Determining the ability of two approaches to measure eDNA to reliably quantify the abundance of invasive common carp in Minnesota lakes

This project developed and tested the ability of eDNA to estimate the abundance of common carp in Minnesota lakes. This study will complement the eDNA study of Asian carps which focuses on presence/absence measures of a rare AIS. Here, we use the common carp as a model because it is extremely abundant, well understood, and the subject of management efforts.

The primary objective was to determine if we can accurately and reliably measure the abundance of common carp in waters they are known to inhabit. Researchers developed and validated two techniques: quantitative PCR (qPCR) of carp mitochondria (conventional eDNA analysis) and qPCR of microbial rDNA from carp feces combined with sequencing (also known as metagenomics). Metagenomics is promising because it could offer greater sensitivity and more information on species abundance and ecosystem health. Initial efforts identified molecular markers for common carp by comparing mitochondrial sequences from the common carp and close relatives. Quantitative PCR assays were then developed.

In a second step, the effects of key environmental variables on the abundance of these markers were examined in laboratory mesocosms. Lastly, researchers applied the most promising techniques to study the relationship between the abundance of these markers and the abundance of common carp in local lakes.