Crayfish eDNA

Campuses: UCLA

Collaborators: Mountains Restoration Trust, Pepperdine University

PI(s): R. Wayne, E. Curd, G. Bucciarelli


Approximately 60 years ago, the red swamp crayfish (Procambarus clarkii) was released or escaped (as freshwater bait or through pet abandonment) into aquatic habitat throughout the Los Angeles area. The crayfish has since become invasive and is responsible for disrupting ecosystems, wiping out local flora and fauna such as stream-breeding amphibians, and causing cascades of change that lower stream water quality.

We are working to assess and develop novel ways to manage red swamp crayfish, to improve stream habitat conditions for native species and ultimately preserve biodiversity. As a part of this process, crayfish are being continuously trapped to reduce population numbers. However, their densities are extremely high. As an example, over 80,000 crayfish were removed from a 2 km stretch of stream over a three-week period in June 2016. Live trapping is only effective for tracking adult populations because larvae are too small to be caught in traps. More sensitive detection approaches are critical for managing crayfish populations in streams.


We are planning to monitor crayfish populations through environmental DNA (eDNA) sampling, which is being used to detect the presence of shed crayfish DNA, and larvae, which do not get caught in traps. Simultaneously, we will also quantify how crayfish removal (i.e. restoration) improves the biological diversity of streams. There is evidence that an emergent pathogen could be used to control crayfish, and eDNA will being used to identify the potential biological control agent.


Mountains Restoration Trust, Pepperdine University, and Dr. Gary Bucciarelli are collecting water samples from pristine, invaded and recently restored streams in the Santa Monica Mountains (December 2016) and testing these samples for the presence of crayfish. Dr. Emily Curd will use a panel of metabarcoding primers to sequence the animal, microbial, and fungal communities in these streams.