Using Environmental DNA to Understand Biodiversity in a Marine National Monument

When I tell my friends that I'm going to collect environmental DNA samples in the Northeast Canyons and Seamounts Marine National Monument, their first question is always: Where is that?

Northeast Canyons and Seamounts Marine National is a highly protected area located about 130 miles east-southeast of Cape Cod, Massachusetts. It is similar in size to Connecticut. President Obama designated this area as the first marine national monument in the Atlantic Ocean in 2016.

NOAA shares management responsibilities with the U.S. Fish and Wildlife Service for activities and species within the monument. It is a relatively undisturbed environment, which could be called a true ocean wilderness. The chief scientist of this research expedition, Peter Auster, is a research professor emeritus at the University of Connecticut and a senior research scientist at Mystic Aquarium. When Peter asked me if I'd be interested in sailing together to collect environmental DNA samples from the monument, I answered with an enthusiastic yes.

An interdisciplinary research group mustered aboard R/V Connecticut. Peter Auster and others scuba dove to deploy baited remote underwater video cameras to study apex predators. Meta Miner and Mael Glon from U.S. Fish and Wildlife Service conducted seabird surveys. Mary Beth Decker of Yale University used a specialized net to collect and identify gelatinous animals.

And of course, I collected seawater samples for eDNA metabarcoding analysis to study biodiversity in the monument, including fish and marine mammals.

Besides the fascinating habitat we studied, this expedition offered unique research opportunities for me.

Pinpointing Fish Hotspots

First, I was able to sample eDNA adaptively. In past research cruises in the open ocean, I usually take samples from depths with interesting chemical or physical features such as a layer where water temperature changes drastically, called a thermocline. However, these depths don't necessarily correspond to fish hotspots. Peter and I used sonar during this trip to find the deep scattering layer, which is an indicator of biomass. We made sure to take water samples from that depth.

Testing a More Efficient Sampling Method

I tested the practicality of using an eDNA sampler on this trip instead of the more traditional vacuum filtration method which requires more steps to set up and operate. Research biologist Marjorie Lyssikatos and I have used the eDNA sampler in the Southern New England Wind Energy Area, but this was the first time I used it on an open ocean expedition. We filtered 104 liters of seawater within 3 hours on deck-a success!

Luckily, a deep-sea coral research expedition took water samples for eDNA in the monument 3 days before our trip. I will analyze those samples, which were collected using a different type of filter than I used with the eDNA sampler. If there are enough samples for me to meaningfully compare eDNA results between this trip and the deep-sea coral expedition, I can learn how filter membrane pore size affects eDNA results. This information will be useful for eDNA researchers to improve their methods.

Mentoring the Next Generation of Scientists

Last but not least, summer intern Abby Lucas, a M.S. student at Southern Connecticut State University, sailed with me on this expedition-eDNA is a growing research area attracting young talent. Abby uses eDNA in her thesis work and was eager to get some sea exposure. It was absolutely rewarding for me to teach Abby eDNA operations on a research vessel and see her enjoying all that a research cruise has to offer.

Our expedition was cut short because of weather conditions and a mechanical issue with the boat. Though I felt a bit disappointed, I remembered not to take things for granted. Ocean expeditions, especially one like this with an array of operations onboard, are complicated. They require budget, weather, personnel, and equipment working at the same time.

I am grateful to be part of this interdisciplinary exploration project. I can't wait to work out the eDNA results and compare them with results from my colleagues. I hope our expedition will contribute a lot to understanding this unique ecosystem.

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