The importance of eDNA

Meilina Dalit

Today we repeated yesterday’s activities of coordinating simultaneous sampling from the R/V Western Flyer (CTD casts), the Reuben Lasker (midwater trawls), and LRAUV Aku (Environmental Sample Processor sampling).

While LRAUV Aku is autonomously collecting samples with a third-generation Environmental Sample Processor (ESP), Research Specialist Kevan Yamahara is also archiving water samples from the CTD rosette using a benchtop ESP on the Western Flyer.

Similar to the way forensic scientists can find genetic clues from suspects at a crime scene, researchers can analyze seawater samples to obtain environmental DNA (eDNA)—DNA that originated from a wide variety of animals—to assess the distribution and relative abundance of animals in a particular location and time. Kevan will compare the eDNA data from the benchtop ESP and LRAUV Aku’s ESP.

Chief Scientist Francisco Chavez was recently awarded a grant through the National Ocean Partnership Program to test the usefulness of eDNA as part of the Marine Biodiversity Observation Network (MBON) program.

MBARI researchers Kris Walz, Julio Harvey, and Katie Pitz are also archiving the same water samples as Kevan using a peristaltic pump system, to determine how different sampling methods affect the types and amounts of genetic material detected in each sample.

A final comparison will come when marine biologists visually examine net samples that were collected aboard the NOAA research vessel Reuben Lasker at the same time as samples were being collected by the Aku ESP and the shipboard ESP. The abundance and taxonomic composition of animals caught in the nets will then be compared with the genetic taxonomies compiled using eDNA.

This evening Francisco led a post-dinner science meeting in which he reviewed the overall research goals of the cruise and the sampling activities for the evening.

With heavy winds predicted throughout the weekend, the Western Flyer will head back to Moss Landing on Friday morning, and our cruise will be suspended until Sunday evening. But while the Western Flyer sits in port, the AUVs, gliders, and wave gliders involved in this project will continue collecting data despite the bad weather. This illustrates the benefits of autonomous platforms and how they allow us to maintain a research presence in the bay when conditions make it uncomfortable or unsafe for humans to be out at sea.