Bythotrephes longimanus, more commonly referred to as the spiny water flea, shown signs of disrupting the crustacean communities of the Great Lakes. Although many studies have shown the negative effects that the spiny water flea can cause on its environment, scientists still debate over whether or not these findings can truly be attributed to this invasive creature. This is why further research into the impacts caused by the spiny water flea still needs to be conducted.

Barbiero et al. (2009) have already presented a good example of the type of research necessary for proving the negative effects of the spiny water flea. Barbiero et al. (2009) analyzed samples collected by thirteen different research cruises in 1986 in Lake Erie. The data obtained from these samples were then compared against samples that were more recently collected. By doing this, Barbiero et al. (2009) were able to produce estimates of the spiny water flea’s impact on the crustacean community over a significant period of time by comparing estimates of cladocera production with estimates of flea consumption.

Barbiero, R.P., Rockwell, D.C. 2008. Changes in the Crustacean Communities of the Central Basin of Lake Erie during the First Full Year of the Bythotrephes longimanus Invasion. Journal of Great Lakes Research 34:109-121.

Journal of Applied Ecology 47, 273-280 (2010)

In an ideal scenario, invasive species management should be based upon an understanding of the invader’s ecology in its new environment; the fact that most attempts to control invasive species have ended in failure is a cue that new approaches are desperately needed.  One possibility involves identifying ecological and behavioral “mismatches” – ways in which the characteristics of the invading species render it vulnerable to some mortality source operating within the introduced range.  Exploring such “mismatches” could lead to novel control opportunities.  The invasive cane toad, Bufo marinus, is an exemplar of the success of this method.

Georgia Ward-Fear et al. of the University of Sydney found that in the Australian ecosystem (in which the cane toad is an invader), high desiccation (or dehydration) rates restrict newly transformed (metamorph) cane toads to the margins of water bodies, rendering the metamorphs vulnerable to predatory ants (Iridomyrmex reburrus).  By adding bait (cat food) to selected areas, the research team was able to capitalize on this evolutionary shortcoming and increase ant densities (and thus, toad mortality) by more than four-fold in these areas.  In fact, over 50 % of attacks by ants in the field were immediately fatal.  Thus, manipulating the foraging locations of ants towards the margins of water bodies maximizes successful predation, targeting toads when they are at their greatest disadvantage.

In 1998, Edward P. Levri from Indiana University studied the how effects the parasite Microphallus has on the behavior of New Zealand mud snails impacts the New Zealand fish, Potamopyrgus antipodavun. The design of his experiment included collecting fish samples from various hours of the day, particularly morning versus evening, and counting the number of infected snails compared to non infected snails. He was able to count the snails present in the fish by first killing them and then examining the guts. Levri found that the fish guts tended to have a significantly higher amount of uninfected snails than infected. These results showed that the behavioral changes the parasite caused the snail made the fish less likely to be in the water during times where the fish population was feeding. These findings show that the parasite does not have a secondary impact on the New Zealand fish.

Oikos 81, 531-537 (1998).

A study was done on the juvenile Chinese mitten crab and its interactions with the native crab in the Thames estuary, the Carcinus maenas by Victoria Gilbey, Martin Attrill, and Ross Coleman of the Marine Biology and Ecology Research Centre of the University of Plymouth. It was found that there was no difference in the number of crabs found in high and low shore levels. The mitten crab distribution correlated with the amount of shelter present, shelter that the native C. maenas also used. The mitten crab directly compete with the native crab species and it was found in a lab that the Chinese mitten crab successfully excluded the native crab of a similar size from a mutual refuge, regardless which crab initially inhabited the shelter. This study illustrates part of the reason that the mitten crab is able to invade estuaries so well; they directly out compete the native species.

Biol Invasions (2008) 10:67-77

Following the invasion of the northern snakehead, Channa Argus, in multiple ponds and rivers in a handful of states, a lot of debate has been centered around the state government’s decision to apply the poison rotenone into the invaded bodies of water.  The decision was hotly contested because there was uncertainty about rotenone’s long term effects, especially in rivers, where the poison could float for tens of miles down stream.  A five year study, conducted by Frederick Magnum and J.L. Madrigal, set out to test the long term effects of rotenone when applied to a river.  Ultimately, the collected data encouraged Magnum and Madrigal to conclude that the rotenone application in rivers can effectively accomplish its purpose, if done properly, but can also lead to unwanted potential long term changes in aquatic species stability and composition.  But the latter has the ability to be adverted if constant, thorough monitoring is conducted to ensure the post treatment ecosystem mimics the pre treatment ecosystem.

Frederick Magnum, and J.L. Madrigal.  Rotenone Effects on Aquatic Macroinvertebrates of the Strawberry River, Utah: A Five-Year Summary. Journal of Freshwater Ecology.  Volume 14, Number 1 (1999).

doi:10.1016/j.marenvres.2010.08.003

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.

Biological Invasions DOI:10.1007/s10530-010-9786-8 (2010)

With the increase in number and variety of harmful invasive species, the development of ecological modeling methods has become increasingly useful.  These models are created to show ecological needs of the invasive species at question, and show what conditions are necessary for the species to continue to grow.  James A. Morris, Kyle W. Shertzer, and James. A. Rice, members of the National Oceanic and Atmospheric Administration in North Carolina, have created a model of the growth rate of lionfish in the Atlantic and Caribbean.  They used sensitivity analysis of vital rates of these lionfish, which allowed them to determine that the successful growth of lionfish populations is heavily reliant on the survivability of larval lionfish.  The models that they created are important in that they shed light on a possible way to eliminate lionfish growth.  According to their findings, stopping the spread of lionfish would involve removing over a quarter of the adult population on a yearly basis.  However, if humans could develop a response plan that specifically targeted lionfish larvae, there may be a chance to finally stop this harmful invasive species.

Fisheries 33:122-129, 2008
Several studies suggested that water hardness has a significant effect on the viability of carp eggs. Since a carp invasion depends upon the success of initial egg incubation and hatching, the observation on the viability of carp eggs can be useful in predicting the potential risk of an invasion. Whittier and Aitkin (2008) from Oregon State University predicted the potential distribution of silver carp using water hardness data from over 3000 streams and rivers across the United States. They found out that the majority of current silver carp active areas lied within hard-water regions, with a few exceptions of soft-water regions where water still originated from hard-water sources. They stated that this finding lend support to Gonzal et al., whose study hypothesized that carp eggs could hardly survive soft water. They claimed that the study might be a good news to New England, the Southeast, and the Columbia River and Snake River basins. Whittier and Aitkin called for further laboratory study to verify this hypothesis and to evaluate whether the results are applicable to bighead carp and other Asian carp species.

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.

Dr. Judy F. Shearer and Dr. Michael J. Grodowitz, from the Aquatic Nuisance Species Research Program, wrote a report on predicting whether an invasive species has the potential to spread based on the use of environmental tolerance data. Environmental tolerances give a range of values for which an aquatic species can maintain and survive. In this study several methods used in predictive ecology were highlighted but the focus of the report was on the zebra mussel and a zebra mussel calculator that has been developed. The calculator calculates the vulnerability of a certain area to zebra mussel invasion. The calculator has built in environmental tolerance data on five different variables. The variables are calcium content, dissolved oxygen, temperature, salinity, and pH. The calculator accepts values for all five parameters but it only needs information on three to predict vulnerability. The likelihood of invasion is based on the score produced by the calculator. A score below 3 is low risk, from 3 up to 7 is medium risk, and 8 to 10 is high risk.

References:

Shearer, J. F., and M. J. Grodowitz. 2010. Predicting the potential for invasive species establishment by using environmental tolerance data. ANSRP Technical Notes Collection. ERDC/TN ANSRP-10-2. Vicksburg, MS: U.S. Army Engineer Research and Development Center. http://el.erdc.usace.army.mil/ansrp/ansrp.html.