Community oceanography using low-cost, open-source CTDs

Community oceanography using low-cost, open-source CTDs

On September 14, 2022, I delivered a lecture on Community Oceanography and OpenCTD at the AtlantOS Ocean Hour Workshop “Democratizing Ocean Observations through Low-Cost Technologies”. Below is a transcript of this hadith.

Good morning and thanks for inviting me.

Access to the tools of science is unfair, and nowhere is this disparity in access more evident than in ocean science, where all but a few entities have the capital to undertake major oceanographic research expeditions. I come from the realm of the deep sea environment, where budgets can quickly climb into the tens of millions of dollars. But even small coastal research can be hampered by the need for ships, equipment, and tools that research institutions often control access to.

With the acceleration of the need to understand the dramatic changes occurring on and below the surface of waves, barriers to access that prevent the participation of the full range of ocean stakeholders are eroding our ability to understand, anticipate and mitigate these changes.

One of the tasks of my career after the academy was to make oceanographic tools accessible to more people. I believe that the ocean belongs to everyone and that the tools for studying the ocean should be available to anyone who is curious and motivated to pursue this research.

Among these tools is the backbone of oceanography, the CTD.

Just in case no one knows, a CTD is a device that measures salinity, temperature, and depth. It can be used to characterize a water column, attach it to other instruments to correlate observations with water conditions, or deploy it as a fixed anchor for long-range observation. Almost all marine scientific research includes the CTD group.

But commercial CTDs are expensive. This creates a barrier to access for many of the people most imminently affected by the changing of our oceans.

OpenCTD is a low-cost, open-source alternative to commercial CTD devices purposely designed for budget-conscious scientists, educators, and practitioners working in near-shore coastal ecosystems, where full-fledged research projects can be conducted for less than the cost of commercial CTDs. Sensor quality is acceptable for the vast majority of environment and conservation studies – although you probably wouldn’t want to use one for chemical or physical oceanography – and operates at a depth of 140 metres.

OpenCTD can be built for about $350 in parts and another $200 in tools and consumables.

I started developing OpenCTD during my journey through docalypse, looking for inexpensive ways to continue doing my marine research while navigating short term academic appointments. Since I’m not an engineer, the early years of OpenCTD development were a steep learning curve as I engaged with members of the budding maker community to create increasingly more sophisticated hardware. In the eight years since the project began, the OpenCTD family has grown from a core team of marine ecologists to a distributed community of scientists, engineers, makers and conservation practitioners worldwide.

Throughout the entire development cycle, the primary task has always been to produce a tool that any user can build and understand. We didn’t want to create another data black box, we wanted to create something that would be completely at home in a high school classroom as a top-tier research institution.

The brain of OpenCTD is an Arduino microcontroller, a commonly available children’s computer that can control an array of sensors using a relatively accessible markup language. Arduinos are used in classrooms around the world as an introduction to coding and hardware development. The Arduino talks to a real-time clock, which timestamps all the data, as well as an SD card reader where all the data is logged. All of these components, when combined with a commercial salinity interpretation chip and a 3.7V lithium polymer battery, make up the control unit.

The controller then interacts with a sensor package that includes a battery of three temperature sensors, an absolute pressure sensor that provides depth, and a graphite probe that measures conductivity, which then translates into salinity. Everything inside a PVC pipe is very boring. The sensors are fully mounted in epoxy and the open end is covered with a pressure-ready cap that plumbers use to test pipes but we’ve found that they keep air down up to 140ft for a fraction of the cost of an engineering solution.

Using a custom circuit board that we designed and released under an open source license, anyone with no prior electronics, soldering, coding or manufacturing experience can build, calibrate, and deploy OpenCTD over a long weekend.

This design process highlights the core principles of OpenCTD. We want our hardware to be as inexpensive as possible while still producing high quality data. We want everything we can to be released under an open source license, so that anyone can use the basic OpenCTD, extend it, iterate it, and adapt it to their needs. And we want the materials we use to be as affordable as possible, so that people who want to build a CTD can find the parts they need at their local hardware stores, and from major online retailers.

We have also adopted a values-neutral approach to implementation. By neutral values, I mean that I do not believe that technology, in and of itself, is a panacea, but rather that carefully designed conservation technology programs can help bridge the gap between detecting emerging problems and the will to solve them at the policy level. I focus on preservation technology that enhances ownership of both data and tools for data collection within communities in a stakeholder implementation model. This means that rather than taking a top-down approach to providing technological solutions to the problems facing our oceans, I would rather work with communities to develop solutions that reflect and respect their own needs and values. This often means that my goals are not aligned with the dominant model of Imported Magic, where technology developers want to provide one-size-fits-all solutions to local and regional problems.

Imported Magic, by the way, is the technological brother of parachute science.

So anyone can build their own CTD, but the main way we’ve kept this program funded is by hosting training workshops to teach students at many levels how to build their own tools. Over the past few years, I’ve hosted local CTD building workshops for me in Maryland, with marine educators at Stellwagen Bank National Marine Sanctuary, and remotely, with middle and high school students in Homer, Alaska.

For students, the OpenCTD creation process provides an introduction to coding, 3D printing, hardware prototyping, and electronics and can provide a practical foundation for courses in Earth sciences, marine or environmental sciences.

I want to introduce you to another project that is currently in progress. This year we sent OpenCTDs to naturalists working on commercial whale-watching boats across New England to record and upload data to an opportunistic pilot while searching for whales. You can track their progress and check their data in the oceans.com community.

There are so many people to thank in such a short time. OpenCTD is a community effort and always will be, but I want to acknowledge our lead funders whose support has kept the project alive long enough until we get to this point. And if you want to check out the entire OpenCTD project, I recommend you to start with our GitHub repository, where we provide all documentation and source files. From there you can find the complete OpenCTD build and run guide, which explains the OpenCTD build process in detail.

Thank you.


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#Community #oceanography #lowcost #opensource #CTDs

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