Spring 2022 eNewsletter

Featured Research: Graduate Research Fellow Update
eDNA as a Powerful Tool for Predicting Species‐Specific Abundance

Kara Andres, Cornell University

Kara Andres, 2021-2022 CIGLR Graduate Research Fellow. Photo Credit: Kara Andres.

Reliable information on the distribution and abundance of invasive species is necessary for understanding their impacts and preventing their spread; however, this information is often difficult to obtain. Molecular techniques such as environmental DNA (eDNA) analysis are being used more readily to census aquatic species, due to improved sensitivity and efficiency compared with traditional sampling methods. While this approach is well established for detecting species presence and biodiversity, the utility of eDNA for predicting species abundance is relatively understudied, particularly in natural systems. Efforts to correlate ambient eDNA concentration with species abundance have been met with moderate success, yet many questions and concerns about the accuracy and interpretation of these results remain, potentially hindering the application of this approach in practice.

Kara Andres is a PhD candidate at Cornell University and 2021-2022 CIGLR Graduate Research Fellow, working with her advisor David Lodge (Department of Ecology and Evolutionary Biology, Cornell University), co-advisor Ed Rutherford (NOAA GLERL), and collaborators Peter Esselman (USGS Great Lakes Science Center) and Jose Andrés (Department of Ecology and Evolutionary Biology, Cornell University) to develop novel eDNA-based metrics of species abundance.

“My research focuses on the prolific Great Lakes invader, the round goby (Neogobius melanostomus),” said Andres. “Our team plans to carry out an intensive field sampling effort to compare and test the performance of image-based eDNA abundance estimates.”

Collecting eDNA samples on Lake Huron. Photo Credit: Kara Andres.

The round goby has impacted fisheries in the Great Lakes and is one of the biggest threats to New York waters. It competes with native fish species and will even eat the eggs of some game fish species. When their numbers are low, the round goby can be difficult to find and collect because of their excellent camouflage with the lake bottom.

“Being able to predict how many round goby individuals there are and possibly where they came from will be helpful if we hope to curtail new introductions at early stages,” said Andres. “With the assistance of scientists from the USGS, I collected eDNA samples from nearshore areas of Lake Michigan and Lake Huron during the summer and fall of 2021. A USGS autonomous underwater vehicle (AUV) was simultaneously deployed at each site, capturing benthic images that will be used to estimate round goby numerical abundance for comparison to eDNA-based estimates.”

While laboratory work and image assessments are still underway, preliminary results show reliable detection of genetic variation in eDNA samples.

“Our goal is to improve eDNA-based estimates of population abundance, giving us a more reliable method to monitor species that are otherwise difficult to observe,” said Andres. “Supporting the use of eDNA as a powerful tool for predicting species‐specific abundance will be useful for assessing invasive species in natural systems.”

About the Author:

Kara Andres is a recipient of a 2021-2022 CIGLR Graduate Research Fellowship and currently a PhD candidate in the Department of Ecology and Evolutionary Biology at Cornell University. This CIGLR fellowship has supported Kara’s research and collaboration with NOAA GLERL and USGS scientists.

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