Although the highly invasive water hyacinth was introduced into Florida over 30 years ago, the aquatic plant hasn’t been nearly as successful as it has been in other places such as Lake Victoria, South Africa. Despite this, Florida’s weather and conditions are optimal for sufficient growth of water hyacinth. The warm climate, high nutrient and light environment is very conducive to water hyacinth growth. Researchers Volin and Soti from the University of Connecticut and Florida Atlantic University sought to test various nutrient and herbivory levels versus water hyacinth growth to see if the specific amount of nutrients and plant removal found in Florida had a negative impact on the water hyacinth. Soti and Volin found that water hyacinth are able to survive under low amounts of plant removal no matter the nutrient level. This suggests the most effective method of removal of the plant is a high level of herbivory. This research gives great insight into future control of the highly invasive plant.
Biological Control Vol. 54 Issue:1 35-40 July 2010
Researchers A. Bradley and John F. Mustard at Brown University have done research on the dynamics of invasive plant species in order to see if more effective land management can reduce the chance of future invasions. Specifically, they studied Bromus tectorum, better known as cheatgrass. Remote sensing was used to track how likely cheatgrass expansion was in relation to how the land was cultivated, elevation, roads and several other factors. There were positive correlations between cheatgrass invasion and high elevation, close proximity to cultivated land, roads and other areas already occupied by cheatgrass. These relationships were used to create a “risk map” for future cheatgrass invasion that can help change the way land is managed for the better. This study shows the importance of including how land is used in methods to reduce plant invasions.
Ecological Applications, Pages 1132-1147(2006)
Ever since this fish’s release into the Atlantic Ocean in the late 20th century, the lionfish (Pterois volitans) has invaded coastline areas from Belize to Massachusetts. Authors Isabelle M. Cote and Aleksandra Maljkovic in their article “Predation rate of Indo-Pacific lionfish on Bahamian coral reefs” demonstrate how these fish are simply taking over many of the reefs in the Caribbean. After doing several Scuba dives off of New Providence Island, Bahamas, the researchers made several important discoveries about lionfish behavior. They saw how Lionfish in the Atlantic mainly feed during the day, unlike the native pacific population that does so at night. Finally, the authors found that the predation rates of lionfish in the Caribbean are significantly higher than the presumed rate in the eastern pacific. This final observation brought the authors to the conclusion that lionfish could be much more destructive than many scholars think. (Cote 2010)
After spreading throughout Europe, Japan, and Australia, it is no secret that the New Zealand mud snails are invasive species. In North America, they have become particularly present in most major Western waterways, with the exception of the Great Lakes. Edward P. Levri and his team from Penn State collected samples at several different depths in Lake Erie to further explore the minute presence of the snails in the Great Lakes. He and his colleagues found three separate areas in Lake Erie where the mud snails had invaded. Overall, however, the findings were relatively modest. The scarcity of the mud snails in the lake can be attributed to depth they were found; it is very unlikely that they have been or will be transportated through recreational activities such as boating. Levri and his team stress that although further invasion is improbable, there is still the possibility that they can spread by dredging, the digging up of sediments, or even more introductions from Europe.
Journal of Great Lakes Research 3, 335-340 (2007)
Journal of Wildlife Management, Volume 73, 1414-1419 (2009).
In recent years, a need for effective ways to exterminate Nutria from regions such as Luisiana marshes has arisen. The most simple method of killing them is through the use of traps. To improve the effectiveness of traps, Susan Jojola, Gary Witmer, and Patrick Burke researched how the use of attractants improved the chances of capturing a nutria. After a controlled study of 14 different possible lures in both a lab setting and in nature, the researchers concluded that a synthetic nutria fur and anal-gland extract was the best formula to attract the animals. The final chemical developed increased the chance of capture by around two and a half times. The use of attractants like the one created was suggested to be used as a cost-effective method to reduce nutria damage.
Environ Biol Fish (2009) 86:389–398
The lionfish (Pterois volitans) is a beautiful saltwater fish native to the Indian Ocean. In the past decade they have been sighted all around the Gulf of Mexico and the Northern Atlantic. James Morris and John Akins of the National Oceanic and Atmospheric Administration (NOAA) decided to collect samples of lionfish and, by examining their stomach contents, identify their diet and any species under threat from this new invader. Samples were collected from a variety of locations, from reefs and canals to mangrove habitats. They focused on two primary statistics. Morris and Akins recorded the frequency and percent volume of a species in the stomach. The diet of the lionfish is about 78% teleosts (a variety of fish) and 14% crustaceans. Another statistic recorded is that lionfish had much larger volumes of food in their stomach between the hours of 8:00-11:00 AM. Based off this data, the teleost variety of fish is most under threat from this aquatic invader.
Eriocheir sinensis, better known as the Chinese Mitten Crab, has become a topic of wide concern in the last few decades. It has spread from the seas of China, through the Thames River and along the coast of England, and into the Pacific coastline of the United States. An ongoing search to find a solution to the spread of this invasive specie has led a team of scientists from the Department of Zoology of the Natural History Museum of London to investigate the possibility of using these crabs as a food source for humans. The team researched the effects of their consumption on human health by measuring levels of Dioxin and PCBs in their meat. The levels of toxins, when compared to guidelines for European Tolerable Daily Intakes, showed that adult men and post-menopausal women would be able to consume meals a few times per week. However, the potential health risk is too great, and another solution must be found.
Environ. Sci. Technol. doi:10.1021/es802935a (2009)
Journal of Great Lakes Research 36(3): 540-547 (2010)
With the help of modern human transportation, invasive species can reach habitats that they never could before. The ballast water of ships carries multitudes of microorganisms that, when discharged into a new ecosystem, can disrupt the natural balance in that area. Experiments done in the Laurentian Great Lakes concluded that assemblage, staining, and observation was the most efficient way to evaluate the freshwater organism content in ballast discharge while other methods proved ineffective and unclear.
Euan D. Revie and his research team from the University of Minnesota Duluth tested multiple ballast water treatments, such as: enzyme digestion, flow cytometry, and multiple stains. A reliable process to test the densities of phytoplankton cells in the 10-50 micrometer range has yet to be found, and reliability was based on several factors. The methods were tested for precision of the organisms’ conditions at ballast water discharge, consistency of results in a given area, and practicality as well as speed of method during on-site projects.
Diversity and Distributions doi: 10.1111/j.1472-4642.2007.00434.x (2007)
In recent years, the Laurentian Great Lakes have been a destination for many invasive species. One of the most recent aliens to enter is the bloody red shrimp (Hemimysis anomala), which is native to the Black Sea. Many scientists wonder how these shrimp got to the United States.
Asta Audzijonyte, from the University of Helsinki, with a team from Finland and Austria, tracked the shrimp using mitochondrial DNA, the gene sequences found the the mitochondria of a cell. The shrimp found in the Great Lakes had most likely come from the Danube delta. The team were able to track the crustacean from the Danube delta, to the Danube River, through the Main-Danube canal, finally to the Rhine delta where the the shrimp could travel to the United States via the ballast water of Trans-Oceanic ships. With this method of tracking, the authors were able to figure out where the bloody red shrimp originated from.
Starting in 1959, the American Bullfrog has been introdouced into most provinces in China, and because of its size and predatory nature, has been able to thrive off consuming the native species. The bullfrog has been known to eat a number of the native anurans, but to what extent has been hard to determine for scientists. Yanping Wang and his team from The Society for the Study of Amphibians and Reptiles, decided to try and determine which prey the bullfrogs preferred to determine the overall effect the bullfrog has. First, they tested which bullfrogs, larger or smaller and male or female, consumed most on a daily basis. Then they determined which of the four main sources of food the bullfrogs preferred and which size. The results of the experiment showed that the though the bullfrogs preferred the smaller species such as the Rana limnocharis but only because of the species generally smaller size compared to the other prey.
Journal of Herpetology. Volume 41, p. 514-520.(2007)