Community Oceanography with low-cost, open-source CTDs

On September 14, 2022, I gave a talk on community oceanography and the OpenCTD for the AtlantOS Ocean Hour “Democratizing ocean observations through low-cost technologies” workshop. Below is the transcript from that talk.

Good morning and thank you for inviting me.

Access to the tools of science is not equitable, and nowhere is this inequality of access more pronounced than in the ocean sciences, where all but a few entities have the capital to mount major oceanographic research campaigns. I come from the world of deep-sea ecology, where budgets can quickly climb into the tens of millions of dollars. But even small-scale coastal research can be stymied by the need for vessels, equipment, and instruments, access to which is often controlled by research institutions.

As the need to understand the dramatic changes happening both at the surface and beneath the waves accelerates, barriers to access that precludes the participation of the full breadth of ocean stakeholders erodes our potential to understand, anticipate, and mitigate those changes.

One of the missions of my post-Academic career has been to make the tools of ocean science more accessible to more people. I believe that the ocean belongs to everyone and that the tools to study the ocean should be available to anyone with the curiosity and motivation to pursue that inquiry.

Chief among those tools is the workhorse of oceanography, the CTD.

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The next generation of low-cost, open-source oceanographic instruments is here! Meet the OpenCTD rev 2!

Four generations of OpenCTD. Left to Right: Prototype 2, which went through sea trials in Lake Superior, rev 1, rev 1 in the smaller form factor (this one was deployed in Alaska), and OpenCTD rev 2.

In 2013, Kersey Sturdivant and I embarked upon a quixotic quest to create an open-source CTD — the core tool of all oceanographic research that measures the baseline parameters of salinity, temperature, and depth. We weren’t engineers; neither of us had any formal training in electronics or sensing. And, full confession, we weren’t (and still aren’t) even oceanographers! What we were were post-doc marine ecologists working with tight budgets who saw a desperate need among our peers and colleagues for low-cost alternatives to insurmountably expensive equipment. And we had ties to the growing Maker and DIY electronics movements: Kersey through his work developing Wormcam and me through my involvement with OpenROV. 

We had no idea what we were getting ourselves into. 

The very first OpenCTD prototype.

Seven years and five iterations later, we are releasing the long anticipated OpenCTD rev 2 as well as the comprehensive Construction and Operation Manual! OpenCTD rev 2 builds on over half a decade of iteration and testing, consultation with oceanographers, engineers, developers, and makers around the world, extensive coastal and sea trials, and a series of workshops designed to test and validate the assembly process. 

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The next generation open-source, 3D-printable Niskin bottle has arrived!

The Niskin bottle, a seemingly simple device designed to take water samples at discrete depths, is one of the most important tools of oceanography. These precision instruments allow us to bring ocean water back to the surface to study its chemical composition, quality, and biologic constituency. If you want to know how much plastic is circulating in the deep sea, you need a Niskin bottle. If you need to measure chemical-rich plumes in minute detail, you need a Niskin bottle. If you want to use environmental DNA analyses to identify the organisms living in a region of the big blue sea, you need a Niskin bottle.

Niskin bottles are neither cheap nor particularly easy to use. A commercial rosette requires a winch to launch and recover, necessitating both a vessel and a crew to deploy. For informal, unaffiliated, or unfunded researchers, as well as citizen scientists or any researcher working on a tight budget, getting high-quality, discrete water samples is an ongoing challenge.

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Documentation is the beating heart of open-science hardware: Help make ours better!

Four generations of OpenCTD.

The OpenCTD and Oceanography for Everyone has been a five year journey from inception to first field-ready model and we’re just getting started. Building a community-driven project like this requires not just expertise (that we didn’t have when we started), passion, resources, it requires documentation. Extensive, detailed, thorough documentation. Documentation is what sets an open-science hardware project apart from just another lab hack. It allows other users to replicate and validate your design. It’s the key ingredient that makes a project like the OpenCTD actually Open.

As we’ve expanded the OpenCTD, we’ve maintained comprehensive instructions for construction and operation. We’ve included notes from critical field deployments, raw data for comparisons, hardware tests, and support software.

In a lot of ways, documentation is the peer-review of open-science hardware projects.

We need your help! We are in the midst of preparing our first hardware manuscript for the OpenCTD. This paper will be a benchmark for the project and provide a citable resource for CTD users. As part of the manuscript, we will archive a static version of the OpenCTD documentation in a permanent repository for reference. Here’s what we need from you:

Hey Team Ocean! Southern Fried Science and Oceanography for Everyone is supported by contributions from our readers. Head over to Patreon to help keep our servers running an fund new and novel ocean outreach projects. Even a dollar or two a month will go a long way towards keeping our website online and producing the high-quality marine science and conservation content you love.

Ocean Outreach in an Evolving Online Ecosystem: Exploration wants to be shared

This is the transcript of the keynote I delivered at the Fourth International Marine Conservation Congress in St. John’s, Newfoundland. It has been lightly modified for flow.

Read Act II: Transforming the Narrative.


Now I want to shift gears and look towards the future, where we’re going, and what tools are available to help us get there. Because the future of ocean outreach, and really the future of ocean conservation, comes down to this one concept: “Exploration wants to be shared”.


Sealand courtesy the Daily Beast

The online ocean ecosystem is full of platforms–preexisting tools that allow us to produce, share, broadcast, enhance, and manage our outreach campaigns. Not just the obvious ones like Twitter and Facebook, but more niche tools like Slack, github, Ushahidi, medium, and yes, even PokemonGo, or if you want something a bit more serious, consider R as something that’s not just a statistics package, but a way to share your own software and data with the scientific community.

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Fun Science FRIEDay – Open-Acess Science for the Masses

The oceans belong to all of us. With this simple statement in mind, the Oceanography for Everyone (OfE) project was launched with the goal of making ocean science more accessible. One of the biggest hurdles in conducting ocean science is instrumentation costs, and 4 years ago the OfE team began trying to make one of the most basic ocean science tools, the CTD (a water quality sensor that measures Conductivity-Temperature-Depth), cheaper… much, much cheaper!

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Open source. Open science. Open Ocean. Oceanography for Everyone and the OpenCTD

Andrew compares the OpenCTD readout to a hand refractometer, because apparently he's a hipster ecologist.

Andrew compares the OpenCTD readout to a hand refractometer, because apparently he’s a hipster ecologist.

Nearly four years ago, Kersey Sturdivant and I launched a bold, ambitious, and, frankly, naive crowdfunding initiative to build the first low-cost, open-source CTD, a core scientific instrument that measures salinity, temperature, and depth in a water column. It was a dream born from the frustration of declining science funding, the expense of scientific equipment, and the promise of the Maker movement. After thousands of hours spent learning the skills necessary to build these devices, hundreds of conversations with experts, collaborators, and potential users around the world, dozens of iterations (some transformed into full prototypes, others that exist solely as software), and one research cruise on Lake Superior to test the housing and depth and temperature probes, the OpenCTD has arrived.

Kersey strike a pose while deploying an OpenCTD in our local estuary.

Kersey strikes a pose while deploying an OpenCTD in our local estuary.

Over the last week, Kersey and I have been hard at work building a battery of CTDs while methodically documenting the construction process. You can watch the event unfurl on the #HackTheOcean hashtag. We now have three new CTDs ready to be distributed to collaborators at various institutions for more field tests and, in particular, to assess the precision of three different conductivity probes, all of which have been calibrated and validated here, in Virginia.

OpenCTD versus commercial CTD temperature and depth test. Conductivity test are occurring this summer, but initial surveys indicated no significant deviation from commercial instruments (indeed, we’re even using a commercial conductivity circuit that has been thoroughly tested in other environmental monitoring contexts.)

Now, finally, after 4 years of challenges and opportunities, of redesigns, re-education, and re-development, it’s time for you to join our open-source community of Citizen Oceanographers and build your own OpenCTD!

We’ve hosted the entire build guide, as well as the software, 3D printer files, support documentation, and raw data from our first research cruise in the Oceanography for Everyone GitHub repository, where you can also find guides and designs for the BeagleBox field computer and the Niskin3D 3D-printable Niskin bottle. 3D print files are also available on Thingiverse, if you’re more comfortable with that platform. We’ve also gone out of our way to make the build as simple as possible. You’ll need to learn basic programming and electronics, but the technical aspects of building your own CTD shouldn’t be a barrier to entry.

Over these four years, the OpenCTD has grown from a single project to a community of citizen oceanographers committed to making the tools needed to study the oceans as accessible as possible. As my friend and colleague Eric Stackpole said upon launching the first OpenROV kickstarter:

“Ocean exploration shouldn’t require a research grant, it should require curiosity.”

Since launching, numerous people have asked us if we can build an OpenCTD for them. We are not really set up to be a manufacturer of CTDs, however, get in touch with either me ([email protected]) or Kersey ([email protected]) and we can talk about holding an OpenCTD training workshop with your institution or organization.

Dive the Wreck of the Steamship Tahoe with OpenROV!

OpenROVOne-hundred-fifty meters hardly seems like anything at all.

Standing in the parking lot of OpenROV, I pace out 150 meters. The small sign, hanging against the wall of the battered warehouse, pointing visitors towards the entrance, is clear.

One-hundred fifty meters is less than half a lap around a standard running track. It’s the height of Old St. Paul’s Cathedral, the tallest building in the world, 700 years ago. The fastest man in the world could cover 150 meters in 14 seconds.

On land, 150 meters is barely noteworthy. Plunge into the sea and 150 meters is the wine dark deep. It is the edge of the photic zone, a world of eternal twilight. It is three times deeper than most SCUBA divers will ever venture. At 150 meters, the water pushes down with the weight of 16 atmospheres.

And, if you climb high into the Sierra Mountains and descend into the frigid alpine waters of Lake Tahoe, just off the coast of Glenbrook, Nevada, lying on a steep glacial slope at 150 meters depth is the wreck of the Steamship Tahoe.

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Oceanography for Everyone: Empowering researchers, educators, and citizen scientists through open-source hardware

Three years ago, Kersey Sturdivant and myself launched an ambitious crowdfunding project–the OpenCTD–with the plan to produce a low-cost, open-source CTD for thousands of dollars less than the commercial alternative. That campaign fizzled, bringing in barely 60% of our target goal. After taxes and fees, that amounted to about $3500 available to us to play around with. The OpenCTD wasn’t dead, but it was on life support.

We had a vision: to make to tools of oceanography accessible to the widest range of people, not just ocean researchers, but citizen scientists, boat-owners, fishermen, surfers, swimmers, any one who enjoyed the ocean and wanted to better understand their local waterways. The OpenCTD was ambitious, not only in its scope, but also in our ignorance of the knowledge required to achieve that goal. In the three years since, I moved to California (and then moved back East) to meet with some of the best underwater engineers in the open-source movement. We added Russell Neches, an experienced hardware hacker to our team. We partnered with OpenROV to learn from their vast experience. And I’ve spent the time re-skilling: learning to code, design and fabricate 3D printable materials, build electronic components from the ground up, and manage an open-source project.

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