Aquatic Invasive Species

Options for Refining Ballast Water Treatment Protocols Will Arise Pending the Results of a Proposed Study:
Ship ballast water used to maintain the stability and structural integrity of the vessel has long since been linked to the spread of non-native species across the globe. When a ship takes cargo, its ballast water is discharged to offset the additional weight of the cargo. An unintended consequence of this discharge is the subsequent release of non-native species into the port where the ship is docked. Invasive species have been associated with health risks and ecological and economic effects. The estimated cost of invasive species damages exceeds 138 billion dollars in the United States (Tsolaki et, al., 2009). Rapid growth of the shipping industry has further facilitated the exchange of not only consumer goods but also species “stowed away” in ships’ ballast water. Over 80% of the world’s goods are moved by shipping accounting for the transfer of 10 billion tons of ballast water annually (Boldor et. al., 2008). As the shipping industry cannot be expected to reduce its’ scale or operations, steps must be taken to ensure that ballast water is not carrying potentially harmful invasives.

Several methods exist for the elimination of species taken in with ballast water thereby eliminating the risk that these species are introduced into foreign environments. Port-based treatment involves treating the ballast water in portside treatment facilities requireing that the ballast water be pumped out of a ship’s tanks before it is treated. Shipboard treatment involves treating the ballast water onboard the ship using physical methods (filtration), mechanical treatments (microwave heating or ultraviolet light), or chemicals (biocides, chlorine, ozone, and hydrogen peroxide) (Tsolaki et. al., 2009). All of these methods vary both in removal efficiencies and cost. To determine the best option for ballast water treatment, Kevin Shia has proposed a study to evaluate the best method of ballast water treatment. Working under the research questions “can ballast water treatments reduce a significant number of foreign species while being environmentally safe and inexpensive? Will port-based or shipboard treatment be the most successful at removing the majority of foreign species?” (Shia, in production), Shia hopes to determine a protocol for the effective and cost-efficient treatment of ballast water. Shia expects that both port-based and shipboard treatments will significantly reduce the number of invasive species in ballast water further asserting his conviction that shipboard treatments utilizing mechanical separation will be the safest, most economical, and efficient. In order to test this hypothesis, Shia proposed a study of species populations in ballast water on one trade route. After taking initial tallies of species found in ballast water, Shia will test 5 port-based treatments, and 9 shipboard treatments’ (3 mechanical, 3 chemical, and three combined) effects on species populations in ballast water. Shia will utilize DNA testing to indicate the presence of species in ballast water. A main goal of the study is the establishment of an effective ballast water treatment protocol to reduce the number of species found in ballast water. The study should provide information on the economic and environmental cost of each treatment method with respect to its effectiveness for removing invasives. The results of this study will also be directly applied to industrial engineering. Better information on ballast water treatment methods allows engineers to make decisions when designing both ships and ports. In this way, the negative effects of invasive species can be mitigated through the installation of efficient, inexpensive, and environmentally safe ballast water treatment systems in ports and on ships.

DURHAM, NC — The killer shrimp (Dikerogammarus villosus) is one of many species worldwide that has expanded beyond its native habitat and become known as an aquatic nuisance species.  Originally found only in central-eastern Europe, it has invaded waterways throughout the continent, where it attacks and eliminates native gammarid species.  With large, powerful mandibles, the killer shrimp is capable of consuming a variety of prey and outcompeting other amphipods.  It gets its name from its destructive behavior, killing far more prey than it can eat, and has even been known to attack small fish.  Within a short time after invading a new area, it can eliminate a wide range of species from the ecosystem, drastically altering the interactions of the food web.

At present, there have been no reports of killer shrimp in North America.  However, the transportation of this destructive invader to the U.S. is not out of the question, as everyday thousands of gallons of foreign water are brought into the country through the ballast water of ships.  This is one of the most common means by which species are transferred between continents, and has been responsible for countless aquatic invasions in the past.

In hopes of preventing the establishment of a killer shrimp population in the U.S., Bernard Jiang of Duke University has proposed a study to test the effectiveness of ballast water treatment on killer shrimp.  Jiang’s study will examine the four main types of ballast water treatment: mid-ocean ballast water exchange, biocides, heat treatment, and filtration, in an attempt to determine which is best suited to eliminating the shrimp from a ship.  Jiang intends to use tanks of water to simulate a ship’s ballast container, controlling temperature, salinity, oxygen level, and all other abiotic factors.  The researchers will put live shrimp specimens at every stage of life into the tanks, perform one of the treatment methods on each tank, and record the number of live shrimp still in each of the tanks after treatment.

The goal of this study, according to Jiang, is “to determine which ballast water treatment is most effective at controlling the shrimp”.  This in turn, he elaborates, “will help prevent the spread of killer shrimp, and will also provide insight into the effectiveness of treatment methods in general”.  There have been previous experiments testing the relative effectiveness of different methods of ballast water treatment, but this would be the first study to focus specifically on killer shrimp.  As such, it would provide species-specific results that would suggest the best way to prevent the introduction of the shrimp into the U.S., explains Jiang, as well as contributing to the general body of knowledge regarding ballast water treatment as a whole.

According to the researchers, killer shrimp should be one of the main priorities targeted by invasive species policy creators, as it could “cause unprecedented amounts of damage” if introduced, yet there is still the possibility of preventing it from doing so.  “Killer shrimp have only appeared on the invasive species radar in the last decade,” says Jiang, “but they have been particularly effective in their invasiveness.”  For this reason, he argues, it is essential that research be done immediately to determine how best to keep the shrimp out of North America, while there is still the chance to do so.

In an age of rapid globalization, the world seems to grow smaller as transportation becomes easier. However, humans are not the only ones that can now travel great distances; sneaky invasive species have the ability as well.

The treatment of ballast water stands as a critical issue in today’s society. Ships take on ballast water for improved stability at sea, but when they arrive at their destinations, they release this water. If it is not properly treated, there is high probability of new organisms being introduced into non-native marine ecosystems. Many aquatic invasive species have been introduced this way.

While different methods of water treatment exist such as filtering water or using chemical agents, these methods are not completely effective. Filtering allows smaller organisms to pass while releasing chemically treated water creates a negative impact on the local ecosystem.

A relatively new method of ballast water treatment involves deoxygenation. This technique involves pumping nitrogen gas into the water to displace most of the oxygen. A low oxygen level then kills most of the oxygen-dependent organisms. In addition to offering a new approach to water treatment, this method appears to be safe for the environment and actually reduces the cost of shipping due to less tank corrosion.

Any method is not without its faults; deoxygenation requires certain unique equipment and current research into this topic suggests that some species require up to three days to kill. This time period may be too long to be of use. Like the other techniques, treating ballast water may not fully eliminate all organisms as well. Many questions remain unanswered.

Andrew Ang of Duke Unversity is conducting a study to determine how effective deoxygenation is and whether it can serve as a viable method of ballast water treatment. In his experiment, he will simulate deoxygenation of a ship tank that will contain common aquatic invasive species such as zebra mussel and types of algae. Also taken into account will be the juvenile versus adult types of organisms.

Only a proper assessment of deoxygenation will reveal its efficacy as well as its cost. The results of this study will be used to determine if deoxygenation is a realistic, viable alternative. Andrew Ang states that it is a “promising alternative.”

A collaboration between  the Monterey Bay Aquarium Research Institute in California, and Sumitomo Heavy Industries in Japan report on a new, cost-effective method for treating ballast water. The method, deoxygenation, involves the removal of oxygen water from ballast water using nitrogen gas. Oxygen levels can be reduced to levels less than 0.5%. While deoxygenation prevents the spread of aquatic invasive species by killing oxygen-dependent organisms, the low oxygen levels also reduce ship corrosion, providing an economic benefit to the shipping industry.

Taburri M, Wasson K, Matsuda M. Ballast water deoxygenation can prevent aquatic introductions while reducing ship corrosion. Biological Conservation, Volume 103, Issue 3,  March 2002.

Vol. 210: 139–148, 2001

Ballast water is a leading vector for the spread of invasive species across the world. Thousands of species are transported across the globe daily. There are many different treatment options that are always being evaluated for efficacy and new ones are being developed.

T.F. Sutherland and colleagues at the Fisheries and Oceans Canada Institute conducted a field study that measured the survivorship of plankton in ballast water based on the type of treatment used. They tested one filtration system, with the sample being pretreated with ultraviolet rate and one without being exposed to UV. They then compared the growth rate of phytoplankton during the different situations. They found that the growth of phytoplankton in UV-treated samples was stopped, while those in other treatments still exhibited growth. They concluded that UV has potential to stop growth in ballast water and that future studies should be done on UV treatments.

Ballast Water Technology

Wiley Interscience DOI 10.1002/jctb.2276

Invasive aquatic species have been a major economic and environmental problem worldwide. They are spreading due to the assistance of transport ships that trade throughout the world and transfer foreign species. This is due to the invasive species’ adaptability to many environments, their lack of predators in new environments, and their quick reproduction rates. Therefore, control efforts must be implemented in order for invasive species to stop spreading globally.

Ballast water treatments such as filtration, microwaving the ballast water, and using ultraviolent light are being explored. These studies done by Evan Diamadopoulos and Efi Tsolaki have shown that over 70-90 percent of various species are removed during the process. This could lead to a dramatic decrease in the number of new species emerging in various locations throughout the world, thus preventing new outbreaks that could potentially alter habitats and harm native species. Before these treatments can be put into effect, research must be done to make sure they are environmentally safe.

Lodge et al. (2006) identified six different actions that should be taken by the United States government in order to improve invasive species policy. The first one is to use new information and practices to better manage commercial and other pathways to reduce transport and release of potentially harmful species. I think this is one of the most important factors in policy making. If you do not stop the spread of invasive species, it does not matter how much money or effort you put in to trying to clean them out of one area because chances are they will be back. One pathway that policy needs to deal with is shipping traffic. It is one of the most active pathways and it has the potential to spread millions of species per day. Lodge discusses this issue in his paper and he makes additional recommendations. He talks about how there needs to be more enforcement of existing policies in the US. Also, new technologies available for species detection and removal need to be implemented more than they are. Finally, while a lot of countries, including the United States, have developed regulations for dealing with ballast water, they cannot be fully effective until there is and international standard and uniformity. The International Maritime Organizations (IMO) has come out with some regulations and recommendations, but the issue is that while most countries are adhering to these, they are still vague and leave a lot of room for countries to make their own decisions. The differences that arise in policies from this can cause the measures taken against the spread of invasives not to be as effective.

Lodge, D.M. , S. Williams, H. MacIsaac, K. Hayes, B. Leung, L. Loope, S. Reichard,

R.N. Mack, P.B. Moyle, M. Smith, D.A. Andow, J.T. Carlton, and A. McMichael.

Biological invasions: recommendations for policy and management (Position Paper for

the Ecological Society of America). Ecological Applications 16:2034-2054.