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Researchers detect invasive species efficiently

Christian Myers | Friday, April 12, 2013


A team of Notre Dame researchers has developed a transportable, two-part system for detecting the presence of invasive species in aquatic environments.

The paper, published in the journal ‘Conservation Letters’ and titled ‘Rapid invasive species detection by combining environmental DNA with Light Transmission Spectroscopy,’ details the team’s recent efforts to test its new invasive species detection process.

Scott Egan, a biology research assistant professor, said the team’s recent efforts have been bringing the processes of testing for environmental DNA (eDNA) and Light Transmission Spectroscopy (LTS) together as a way to detect the presence of invasive species in an aquatic environment.

“eDNA and LTS are separate processes that each work on their own,” Egan said. “The paper is about bringing the two processes together in the field. There are many problems of species detection where we can apply this environmental field diagnostic system.”

According to the paper, this new, rapid, inexpensive and accurate on-site method of detecting harmful aquatic species will help ongoing efforts to prevent their introduction and spread.

Egan said although the paper only focuses on the tests the team performed to ensure the process works, the end goal is for the system to address the growing problem of invasive species.

“In the end, this is intended to solve real problems,” Egan said. “Invasive species threaten biodiversity and the functioning of ecosystems and economies worldwide.” 

A specific example of where the new system could be used is testing ballast water of ships used for buoyancy in the Great Lakes region, Egan said.

“We hope to get this [equipment] on ships coming into our country, into the Great Lakes, and stop the invasions before they start or while the invasive species are in small enough numbers to eliminate,” he said. “This approach lowers the cost to society of protecting our great lakes ecosystems.  It’s much harder to remove species after they’ve begun to spread, and some species are so prevalent now that we can’t get rid of them.”

Egan said the system can be applied to any situation that requires identifying particular organisms in an environment. Egan said the team has talked about using the system to detect disease-causing organisms and other pests, and the process could even be used for terrestrial environments by testing streams or other bodies of water that contain the runoff from the target area.

The testing involved two steps, Egan said. First, the team took water samples from the lakes on campus and seeded them with tissue samples from five high-risk invasive species, and then successfully used their system to detect the invasive species. Second, they took samples from Eagle Lake, which is just across the border in Michigan, and successfully tested for an invasive species of zebra mussels, known to be in Eagle Lake. 

Egan said the process involves filtering all biomaterial from the water sample, extracting any DNA, exposing the DNA to nanoparticles that only attach to particular DNA sequences unique to a certain species, and then using LTS to observe whether or not the nanoparticles have attached to any DNA from the sample.

Egan said the team had to design the nanoparticles, called oligonucleotides, so they would only attach to particular sequences unique to several common invasive species.

“Our procedure was to look for diagnostic species specific DNA variation, which is basically just finding a unique sequence of the A’s, C’s, G’s and T’s of DNA for each species we wanted to detect and then functionalize the nanoparticles that only bond to that particular sequence,” he said.

Egan said so far the team has only performed the DNA extraction and LTS in the lab, but they hope to perform the whole process in the field this spring.

“Each one of the components works and can work in the field, but we haven’t yet done everything in the field. We hope to do that at Eagle Lake this spring,” he said.

The research system was comprised of Egan, Matthew Barnes, Ching-Ting Hwang, Andrew Mahon, Jeffery Feder, Steven Ruggiero, Carol Tanner and David Lodge. Egan said he is from the biology department and works with the Advanced Diagnostics and Therapeutics Initiative (AD&T), but there were other team members affiliated with the physics department faculty and the Environmental Change Initiative (ECI). 

Egan said the interdisciplinary nature of the project and the collaboration of researchers from different disciplines were the best aspects of working on the detection system.

“One of the coolest parts of this project is that it exemplifies the purpose of these initiatives to promote interdisciplinary work,” Egan said. “We have a great mix of scientists coming together to have a real impact on a significant real world problem.”