How are invasive marine species transported and what effect does that have on our ocean
ecosystems? [Kennedy Hall]
"The National Research Council has ranked invasive species and over exploitation as the
most serious threats to native biodiversity" (Rosamond, Williams, and Strong 1655). Marine bioinvasions are caused because of human involvement and interference within our oceans. Marine
organisms do not transport themselves to a new location across the ocean. They are transported
via ships, often involved in trade, and often escape into native waters through the practice of
aquaculture. Invasive marine species cause ecological as well as economic stress. One of the
largest ways in which marine species are transported is through the ballast water in ships. Ballast
water is collected in the harbor to balance the ship before it goes out to sea. Once the ship arrives
at its destination, the ballast water is emptied so the ship can dock. Nicholas Bax, researcher at
the Centre for Research on Introduced Marine Pests, stated in his article, "Marine invasive alien
species: a threat to global diversity," from the peer-reviewed journal Marine Policy, "At any
given moment some 10,000 different species are being transported between bio-geographic
regions in ballast tanks alone" (Bax 313). Ballast water not only contains foreign organisms, it
can also contain viral and bacterial pathogens that result in illness for either humans or native
aquatic species (Bax 314). According to Jeffrey A. Crooks, research coordinator for the Tijuana
River National Estuarine Research Reserve, with a Ph.D. from Scripps Institution of
Oceanography, and Gil Rilov, senior researcher at Israel Oceanographic and Limnological
Research Institution, the growth of trade has lead to an increase in the dispersal of marine
organisms, by attaching to the hulls of ships and stowing away in the ballast water (3).
Unfortunately, "the invasion of non-native species has increased exponentially in the past 200
years, and does not show signs of slowing down or leveling off (Rilov and Crooks 4). Ballast
water is only one of the ways in which invasive marine species are released into our native water.
Another way in which they are release is through the practice of aquaculture, or fish farming.
In "Aquaculture- A Gateway for Exotic Species," in the online journal, Science, authors
Taylor L. Rosamond, director of Center on Food Security and the Environment, Susan L.
Williams, holder of the Distinguished Service Award from the Coastal and Estuarine Research
Federation, and Donald R. Strong, professor of Evolution and Ecology at the University of
California, discuss fish farming in the food industry and how it has resulted in the release of
invasive marine species. Around the world, aquaculture has contributed to the release of exotic
marine species, including but not limited to fish, parasites, and pathogens (Rosamond, Williams
and Strong 1655). As aquaculture expands, the number of invasive marine species is increasing,
due to the accidental escapes or purposeful releases of the farmed species (1655). It seems as
though people do not understand the effects these foreign species have on our environment. That
is why legislature needs to be put in place to monitor and prevent the introduction of exotic
marines species into our native waters as aquaculture expands (Rosamond, Williams, and Strong
1656). Aquaculture and ballast water are only two of many ways in which exotic species are
introduced, but the more important focus is what effects result from these introductions.
The first and most obvious effect of invasive species is a threat to biodiversity. Invasive
species can either directly prey on native organisms, or can alter the environment in which they
inhabit. For example, "Freshwater mollusks are the most endangered group of animals in North
America, and 90% of native mussel species designated as endangered, threatened, or of special
concern are found in the Southeast where the catfish industry is concentrated (Rosamond,
Williams and Strong 1655). In addition to preying on native species, Many invasive species can
be considered system engineers—that is, rather than just blend in to their new environment, they
will change it (Bax 313). Bill McAuliffe, a writer for the Star Tribune for the past 32 years,
published the article, "Zebra mussels encroaching on BWCA," in the Minneapolis newspaper,
where he discussed the effects the exotic species of zebra mussels have on the environment. It is
assumed that zebra mussels were brought to North America from Europe via ballast water and
within 25 years spread inland to lakes, streams, and even the Mississippi River (McAuliffe).
Zebra mussels do not prey on any known native species, but they harm fish populations because
they filter nutrients from the water (McAuliffe). This leaves the lake water cleaner, but that
means there is no food for the native fish species (McAuliffe). Exotic species threaten
biodiversity through direct and indirect contact, as well as causing economic stress.
A less obvious impact resulting from invasive marine species is economic damage. One
example of fiscal strain is due to human health issues resulting from exotic bacteria and
pathogens (Bax 314). Also, the food industry is suffering because invasive species are wiping out
popular menu items. The Chesapeake Bay oyster population diminished as a result of the
introduced foreign protozoan MSX (Rilov and Crooks 4). Now that we are aware of the impacts
of bio-invasions, there are economic costs associated with the management and prevention of
introductions of exotic marine species (Rilov and Crooks 4).
Human technology and involvement in our oceans is the sole cause for the spread of
exotic marine species. Exotic, and presumably invasive species, harm the biodiversity of our
native organisms and cause stress to our economic system. As we become more aware of the
causes and effects of invasive marine species, policies should be put into place to prevent more
introductions and manage the invasions we currently have, in order to protect our ecological
system.
Works Cited
Bax, Nicholas, et al. "Marine Invasive Alien Species: A Threat to Global Diversity." Marine
Policy 27 (2003): 313-323. Web. 6 Oct. 2014.
This peer-reviewed article was found using VCU Libraries (Journal Search), using the
search terms "invasive marine species." [Kennedy Hall]
McAuliffe, Bill. "Zebra Mussels Encroaching on BWCA." Star Tribune [Minneapolis] 29 May
2014, Metro ed.: B1. LexisNexis. Web. 8 Oct. 2014.
This news article was found using LexisNexis, using the search terms "invasive marine
species." [Kennedy Hall]
Rilov, Gil, and Jeffery A. Crooks. "Marine Bioinvasions: Conservation Hazards and Vehicles for
Ecological Understanding." Biological Invasions in Marine Ecosystems Ecological,
Management, and Geographic Perspectives. Eds. Gil Rilov and Jeffery A. Crooks.
Berlin: Springer, 2009. 3-9. Print.
This book was found using VCU Libraries (Book search), using the search terms
"invasive marine species." [Kennedy Hall]
Rosamond, Naylor L., Susan L. Williams, and Donald R. Strong. "Aquaculture-A Gateway for
Exotic Species." Science. 294 vols. (2001): 1655-1656. ProQuest. Web. 10 Oct. 2014.
This peer reviewed article was found using the Discipline-Specific database
Environmental Sciences under Biology. This led me to the Environmental Science
Collection (ProQuest). I first used the search terms "invasive marine species" but that was
too broad. I then used the terms "invasive marine species United States" and narrowed
the results to peer-reviewed, full text articles only. [Kennedy Hall]