Using Environmental DNA (eDNA) to Improve the Accuracy and Efficiency of Managing the Invasive Pacific Red Lionfish in the Caribbean
The Pacific Red Lionfish (Pterois volitans) was introduced to the Atlantic Ocean in the 1980’s. Since their introduction the lionfish have rapidly spread throughout the Caribbean and the Gulf of Mexico, posing a serious threat to marine ecosystems throughout invaded regions. Lionfish have a high reproduction rate, as females can lay approximately 2 million eggs per year per individual. Lionfish are capable of consuming up to 20 fish in half an hour, and can reduce native fish populations by up to 80-90%. The high reproduction rate of lionfish, in combination with their aggressive appetite, lack of predation, and generalist behavior gives the lionfish competitive advantages in the areas they invade. The indiscriminate diet of the lionfish is problematic because many of their prey are herbivorous reef fish. Herbivorous reef fish help maintain coral reef health by consuming algae which, if left unchecked, would grow over the coral polyps, blocking the sunlight from getting to the symbiotic organism found in the coral, resulting in coral death and further biodiversity loss.
Current methods used to monitor the Caribbean lionfish invasion rely extensively on visualizing lionfish, the most common being visual surveys. These techniques are prone to inaccuracy (e.g., false sighting claims), are time and labor intensive, and can be financially costly. The dependence on these traditional management techniques greatly limits the effectiveness of managing this aggressive invasive species that is drastically altering coral ecosystems.
The goal of this study is to improve the efficiency and accuracy of managing lionfish by implementing the novel technique of using environmental DNA (eDNA) to confirm the presence of lionfish in a marine environment. eDNA has becoming an increasingly popular ecosystem management tool because it offers a unique, molecular alternative to the current methods used to monitor for organisms. Instead of visualizing the often elusive and nocturnal lionfish to determine its presence, water samples are taken from sites of interest and analyzed for lionfish DNA left behind in the water (e.g., scales, excrement, fish slime, etc) using standard molecular techniques (i.e., DNA extraction and PCR).
Our results show how the use of eDNA methods have the potential to reduce the time, money and labor required to conduct lionfish surveys. In addition, our lab studies showed that lionfish eDNA concentrations correlated with abundance even as density was held constant; however, viable eDNA persist in the environment for less than 48 hours. Processing an eDNA sample costs approximately $0.05, and numerous samples (1-50) samples can be run in <12 hours. Overall, our study shows that eDNA is an accurate and cost efficient methodology in detecting the presence of the invasive lionfish compared to traditional sampling.
Our study suggests that eDNA could be an effective management tool for monitoring the spread of the lionfish invasion in the Caribbean. This study will also exemplify the utility of eDNA for the monitoring of other marine invasive and endangered species.