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Underwater remote sensing: Surveying the marine world safer, faster, and more affordably

January 23, 2020

Futuristic-sounding sensors let scientists work in multiple places at once, but it’s important to begin with a clear study design

Underwater remote sensing is fascinating. This technology allows us to observe and measure key elements of underwater ecosystems using a variety of remote sensors and underwater platforms. Previously, we had to venture out to sea during all times of year we wanted to monitor these ecosystems. While we still go out on ships to deploy most sensors—and for many other reasons—modern underwater remote sensing technology often provides better, safer, and less costly options to get the job done.

While it’s a great advantage to have these new underwater remote sensing tools at our disposal, the challenge now is using the right piece of technology. The task of clearly articulating your questions and objectives still falls to the scientist with knowledge of the system dynamics and variability; only then can you select the proper remote sensing tool.

A well established and reliable underwater remote sensing measurement tool is oceanographic moorings. (Photo: Bob Pickart)

Who can benefit from underwater remote sensing?

What sorts of projects might require or benefit from this technology? If your project—new or ongoing—has the potential to affect the marine environment in some way, then you would likely benefit from information that underwater remote sensing can deliver.

Perhaps you’re installing a new port, energy terminal, harbor, or desalination plant. Maybe you’re expanding a marina. Perhaps you’re putting in a pipeline, transmission cable, or fiber-optic cable along the ocean floor.

All these activities can impact the marine environment in different ways—from plankton, fish, birds, and marine mammals, to water and sediment quality. In most instances, baseline data for key parameters like sediments, water quality, habitats, fish, and marine mammals are needed.  

You’ll likely use this data for an environmental assessment or an environmental impact statement. Then, during construction and after you’ve installed or updated your project, you must monitor any impacts of your activity. This monitoring often extends across the entire life cycle of a project. So, it can be costly and involve complicated logistics.

Use of underwater remote sensors on wildlife helps scientists better understand migratory paths and habitat use. (Photo: Rowenna Gryba)

The traditional approach

Before underwater remote sensing, we collected this data manually, often while onboard a boat or ship. As much as I enjoy being out at sea, the sun on my face, the wind in my hair, smelling the salty breeze, this traditional approach also comes with downsides. Compared with underwater remote sensing, being out at sea for extended periods is time-consuming and costly. It is also more restrictive in terms of space because you can only be in so many places at once.

Some of the more traditional measuring techniques involve sending different types of equipment, such as water samplers and temperature and salinity sensors hooked onto wires, into the ocean depths. Traditional monitoring also may utilize nets to sample for plankton and fish, or using underwater acoustics, perhaps mounted to the hull of the ship. There is great tradition and consistency in sampling the ocean this way, and these data have solved many ocean mysteries. But these approaches are inherently limited to the locations that a vessel can safely and practically reach. That means a lot of the ocean space, at many times of the year, has not been accessible to us in the past.

It’s important to also note that underwater remote sensing provides a safer option, since your team doesn’t need to face the prolonged risks that inherently come with being at sea.  

Various sensors (physical, biological, chemical) can be placed on gliders. Through satellite telemetry they feed data from any body of water in the world to any remote location. (Photo: Donglai Gong)

The underwater remote sensing approach

There are many types of remote sensors that help us measure different types of information. Some sensors relay information to us in real-time, via satellite, others record the information and we need to go back to pick up the hardware out of the ocean. Some, like moorings, are anchored, providing detailed information from one location over long periods of time. Others, such as drifters, sail drones, or underwater autonomous vehicles, are mobile and focus on measuring the same information at many locations. Some robotic sensors resemble little remote-control submarines. Others we put on animals—such as seabirds, seals, and whales—and the animals then sample the ocean for us as they go about their normal business. For some of these sensors, like underwater gliders that look like torpedoes and swim through the ocean collecting data, I can sit in my office and control them no matter where they are in the world.

These different sensing platforms can be equipped with similar type of sensors and used to measure currents, temperature, depth, ocean chemistry, plankton, fish, and even marine mammals. Some are even equipped with video that provide rare glimpses into the underwater world. Most of this remote technology does not collect samples but, rather, measures ocean characteristics.

One of the more common tools employed is acoustics. We use acoustics both in the classic sense of listening to animals, like whales and seals, making sounds that help us identify species, while also determining what and how many other organisms, like plankton and fish, are within reach of the sensors.

I can sit in my office and control sensors around the world.

Define your objectives to determine the right tools

Since there are so many underwater remote sensing options available, both in terms of platforms and sensors, it is key to define your objectives and create a proper study design before implementing this technology. Articulate your question clearly, because otherwise you might be using the wrong tool to collect your data—like trying to use a hammer to remove a screw.

Just because you can put a robot four miles underwater to collect data doesn’t mean that you should—or that the robot will acquire the data you need. You will no doubt measure something, but will it really answer your question? You could waste your money, or worse, face legal issues in the future because you didn’t accurately establish baseline conditions.

Old meets new

I’m thrilled to have the chance to use these fascinating underwater remote sensing tools. Technology has made marine data collection safer, quicker, more affordable, and allows us to measure things we could not before, in places or at times we could not reach. But cool tech still needs good old-fashioned science to get the job done properly. You can’t have one without the other. Define your objectives and clarify questions before you go looking for the best tools for your project.

It’s important to work with a team that can shape your study design, find the right data, establish a baseline, and know how to monitor your project effectively. Contact me if you’d like to learn more about this intriguing approach to marine data collection.

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