Review Panel: Natalie Ferguson, Stefan Cafaro, and Brianca King
Bryan Lockwood, “The Efficiency of UV Disinfection and Crumb Rubber Filtration on the Invasive Species Content in Ballast Water”
Lockwood’s pre-proposal addresses the problem of the transfer of aquatic invasive species through ballast water. Lockwood suggests the use of UV radiation and crumb filtering to decontaminate the ballast water effectively. He will test the success of these treatments through the use of tanks receiving three separate treatments and one control.
Michael Di Nunzio, “Assessing the Risks Posed by the Chinese Mitten Crab”
In this pre-proposal, Di Nunzio discusses the possible correlation between mitten crab invasion and infrastructure damage in San Francisco. He furthers this exploration to address the possibility of an invasion in other areas with important infrastructure. He proposes to test these questions through a study similar to Rudnick et al. (2000).
Caitlin O’Neill, Determining the Efficiency of Ballast Water Exchange in Reducing Species Spread
O’Neill proposes to study the effectiveness of removing invasive species in the filtering of ballast water during an exchange. O’Neill will study this by recording the percentages and types of species filtered out from the ballast water in the boats San Francisco bay. The exchange method, voyage conditions, size of boats, and other factors will be accounted for in her study.
We as the review panel have chosen to fund O’Neill’s study of ballast water in San Francisco bay. We determined our money would be best invested in this project because the outcomes expected from this project are most beneficial to the science community as well as society as a whole. O’Neill also thoroughly supported the necessity for proper ballast water filtration. We also feel that this study can be effective in convincing the government to further regulate control of ballast water exchange. This pre-proposal was chosen over the other two because O’Neill convinced us of the importance of this issue. For instance, Lockwood’s pre-proposal was not chosen because we did not feel he adequately supported the significance of ballast water treatment. The pre-proposal was brief, leaving room for elaboration. He also had several grammatical errors indicating the proposal should be proof-read. Di Nunzio’s pre-proposal was strong, however, we felt his study would not benefit the scientific community as much as O’Neill’s. Although San Francisco is an area heavily invaded by foreign species , Di Nunzio only focused on mitten crabs. O’Neill’s study will encompass all invasions from ballast water, which includes mitten crabs.
For my literature review topic, I chose to study the effectiveness of UV radiation treatment in comparison to other ballast water treatment methods. In the experiment, the crew of the ship could act as citizen scientists. Before the ballast water is even discharged, some of the ship’s crewmen could test the water before and after the UV treatment has been applied. This would cut the time it would take for scientists to perform the tests at a port, and it would even open up new opportunities in the study, such as allowing the use of UV treatment in combination with the process of ballast exchange. It would be impractical to carry a scientist on board every ship, so there would be no way to test the water gathered from a foreign port before it was released and replaced by sea water.
As for the other methods of treatment, such as biocides, the amateur scientists can record the effect that the chemicals have on the body of water they are applied to. Tests can be taken to determine the chemical content of the water, which would be an important factor in the experiment. Also, citizen scientists could collect the fish before and after the chemical treatment of a certain section of water. The health, size, lifespan and many other factors may be altered by the biocides, so these studies will be conducted to see if the alterations exist, and if they do, to what extent will they affect the native species.
Johanna N. Bradie (2010) from the great Lakes Institute for Environmental Research and her team performed a study on the use of Brine as a ballast water cleanser. All transoceanic vessels that enter the Great Lakes are required to manage ballast water an d ballast tank residuals to help prevent the transfer of non-native species. Bradie (2010) and her team did tests with various concentrations of brine to determine when invertebrate mortality in the ballast water reached 100%. It was found that at 115 brine concentration, a near 100% mortality rate was reached regardless of the temperature of the water. With further testing of ship-scale trials, the authors believe this could be an effective way to cleanse ballast water of transoceanic ships.
Chemical Engineering Journal 156: 305-312 (2010)
Ballast water is carried in cargo ships to maintain stability, but can contain microorganisms (e.g. Phyllorhiza punctata larvae) that have the potential to become invasive species in foreign waters. Researcher Efi Tsolaki from the Technical University of Crete, Greece and others have developed a potential disinfection method to treat ballast water involving electrolysis. The organism being tested was Artemia salina and salt was dissolved in the water to achieve the same conductivity as actual sea water. The electrical disinfection method works by running a current through the tank, which produces hypochlorite and hypochlorous acid from the chloride content in the sea water. These by-products kill microorganisms, and then can be removed from the water by a reduction agent such as sodium thiosulfate. The researchers ran several tests and found that a 135 mA/cm^2 current density held for 1 minute would kill all of the A. salina with minimal residual chlorine by-products of less that 10 micrograms per liter.
The San Francisco Estuary is home to a number of invasive species, often brought there in ships’ ballast water. Ships entering the estuary are now required to undergo ballast water exchange. There are two dominant types of exchange in California: empty-refill exchange and a continual cycling method. Empty-refill exchange requires full exchange at one time while cyclical exchange slowly filters oceanic water through the hull, fully filtering about three times.
Keun-Hyung Choi of the Romberg Tiburon Center at San Francisco State University led a study examining the number of zooplankton in the ballast water of bulk carriers and container ships post-exchange. Samples were mostly taken from topside tanks and then examined to determine the species present.
The study compared the prevalence of zooplankton in boats where empty-refill ballast exchange took place to boats where cyclical exchange occurred. Choi and colleagues found fewer zooplankton in ships that underwent empty-refill ballast exchange, supporting the thesis that that method is more effective.
JOURNAL OF PLANKTON RESEARCH 27, 707–714 (2005)
Marine Pollution Bulletin 54, 1170-1178 (2007)
Aquatic invasive species detrimentally affect the ecosystems they invade. Many invasive species are transported very long distances to environments in which they are nonindigenous in ship ballast water. An experiment on the deoxygenation of ballast water suggests that the control method could cause high mortality rates of aquatic life in ballast tanks.
Tracy McCollin of the Fisheries Research Services Marine Laboratory and his colleagues tested the efficacy of deoxygenating water as a treatment method for eradicating aquatic life in the ballast tanks. The researchers conducted a full scale experiment in actual ballast tanks. They found that the method was effective on zooplankton, however, their phytoplankton results were inconclusive. The deoxygenation method may provide a simple and relatively cheap way to prevent aquatic invasive species from spreading for foreign environments.
Chinese mitten crabs are indigenous to their namesake country of China. However, in the early twenty-first century these crustaceans were introduced to the US west coast where they have become a troublesome and invasive aquatic nonnative species (ANS). It is believed that this crab, like many others, was introduced to this region via the transfer of ballast water used in commercial shipping. Much of the scientific focus regarding ballast tanks concerns international voyages, yet there is surprisingly little research regarding domestic shipping and the secondary spread of invaders.
To investigate this phenomenon Christina Simkanin and her colleagues analyzed ballast water records and ANS occurrence data corresponding to four major ports on the Unites States West Coast. The study found that in 2005 one-third of the vessels arriving at these ports came from other West Coast ports and the overlap of ANS varied from as little as 3% to as much as 80%, suggesting a need for more research.
Marine Pollution Bulletin Volume Number 58, Pages 366-374 (2009)
Biological Conservation 102, 331-341 (2002)
Aquatic invasive species can have devastating effects on the ecosystems they invade. It is well known that many invasive species are transported long distances to foreign environments in ship ballast water. Experiments on the deoxygenation of ballast water suggest that the process could not only lower survivorship of species in the ballast water but also prove cost effective for the ships by lowering the rust levels of ballast tanks.
Mario Tamburri of the Monterey Bay Aquarium Research Institute and his colleagues tested the survivorship of aquatic organisms as well as rust accumulations in oxygenated water vs. deoxygenated water in ballast tanks. They found that rust levels of the deoxygenated water were far less than the oxygenated water and they observed a significant mortality in the deoxygenated water in just a few days. Deoxygenation systems in ships may offer a financial incentive to ship owners as well as significantly reducing the number of aquatic species they transport.