Fighting an Invasion

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Student Research Helps Contain Invasive Species

UMD environmental science senior Erica Strom has a passion for biology and environmental science and a love of the outdoors. Strom is helping preserve the environment through an undergraduate research project (UROP) conducted with Associate Professor Donn Branstrator. Alongside graduate student Mike Sorensen, she is helping to lessen the effects invasive species have on Minnesota waters.

 

SCSE senior Erica Strom, along with graduate student Mike Sorensen, is conducting research which will impact efforts against invasive zooplankton.  
Environmental science senior Erica Strom conducts research to aid the effort against invasive species.  
   
A space of concrete and stainless steel, Strom and Sorensen’s lab space is pristine, sterile. On the walls are diagrams and depictions of various tiny aquatic creatures. On the tables rest microscopes, containers of pond water, and objects of various scientific purposes. A soft, ever present hum echoes from a side room, where a large refrigerator keeps research samples of zooplankton in a controlled environment.

Under one microscope, inside a shallow bowl of water, ‘swims’ a small, strange animal. It stumbles its way through the water on two stick-like appendages. “This is the species of zooplankton I’ve been researching, Daphnia magna,” Strom said. “Like many zooplankton, it has a helpful place in the food chain as prey for larger aquatic life.” Daphnia’s place has come under pressure due to the presence of another species of zooplankton, the invasive Bythotrephes longimanus, (spiny water flea).

Fighting the Invasion

“The spiny water flea is an invasive species that has found its way to Minnesota and populates many of the same lakes as Daphnia,” Sorensen said. “It preys on Daphnia extensively, making it hard for native fish that rely on Daphnia as a food source.” Sorensen is researching the conditions in lakes which house spiny water fleas, in order to streamline prevention efforts against the species. “We are trying to set realistic guidelines that any number of government and non-government organizations, such as the DNR, could use to predict which lakes may make a suitable home for spiny water fleas.” Sorensen explained. "Since there is no reliable way of eradicating spiny water fleas once they have established in a lake, we focus our attention on limiting the further spread of spiny water fleas. The data we are generating will provide a means of prioritizing which lakes may be considered high-risk of a spiny water flea invasion."

Strom’s research is similar to Sorensen’s, but focuses on Daphnia instead. Both researchers are using a similar method of experimentation to find their results. “We collected samples of water from area lakes,” she explained. “To simulate conditions in lakes with different oxygen levels, nitrogen was added to the water which pushed oxygen out. That water was then added to containers seeded separately with Daphnia and spiny water fleas, and their survival rate was documented for the different levels of oxygen.”

Research with Results

The gathered data illustrates why spiny water fleas thrive in deep, cold lakes such as Lake Superior, and struggle in shallower, warmer environments. “Deep, cold lakes like Lake Superior generally have high oxygen levels,” Sorensen explained. “When the oxygen levels of test environments were low, spiny water fleas couldn’t survive.”

Water Flea Daphnia, a common zooplankton which falls prey to the spiny water flea, putting ecosystems in danger.  
The spiny water flea Daphnia  
     
Strom’s research discovered that the Daphnia were able to survive in conditions with lower oxygen levels than spiny water fleas. This is a good sign for conservation efforts, and indicates that Daphnia can potentially survive an infestation of spiny water fleas, by migrating to deeper, less-oxygenated regions of the lake. This does not, however, mean that the invasive predator will not have an impact. “Though Daphnia can survive at lower oxygen levels than they normally inhabit, there are negative effects of doing so,” Strom clarified. It would reduce the potential population growth and renewal, and would adversely affect the health of individual Daphnia.

A Path to the Future

The experience gained through their research will help Strom and Sorensen traverse the path from undergraduate and graduate student to graduate student and professional scientist.

Sorensen wants to work in a position that allows him to conduct scientific pursuits on multiple levels; monitoring and researching lakes, resources permitting and regulation, and educating the public. “I think there is a gap between the science community and the general public on issues related to water resources,” Sorensen said. “I would like to use my passion for teaching to spread public awareness on environmental issues, such as aquatic invasive species.”

Strom plans to work for a year or two before continuing on to grad school. She hasn’t yet decided on a field of work, but wants to do something active. “I want to do something that gets me outside and doing a variety of things, rather than sitting in an office every day.”

Strom travelled to local lakes this winter to collect water samples for research water samples from local lakes provided the most accurate portrayal of native ecosystems Using nitrogen, the oxygen level of the water samples was changed, to test the heartiness of spiny water flea and daphnia in low-oxygen environments. Research specimens were then added to this water back in the lab. Strom analyzes data generated from her research.
Strom traveled to local lakes and collected water samples. These water samples were brought to the lab for testing. Nitrogen was added to those samples to modify the oxygen content . . . and native and invasive zooplankton were added to those samples. Data indicates that spiny water fleas cannot survive in low-oxygen environments.

Prospective UMD students should view the undergraduate or graduate application pages. Current Undergraduates can conduct research of their own through UROPs. To learn more about biology and the rest of the sciences, check out the SCSE homepage.

UMD Those who can Duluth

Written by Zach Lunderberg. April, 2015.

UMD News Articles | News Releases
Cheryl Reitan, creitan@d.umn.edu


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