The Story of Pedro and eDNA

Hello, deep-sea enthusiasts! It is Pedro A. Peres again with one more post on the blog. Today, I will talk more about metabarcoding environmental DNA (a long and fancy name for eDNA) being used to answer questions about the deep sea.

First thing, why is everybody talking about eDNA? This technique has gained popularity as a noninvasive method to inform conservation and management practices. By analyzing DNA shed by individuals in the environment, eDNA can characterize ecological communities of marine habitats that are not easily accessible and detect specific species and their spatial distribution without collecting specimens. In other words, eDNA does not require direct interaction with the organisms to obtain samples, minimizes disturbing animals and their habitat, and is particularly useful for monitoring protected species/areas for which obtaining sample permits can be restricted, time-consuming, or costly. Sounds amazing, right? But it is not as easy as it sounds. One of the significant challenges in using eDNA in the deep sea is collecting the environmental samples – water from the deep!

In this first NOAA Deep-sea Benefits (DSB) expedition, I am testing different eDNA samplers for current and future deep-sea investigations. One is very convenient, as it can be used with Niskin bottles coupled with a CTD, standard gears found in research vessels. After deployment, Niskin bottles can be triggered at a specific depth and location to collect water samples. After collection, water samples are filtered, and the filters are preserved for future processing. Looking at the photo, you might think: Ghostbusters? Dora the Explorer? Actually, just a scientist with a backpack eDNA sampler (https://store.smith-root.com/collections/edna-water-samplers/products/edna-sampler-backpack-lith-combo)

Photo:  eDNA backpack (aka Edna) to filter water samples

After bringing the CTD back on board, I’m connecting the backpack to the Niskin bottles to filter the water collected. We will use these samples to characterize deep-sea communities from different locations and understand their dynamics during day-night cycles. I’m thrilled to return to the lab and start working on these samples to unveil some deep-sea mysteries. Most of the fun is about to come. But while on board, although not seeing the animals, filtering water can has given me some excellent views!

Photo:  Pedro and Edna enjoying the sunrise!