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.

Eurasian milfoil (Myriophyllum spicatum) has invaded many regions throughout the United States. This aquatic weed has interrupted the ecosystems of lakes and rivers spread across 44 states, covering water surfaces to the extent that prevents swimming and clogs motors. According to researcher Jonathan Marks, it even affects the real estate market, causing property near invaded waters to drop 10%.
These problems have motivated many to control milfoil populations; there are three major techniques used. Physical control entails the act of removing the weed by hand or placing benthic barriers, dark sheets that block out sun, over populations. Others use poisonous chemicals to kill populations of milfoil. Certain weevils, small bugs that eat milfoil, have also been employed to kill milfoil. Weevil populations remain over time, providing long term control. “Although many efforts have been made using these types of control, nobody has truly tried combining methods to attain more effective control,” stated Jonathan Marks. He is experimenting with such combinations, striving to determine if control efforts could be coordinated to be more efficient.
Because Eurasian milfoil has recently entered the Great Lakes region, Marks will be simulating that environment for his experiment in the Sam Parr Biological Station in Illinois. He will use Milfoil weevils for biological control, Triclopyr for chemical control, and benthic mats for physical control. He will use six 800 gallon outdoor ponds to combine control methods in the four possible ways and to use the other two as control ponds.
If Marks is able discover a more effective way to control Eurasian Milfoil, the weed may not be such a persistence nuisance anymore. He expects the chemical and physical combination to have the most synergistic effects, because both of those techniques may undermine biological control. He also anticipates interesting results from the combination of all three control methods. Although the techniques do not represent all of methods of control, they should indicate whether synergistic effects are strong enough to make combination effective enough to outweigh the cost of multiple controls.

DURHAM, NC-

Recreational fishing is a multi-million dollar industry and a popular recreational pastime for many Americans. This tradition, however, may be threatened by the introduction of didymo (Didymosphenia geminata) to trout spawning areas. Tom Atwood is spearheading an effort to learn more about the effects of this species on trout eggs. Didymo, “an aquatic nuisance species” forms thick mats on the bottoms of rivers and other waterways. This species attaches itself to rocks and plants along the bed of the waterway, “making its presence ubiquitous on river bottoms” says Atwood.

The spawning habits of trout involve laying nests of eggs called redds on the bottom of riverbeds. The success of these eggs depends on the water hydraulics surrounding them. Atwood believes that the growing presence of didymo in streams will interfere with these hydraulics, leading to inhibited egg growth. This is an example of a trophic cascade or when the primary producer in a system disrupts a food chain so that the top-level predator is affected. Atwood explains that in this case, the top-level consumer being affected is the adult trout. He intends to test his hypothesis and has submitted a research proposal addressing with the issue.

Atwood’s research would involve the establishment of several experimental troughs. These would be created to simulate the environment of a typical river and redd. Trout eggs of the genus Salvelinus and Oncorhynchus will be added to the troughs. Each collection of troughs will also have a certain amount of didyo ranging from none at all to a heavy cover. Aspects of the water such as initial water velocity, oxygen concentration, fine sediment level and surface water-groundwater exchange would be continuously monitored in each trough. At the end of the study, egg mortality and successful hatches will be counted and compared to the presence of didymo. With this information, Atwood hopes to answer basic questions about the influence of didymo on water hydraulics and how it affects trout redds in nature.

The results of this study will be of prominent concern to recreational trout fishermen throughout the United States. It will educate these citizens about the threat that didymo poses to their game fish and compel them to be more cautious about unintentional invasive species transfer.  The study will also elucidate the effects of didymo on the various trophic levels present in a stream ecosystem.

Alexander Groszewski

Since its introduction in 1935, the non-native Cane Toad (Bufo Marinus) has become a significant threat to native organisms in Australian ecosystems.  Cane toads are large, highly toxic, and are currently spreading widely to many Australian ecosystems.  Furthermore, they are highly poisonous at all stages of life, so they pose a serious threat to native birds and mammals and are taking over many habitats of native reptiles.  As of late however, much government subsidized research has been done with a focus of controlling the surging cane toad population.  One plan that stands out on the forefront of the research involves the use of larval alarm pheromones to slow Cane Toad population rates.  This pheromone is produced by Cane Toad tadpoles when they feel threatened, and studies have shown that the exposure of Cane Toad tadpoles to the pheromone are about half as likely to reach adulthood.

One specific researcher who is at the  forefront of Cane Toad control research is Ben Berg of Duke University.  According to Berg, one of the main issues that scientists have with using the larval alarm pheromone is the fact it is unknown as to why Cane Toad tadpole survival rates are lowered when exposed to the pheromone.  Because of this, Berg is proposing to conduct research focusing on precisely how the pheromone affects Cane Toad tadpoles.  When asked why he thought his research would be pertinent Berg replied that, “it is impossible to know if the pheromone is safe to use as a control agent unless we know what is physically happening to the tadpoles.”  Therefore, Berg’s study will focus on discovering in what way the larval alarm pheromone lowers tadpole survival rate and, additionally, if this pheromone could similarly affect native anura.

Basing his research off of studies done prior by Hagman and Shine, Berg is proposing to see how the larval alarm pheromone affects Cane Toad tadpole survival rate, specifically focusing on its affect on Cane Toad feeding rate.  Berg intends to collect Cane Toads and nine different anura which are native to Australia, all in tadpole form.  Each species will be placed in either a control tank or a treatment tank in groups of ten.  A 50ml dose of the pheromone will be placed in the treatment tanks once per day (the pheromone will be extracted by manually crushing Cane Toad tadpoles and putting the mixture through a filter.  The tadpole food source, algae, will be replaced periodically to make sure there is always sufficient food.  Feeding rates will be taken by comparing the concentration of algae initially in the tank with the concentration of algae in the tanks at set times throughout the day.  This data will be used to model the feeding rates of the tadpoles in control tanks to feeding rates of those in the treatment tanks.

Regardless as to whether or not this study yields savory results, Berg is sure that it will be integral in determining whether or not the use of pheromones is a good way to control the invasive Cane Toad population.  If the chemical is seen to be harmful to only Cane Toads, then it will bolster Hagman and Shine’s claim that pheromone control is the best way to keep the Cane Toad population in check.  If the pheromone is harmful to both species, then the further use of the pheromone will be discontinued.  If no correlation is seen between exposure to the pheromone and feeding rates, then it can at least be said that the pheromone has no effect on feeding rate, which will hopefully spur continued research on the subject.

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.

PLOS ONE doi 2008

Southern Florida has been overrun by invasive python species. Native to Southeastern Asia, Burmese pythons (Python molurus) can grow up to eight meters long. They were introduced into the Everglades region by pet owners whom no longer could keep them. They have since established substantial populations in the region and may spread further.

R. Alexander Pyron, Frank Burbrink, and Timothy Guiher evaluated data from the Burmese python’s native range to determine the habitats in America suitable for its growth. They used ecological niche models based on presence localities with climatic datasets. Because the Burmese python has preference for swampland or similar semi-aquatic niches, there is little likelihood it can establish populations anywhere north of its current location.

Wetlands 20, 280-299 (2000)

The spread of Phragmites australis, common reed, throughout Gulf and Atlantic Coast marshes has been virtually unstopped since its introduction in the late 1930’s. Because of Phragmites’ rapid spread, in areas such as the Chesapeake Bay, its current distribution and colonization rate is unknown. Dan Rice and colleagues at the University of Maryland used a geographic information system (GIS) to gain greater perspective into Phragmites distribution and colonization in three tidal freshwater and four brackish marshes in the upper Chesapeake Bay. Survey results indicated the presence of Phragmites at all seven sites. Using geometric growth formulas, rates of increase for each Phragmites stand were calculated. Older, more established stands have reached equilibrium while newer stands have increasing rates of growth. Rice et. al.’s results seem to suggest that there are limitations to the spread of Phragmites despite its prolific nature.

Scott Rong

Professor Cooke

Writing 20

19 March 2010

In Biological Invasions: Recommendations for U.S. policy and management, Lodge et. al (2006) on behalf of the Ecological Society of America recommends that the federal government undertake the following measures.  Firstly, the federal government must use new information and practices to efficiently manage commercial and other pathways, in order to reduce transport and release of potentially harmful species. Secondly, the government must assess risk through more quantitative measures and must apply said measures to every species importation into America. Thirdly, the United States must use cost-effective diagnostic technologies to increase active surveillance and share information regarding invasive species to create more effective responses to invasions. Fourthly, the government must create legal authority and provide funding to support rapid responses to initial invasions. Fifthly, the government must also provide said funding and incentive for cost-effective programs to gain the popularity of the public and slow the spread of existing species in order to protect pristine environments as well as preserve social/industrial infrastructure and human welfare. Lastly, the government must establish a National Center for Invasive Species Management to coordinate and lead improvements regarding policy. I believe the points made by Dr. Lodge have very immediate importance. Similar measures taken in countries such as New Zealand have enjoyed great success, whereas current invasive species policy in the United States is infantile in its effectiveness. Support for his recommendations in both the political and public sector will certainly reduce the detriment of the “billion dollar problem.”

Invasive species policy and management has just started growing in awareness over the past few decades.  The increase in invasive species is a growing global concern that is costing U.S. taxpayers billions of dollars.  For instance, zebra mussels alone cost $3 million annually.  This $3 million escalades, and deeply impacts our economy.  Lodge et al. (2006) has recommended six actions that the federal government should take; 1) Use information and practices to reduce the transportation of invasive species, 2) Develop a quantitative process for risk analysis, 3) Use cost-effective technology for the sharing of invasive species information, 4) Provide emergency funding to high risk areas, 5) Provide funding to programs that control already existing invasive species, and 6) Establish a National Center for Invasive Species Management.

One of the most important things to remember is early detection.  Through early detection and rapid response, the prevention of invasive species greatly increases.  If an invasive species already exists, the key is control and slowing the spread of the alien species.  The last and final resort to invasive species is adaption.  We must change our behavior of invasive species and bear the financial burden that they leave on us.  Looking at these options, prevention and early detection are the clear solution to these problems.

Frank Chang

The most important aspect of invasive species policy is public awareness. If the people do not support certain legislation, it will be hard to pass and remain as policy. For this reason, the goal of scientists should be to convince the public of the issues at hand, who then in turn help convince the policy makers to produce effective legislation. For example, the Burmese python could never have established itself in the everglades if the public had been properly warned of the consequences of releasing such a pet into the wild.
Lodge sees the politicians as the failures because they have not collectively acted with others outside of their state. However, politicians in areas with weaker regulations have no desire to increase regulations if they do not believe that is what their citizens want. Therefore the goal should be to convince the public that more intensive regulations are needed.