Bioluminescence and Vision on the Deep Seafloor 2015

Beautiful Life

By Sönke Johnsen, Ph.D - Professor of Biology, Duke University
July 23, 2015

he deep-sea pandalid shrimp Heterocarpus ensifer and a photo of the same animal ‘vomiting’ light from glands located near its mouth.

The deep-sea pandalid shrimp Heterocarpus ensifer and a photo of the same animal ‘vomiting’ light from glands located near its mouth. Image courtesy of Sönke Johnsen and Katie Thomas. Download larger version (jpg, 72 KB).

Some things in life are easy, like scarfing down a bag of chips. Some things start out hard and then become second nature, like driving a car. But some things are genuinely hard, all the time. Hitting a fastball, parenting a child, and – as it turns out – driving a submarine.

Figure 1: Jamie (right) and Tony (left) at the controls of the ROV Global Explorer. In Jamie’s left hand is the joystick that he uses to pilot the vehicle. The various monitors in front of them tell them what the ROV sees and where it is. Tony is monitoring the SONAR (lower middle monitor) to find a deep-sea camera system.

Figure 1: Jamie (right) and Tony (left) at the controls of the ROV Global Explorer. In Jamie’s left hand is the joystick that he uses to pilot the vehicle. The various monitors in front of them tell them what the ROV sees and where it is. Tony is monitoring the SONAR (lower middle monitor) to find a deep-sea camera system. Image courtesy of Sönke Johnsen. Download larger version (jpg, 3.2 MB).

For the past week, I’ve been watching Jamie and Tony, our two pilots, ‘fly’ their robotic deep-sea vehicle for about eight hours each day. It is not easy. First of all, they are not actually inside it. Instead, they control their ‘ROV’ (remotely operated vehicle) via a mile-long steel cable that goes from the sub itself to what looks like the back half of a U-Haul truck that is bolted to the deck of the ship. Jamie and Tony sit on two fairly comfy chairs in front of six television monitors that show different views from sub, including SONAR and navigation maps (Figure 1).

Figure 2: This is not a tropical sunset, though we have seen many beautiful ones. Note that you can see the stars, which you can’t during a real sunset. Instead, the ‘sun’ is actually a distant fire from an oil well, and the picture was taken at 11 PM under a dim crescent moon. The moonlight was just bright enough to make the sky blue, the way the sunlight makes the day sky blue. This photo was taken using a Nikon D700 from the bow of the RV Pelican. The ship was – as always – rolling in the waves, so the exposure had to be short, which shows you just how sensitive this camera is. It can literally turn night into day and is perfect for photographing bioluminescence.

Figure 2: This is not a tropical sunset, though we have seen many beautiful ones. Note that you can see the stars, which you can’t during a real sunset. Instead, the ‘sun’ is actually a distant fire from an oil well, and the picture was taken at 11 PM under a dim crescent moon. The moonlight was just bright enough to make the sky blue, the way the sunlight makes the day sky blue. This photo was taken using a Nikon D700 from the bow of the R/V Pelican. The ship was – as always – rolling in the waves, so the exposure had to be short, which shows you just how sensitive this camera is—it can literally turn night into day and is perfect for photographing bioluminescence. Image courtesy of Sönke Johnsen. Download larger version (jpg, 2.8 MB).

Jamie has a joystick that controls the sub via two propellers, and Tony controls the robotic arm using a miniature replica of the arm that he manipulates like a sculpture. Behind them sit five eager scientists, each pushing for Jamie and Tony to turn the sub in a different direction, to take a different photograph, or to pick up a different animal. We, as scientists are naturally interested in different parts of the project and in different animals, but there’s only one ROV.

Personally, I dislike having even one person talking behind me for a minute. How Tony and Jamie manage to have five of us chattering back there for eight hours a day without completely losing it is beyond me.

Figure 3: (Left) in situ photograph of a hormathiid anemone. (Right) The light emitted from the same animal. The emitted light is blue and comes from a mucous secretion. The animal is not actually red, but we briefly shine a red LED on it to show where it is.

Figure 3: The image on the left is an in situ photograph of a hormathiid anemone. In the image on the right is the light emitted from the same animal. The emitted light is blue and comes from a mucous secretion. The animal is not actually red, but we briefly shine a red LED on it to show where it is. Image courtesy of Sönke Johnsen and Katie Thomas. Download larger version (jpg, 99 KB).

Several things make this all even worse. First of all, the ROV is attached to the ship, which itself can be blown about by waves and wind. So it’s not uncommon for the ROV to arrive at a perfect site for photography and collections, only to be pulled backwards in a cloud of mud, like a small dog being pulled backwards on a leash.

This leads to problem two, which is the mud itself. The ocean floor is not like normal ground. It doesn’t have rivers to carry away dirt, and it doesn’t have tree roots to hold it in place. Instead, the debris from the thousands of feet of ocean above that has fallen for uncounted years simply accumulates in the deep piles of soft gray powder. Imagine not dusting your bookshelf for ten million years. So, every time the sub moves, every time it turns, and every time it stops, a cloud of this ooze is kicked up. Depending on the currents, it can take anywhere from five to 20 minutes to clear – leaving us to fill the time with discussions of critical matters like ‘why are so few state capitals the largest city in the state?’.

Finally, there is the darkness itself. The ROV is equipped with two banks of white LED lights, but even these can only show us things that are at most 40 feet away. The water swallows up light like a hole, so we wander around this enormous habitat never having any clear idea of where we are. GPS doesn’t work underwater and the SONAR analog of it can only give us a rough idea, so it’s much like hiking on a moonless night with a flashlight, except that the sun never rises and we never get to see the lay of the land. We go up and down hills, find strange little outcroppings, and see shapes in the distance, but how it all fits together is a mystery to us. It can be claustrophobic at times, and again I wonder how Jamie and Tony can do this day after day.

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