction include the aquarium trade, military, recreational marine vessels, research institutions, seafood commodity distribution
The problem:
Invasive species feed on native species thus eliminating a vital part of the native food chain. Economic and environmental damage occur when nonindiginous species are introduced.
Effects on biodiversity:
Biodiversity can change in three ways: species can be added (invasions, natural or human-mediated), deleted (extinctions, also natural or human-mediated), or relative abundances can change (of native species and of previously introduced species). Taken strictly on a species head-count basis (that is, species "richnes"), as noted above, there appear to be more species in a given region after invasions. The evidence for endangerment or extinctions of native marine species at the hands of marine invasions is almost non-existent. This is not to say that it may not have occurred or may not be occurring; a related problem in marine science is that almost nothing is known of extinctions in the ocean below the level of mammals and birds (Carlton, 1993).
On the other hand, there is mounting experimental and empirical evidence that invasions have striking impacts on the proportions of native species. The invader may become, for example, the space-dominant species, or an abundant predator. But for most marine invasions we have only time to record them and move on, in part because there are so many invasions now occurring. The same is true in almost all ecosystems, meaning that most invaders enter a community from which there are no subsequent reports of ecological "cascading" of any kind. This has led more than a few workers to conclude that such invaders have had no impact on the invaded systems, a conclusion that should be drawn, of course, only after species-specific studies, preferably experimental, are conducted.
As these harbor-based biotas begin to build up around the world, a global cosmopolitan marine biotic facies begins to appear, not unlike the earlier development of cosmopolitan terrestrial weed communities. While we seek to preserve aboriginal species diversity, and while we continue to attempt to determine if marine invasions in the ocean are threatening any native invertebrates, vertebrates, or plants, we also seek to preserve community (habitat) and ecosystem diversity. It is here, in the preservation and conservation of supra-specific diversity levels, that one of the greatest ecological challenges of marine invasions lies (there being, of course, for some invaders, critical economic, social, industrial, and human-health challenges as well). Ballast water transport is non-selective relative to the habitat diversity or the trophic categories of transported organisms (Carlton and Geller, 1993). With more than 3000 species a day being transported in ships around the world (NRC, 1995), it would appear to be simply a matter of time before a sufficiently broad array of invasions occurs such that almost every estuarine, near-shore habitat would support some percentage of invasions, thus rendering the concept of preserving aboriginal community diversity mute.
Ballast water invasions continue, and they will continue for some years to come. National and international regulations (largely now voluntary) that call for ballast water management interface with a huge maritime industry that directly involves more than 130 nations, with a staggering variety of vessels of different sizes, cargoes, age, condition, routes, and ballasting requirements. Vessels are being built in 1995 with an expected at-sea life of 25 or more years, without regard to ballast management considerations.
In the U.S., ballast water management guidelines are now in effect, as federal law, in the Great Lakes and in the Hudson River. In these two regions arriving ships must have their ballast water no lower than 30 parts per thousand salinity, and must have exchanged their water if possible on the high seas in depths exceeding 2000 meters. However, problems with open ocean ballast exchange, ranging from limited effectiveness to concerns about crew and ship safety, have arisen. These are leading committees and research groups around the world to look toward more long-term solutions, specifically focused on treatment of the ballast water aboard ship. The U.S. National Research Council's Marine Board has thus formed the "Committee on Ships' Ballast Operations," to meet from 1994-1996, to sort through the more than 50 proposed solutions and recommend pathways to consider.
National InvasiveSpecies Act
Effects on industry:
Introduction of exotic species have been known to damage the stock of commercial fisheries. The following examples of invasion species have been introduced by ballast water.
Six countries near the Black Sea have been affected by the Atlantic comb jelly. It has eliminated the zooplankton in the Black Sea which has exhausted the region's anchovy fishery.
Shellfish in Tasmania have been wiped out by North Pacific sea stars.
Toxic red tides have closed clam and mussel farms and fisheries. Both of these invasive species were introduced by ballast water.
It has been estimated that $44 million in annual fisheries revenues in Oregon and Washington state are vulnerable to the purple varnish clam aand the green crab. (Science News, June 13, 1998, p. 373).
The European zebra mussel was introduced into the Great Lakes in the 1980's and caused billions of dollars of damage. The zebra mussel clogged the water systems for cities, and factories and power plants. Fouling boat hulls and maritime structures and sinking navigational buoys, and accumulating on recreational beaches, fouling them with sharp-edged mussel shells and rotting mussel flesh.
Effects on human health:
A recent red tide outbreak in New Zealand was so severe that people breathing the sea air became ill. Ballast water can also transport cholera around the world. In 1991 the South American cholera epidemic was a result of the cacterium discovered in oysters and fish in Mobile Bay, Alabama. 1/3 of the ships arriving from South America in Alabama carried this bacterium.