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Appendix A: New Technology Deployments

Three new technologies developed by the MIT Future Ocean Lab & MIT Media Lab were deployed aboard Lindblad Expeditions in 2019.

Published onSep 18, 2021
Appendix A: New Technology Deployments
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MicroCTD

Junsu Jang
Deployed in SE Alaska aboard National Geographic Venture, 23-29 June 2019

We are working on a new low-cost, high-precision and space-efficient conductivity, temperature, depth (CTD) sensor that would be mass-deployable. These sensors together can tell us about the physical properties such as salinity and density of the seawater. The goal of this project is to enable ubiquitous deployment of CTD on everything that touches the water, ranging from boats to floats to docks to scuba diving gears. We are aiming for roughly 3 decimal places of accuracy, which is sufficient for scientific value in the vast majority of ocean situations. 

Deployment

Four CTDs were brought to Alaska so that the system and relevant measurements could be taken. Another goal of this trip was to learn about what is required to mass-deploy modular sensors. When Deep Sea Camera Systems were deployed, available CTDs were strapped onto its side using multiple zip-ties. There were five deployments in total, and there was one time that I tried to deploy from a kayak. We discovered multiple failure modes and problems with our sensors.

Results

  • Out of the four CTDs, two leaked water through the epoxy bonding the acrylic endcap and the Delrin cylinder. Air pockets formed on the potted sensor electronics. 

  • Re-assembling housing every time to retrieve data and update the software is quite cumbersome. It was manageable with four, but it will certainly not be the case if you had more than ten of them. This calls for either wireless unit such as RPI Zero or ESP8266.

  • The temperature required a very long time (~5min) to reach the temperature of the water. We need to better design the heatsink. 

  • Conductivity sensor was premature for deployment that we could not analyze its accuracy and precision from this trip.

    a. CTD strapped onto the Deep Sea Camera System. Multiple failure modes for the housing occurred. b. The endcap broke in the middle of assembly. c. Water sipped through the epoxy between the Delrin cylinder and acrylic endcap. d. Delamination, as seen by the air pockets, occurred on one of the potted electronics.

Environmental DNA (eDNA) Sampler

Charlene Xia & Jacob Bernstein
Deployed in Channel Islands, California, aboard National Geographic Venture, 7-11 December 2019

We are developing a low-cost compact underwater eDNA sampler. Environmental DNA or eDNA is DNA that is collected from a variety of environments rather than directly sampled from an individual organism. The analysis of eDNA has great potential, not only for monitoring common species, but to genetically detect and identify other extant species that could influence conservation efforts. The eDNA project is a joint effort between MIT Future Ocean Lab, Woods Hole Oceanographic Institution Dana Yoerger's group and Annette Govndarajan's group. 

December 8 - Testing the Water

 After an introduction to the amazing crew and a short exploration of the ship, we set up and assembled the eDNA sampler and the radiometer. For the first deployment, our main goal is to run through the deployment process and test the eDNA sampler and radiometer housing. Both devices were deployed to about 50m. James Hyde, a naturalist on board, volunteered to take us out on the Zodiac. With his expertise in ship knots, he helped us to secure and deploy the eDNA sampler and radiometer. Both test deployments went smoothly without surprises. 

December 9 - Double the Sampler

The mission for day two was a full deployment and testing of two eDNA samplers. Two eDNA samplers have two slightly different sets of hardware. We aimed to test the performance of both eDNA samplers. James took us out on the Zodiac, helped and taught us how to make the proper knot to secure and deploy the two eDNA samplers. Both samplers were in the water for 10 minutes, maximum depth research is around 15m. 

December 10 - All Together Now

The weather at Catalina Island was great, the water was calm, barely any wind. The deployment goal was to do a full deployment test with the radiometer and one eDNA sampler. The deployment ran for 30 minutes, reached a maximum depth of 60 m. The eDNA sampler was set to start sampling between the depth of 50-70 m. The eDNA sampler successfully collected the depth reading when it reached below 2 m. The depth reading also was a useful correlation point for the radiometer. 

Overall, this expedition has been a successful preliminary test deployment with both the eDNA sampler and the radiometer. We gained a lot of valuable experiences of deployment, device rigging, and field testing from this expedition. We now also have a clear path to the next iteration for both devices. Thank you, Lindblad-National Geographic Expeditions, for this amazing field test opportunity! 

Radiometer

Jacob Bernstein & Charlene Xia
Deployed in Channel Islands, California, aboard National Geographic Venture, 7-11 December 2019

In December 2019, sailing with Lindblad Expeditions on the National Geographic Venture around California’s Channel Islands, we performed the first zodiac-based deployments of a radiometer developed by the Future Ocean Lab at MIT. This radiometer is designed to measure light throughout the ocean’s mesopelagic twilight zone, a region extending from depths of 200 to 1,000 meters, home to the largest daily migration of life on the planet. Measurement of ambient light levels, which decrease 100 million fold from the top of the twilight zone to the bottom, are necessary to test the hypothesis that many species move to maintain their position within a narrow light comfort zone (e.g. to track food sources or avoid predation). Other light signals of interest, such as spectral features that indicate the presence and activity of specific species of fish (e.g. counter-illumination that provides active camouflage from predators), and bioluminescent signaling events lasting a fraction of a millisecond, will provide a window for rich observations of an ecosystem of increasing interest for marine biologists, climate scientists, and the fishing industry. 

Our radiometer, deployed once previously as part of a large ROV sensor package, featured for this deployment new sensor interface electronics to increase the sensitivity range and reliability of light measurements, and new electronics, energy storage, and software to enable autonomous data collection. Autonomous deployment from a zodiac necessitated a new method of rigging the radiometer to a casting line, which we developed with the help of James Hyde, our collaborator on-ship, who was instrumental in all stages of our successful deployment. On our first full day aboard the Venture, we tested the rigging strategy on an empty pressure housing with a short cast to 20 meters. Deploying from a ship of opportunity such as this one also required us to develop new procedures for on-ship electronics testing, mechanical assembly, and modification, using only the toolkit with which we traveled (and a Dremel helpfully provided by the crew); this work consumed our second day on ship. On our final day, we deployed the operational radiometer about a mile offshore from Catalina Island to a depth of 50 meters for half an hour at dusk, recovering the instrument and all of its data without incident. We are still in the process of analyzing the data, and are optimistic that the position and time of the measurements will provide a good range of light levels for evaluating the radiometer’s performance.

The importance of readying the radiometer for deployments from ships of opportunity, with data and energy storage for autonomous data collection, must be emphasized. Not only does an ROV provide a source of interference for sensitive light measurements - both from on-board lights, and propulsion systems that mechanically induce bioluminescence from nearby plankton - but large ROV deployments are expensive, and relatively rare. The light of the twilight zone varies with location, season, moon phase, and water clarity, and so to properly map this region, our radiometer must be deployed more often and in more places than ROVs can venture. The LEX cruise, with the gracious help of all her staff and crew, was an ideal environment for the first autonomous deployment of our radiometer.

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