Saving Seafood

Underwater robot offers new insight into mid-ocean “twilight zone”

June 17, 2021 — The following was released by the Woods Hole Oceanographic Institution:

An innovative underwater robot known as Mesobot is providing researchers with deeper insight into the vast mid-ocean region known as the “twilight zone.” Capable of tracking and recording high-resolution images of slow-moving and fragile zooplankton, gelatinous animals, and particles, Mesobot greatly expands scientists’ ability to observe creatures in their mesopelagic habitat with minimal disturbance. This advance in engineering will enable greater understanding of the role these creatures play in transporting carbon dioxide from the atmosphere to the deep sea, as well as how commercial exploitation of twilight zone fisheries might affect the marine ecosystem.

In a paper published June 16 in Science Robotics, Woods Hole Oceanographic Institution (WHOI) senior scientist Dana Yoerger presents Mesobot as a versatile vehicle for achieving a number of science objectives in the twilight zone.

“Mesobot was conceived to complement and fill important gaps not served by existing technologies and platforms,” said Yoerger. “We expect that Mesobot will emerge as a vital tool for observing midwater organisms for extended periods, as well as rapidly identifying species observed from vessel biosonars. Because Mesobot can survey, track, and record compelling imagery, we hope to reveal previously unknown behaviors, species interactions, morphological structures, and the use of bioluminescence.”

Co-authored by research scientists and engineers from WHOI, MBARI (Monterey Bay Aquarium Research Institute), and Stanford University, the paper outlines the robot’s success in autonomously tracking two gelatinous marine creatures during a 2019 research cruise in Monterey Bay. High-definition video revealed a “dinner plate” jellyfish “ramming” a siphonophore, which narrowly escaped the jelly’s venomous tentacles. Mesobot also recorded a 30-minute video of a giant larvacean, which appears to be nearly motionless but is actually riding internal waves that rise and fall 6 meters (20 feet). These observations represent the first time that a self-guided robot has tracked these small, clear creatures as they move through the water column like a “parcel of water,” said Yoerger.

“Mesobot has the potential to change how we observe animals moving through space and time in a way that we’ve never been able to do before,” said Kakani Katija, MBARI principal engineer. “As we continue to develop and improve on the vehicle, we hope to observe many other mysterious and captivating animals in the midwaters of the ocean, including the construction and disposal of carbon-rich giant larvacean ‘snot palaces.’”

Read the full release here

‘Environmental DNA’ Lets Scientists Probe Underwater Life

February 24, 2020 — Tracking down marine life isn’t easy. Ocean scientists drag nets through the water to find the fish or plankton they are looking for, tag whales with harpoon-like devices, or scuba dive with an erase-proof whiteboard and hand counter to tally reef fish. That’s how you count creatures underwater. But an emerging technology called environmental DNA, or eDNA, is easing this time-consuming and expensive process for scientists by allowing them to grab water samples and check for DNA.

Each drop of seawater contains thousands of microorganisms, as well as bits of skin, mucus, and waste shed by passing fish and mammals. Using a robotic laboratory mounted on an underwater drone that filters and sequences the DNA that it finds, scientists and engineers can now identify marine life without coming back to shore. “You don’t need a big ship to collect your samples,” says Chris Scholin, executive director of the Monterey Bay Aquarium Research Institute, which is developing this new technology along with several other research groups across the US. “This has become portable and small enough to operate in real time on an autonomous underwater vehicle.”

Sampling remotely means that scientists might not have to go to sea in stormy weather to collect data, and can allow them to sample over a long period of time, instead of collecting information during a three- or four-week cruise. It also doesn’t require them to harvest the fish. Robotic vehicles recently traced the DNA of great white sharks congregating in the middle of the Pacific Ocean, tracked tropical fish along the Jersey Shore as they headed north to escape climate change, and found farm-raised fish genes while screening samples from New York Harbor.

This new technology is driven by the marriage of a device the size of a thumb drive called an Oxford Nanopore Minion sequencer to another recent invention, ocean-going autonomous vehicles (AUVs) that no longer take commands from ship or shore. These devices can follow environmental signals, such as temperature, salinity or the optical properties of plankton, just like a hound sniffing out an escaped convict’s trail. (Researchers use sonar to find plankton, the way an angler would use a fish finder.)

Read the full story at Wired

Message in a bottle: Forensics meets marine science with eDNA

August 16, 2019 — It doesn’t look like much. At a glance, it seems Mark Stoeckle is holding a bottle of water to quench his thirst. But there’s so much more than H2O in that small plastic bottle.

Dr. Stoeckle pours the fluid through a special filter atop a glass contraption that looks a bit like a pour-over coffee maker. A yellowish gunk collects on the filter. Clearly this liquid isn’t potable. It’s seawater the scientist collected in Barnegat Light, New Jersey.

And that slime? That’s actually the stuff he wants. It potentially contains cells, or bits of cells, from as many as 20 species of fish that sloughed off into the water as the fish were going about their business. By sequencing the DNA fragments in that gunk, Dr. Stoeckle aims to identify which fish were swimming around the area just before he collected those water samples.

Read the full story at The Christian Science Monitor