National Marine Fisheries Service
11/23/2021 | News release | Distributed by Public on 11/23/2021 13:14
Fear of the Unknown, and How the Unknown Becomes Known. You Know?
I've written before about my fear of technology. I've never been one of those people who rushes out to buy the latest and greatest new gadget. Once I eventually learn to use a gadget - a cell phone, for example - I stick with it and stay in my technology comfort zone.
Image
A glider with a shadowgraph camera mounted to the nose. Credit: NOAA Fisheries/Jen Walsh
Over the last three years, I have cultivated a squishy glider comfort zone. I'm not entirely comfortable with gliders, but the paralyzing fear I felt when I first started working with them has subsided as I've become more familiar with all of their sensors and how they work.
This is why getting new sensors added to gliders is somewhat terrifying for me.
Let me back up.
The most important data we collect with gliders is acoustic data for estimating krill biomass. I describe this in detail in an earlier post, but to summarize: the gliders have a sensor that uses sound to identify and quantify krill. For years, scientists have used sound to estimate the biomass of animals that swarm in the open ocean where we can't see them. But then we thought, what if we could actually see for ourselves what the gliders use sound to see? What if we could even see animals so small the gliders can't detect them with sound?
Well, now we can. We've added cameras to the gliders.
We have two different types of glider cameras: regular ones that take normal pictures, and ones called shadowgraph cameras, which take pictures of shadows. The regular cameras - equipped with red flashing lights for illuminating the water without scaring animals away - are inside the gliders, with just the lens visible on top. The shadowgraph cameras are mounted to the nose of the gliders and make the gliders look like double-horned unicorns. The "horns" are about 12 inches apart, and each horn has a lens that faces the other lens. Behind one lens is a light source, and behind the other lens is an image detector. Any small zooplankton that swim between the horns - krill or even smaller zooplankton, like copepods - will have their "shadows" captured by the shadowgraph.
Why two camera systems?
We will use the images captured by the regular cameras to confirm what the gliders see using sound. Because sound bounces off of objects in characteristic ways, we are confident that our acoustic sensors are "seeing" krill, but we can validate our data when we can see the krill for ourselves in photographs.
The shadowgraph images are trickier to explain. Why in the world is taking a picture of an animal's shadow useful? It turns out that images of shadows - especially shadows of tiny animals, like krill larvae, that our acoustic sensors can't detect - are much sharper than images taken by a regular camera. While we won't be able to estimate the biomass of these tiny animals, we can use shadowgraph images to identify them and learn more about them. We can study their preferred habitat, where they hang out in the water column, and how their populations may change in both space and time as the Southern Ocean gets warmer.
Deep down, I know putting cameras on gliders is super cool. I can't wait to see the images we get. Superficially, I'm nervous. We have to learn a lot about how to program these cameras to take the best images possible. At least once the gliders and cameras are deployed, there's one rookie mistake I won't be able to make. I can't accidentally put my finger over the lens.
Three images showing the shadowgraph process (l-r): A small action figure; the small action figure in between the shadowgraph lenses; and shadowgraph image of the action figure. Credit: NOAA Fisheries/Jen Walsh.