by Edith Widder
A lot can be learned about the kinds of stimuli that excite bioluminescence by observing a dolphin swimming through bioluminescent plankton. For a long time, the only way to record such observations was either verbally or artistically. The famed graphic artist M. C. Escher, best known for his lithographs and woodcuts of impossible constructions, also did more realistic works, including one entitled Dolphins in Phosphorescent Sea.*2 This 1923 woodcut is a white-on-black depiction of the brilliant bow wave of a ship at night as it plows through bioluminescent plankton, with dolphins swimming in front of it. Each dolphin is outlined by the bioluminescence it excites, from the tip of its nose to the tip of its tail, which leaves an undulating luminescent trail. There are also two dolphins, one to either side, that are leaping clear of the water; one is creating a forward-directed corona of spray as it reenters the water, and the other is creating a backward-directed corona as its tail splashes down.
This depiction was at odds with many published scientific descriptions that reported an absence of bioluminescence on a dolphin’s body. However, as it turns out, Escher got it right. With the recent advent of low-light-sensitive cameras, it has been possible to record scenes very similar to the one he depicted. Analysis of these videos reveals that the brightest light is associated with the spray generated when the dolphin breaks the surface. There are brilliant trails of light coming off the fins and tail (spots where flow transitions from laminar to turbulent*3), but there is also light visible everywhere on the dolphin’s body. The reason this was not reported by many science observers may be that they were not sufficiently dark adapted to see the dimmer bioluminescence associated with the sleek dolphin torso. In any case, the key finding from such analyses is that the amount of bioluminescence seen is simply a function of the volume of water being stimulated at any given moment.
Since the bioluminescence that is stimulated is a consequence of both the shape and the swim pattern of the swimmer, different fish have different bioluminescent signatures. This is a characteristic that nighttime fishermen exploit. I learned of this from one old-timer who used to fish the Florida waters near where I live. He described how back in the day, when dinoflagellate bioluminescence was so abundant in the local estuary that the fishermen described it as “fire in the water,” they could identify the fish by the luminous patterns they made.
If fish are easily spotted and identified by the distinctive patterns of light they produce, then it should be no surprise that the same is true for ships and submarines. In fact, because of the enormous volumes of water they excite, some of these trails can be seen from great heights above the ocean.
Astronaut Jim Lovell, best known as the commander of the ill-fated Apollo 13 mission, could bear witness to the visibility of bioluminescence from on high, based on a close call he once had as a U.S. Navy pilot flying Banshee night fighters in 1954. He had been on a training mission off the aircraft carrier Shangri-La in the Sea of Japan. He finished his flight and had begun following what he thought was the homing signal leading him back to the carrier when he realized he was heading in the wrong direction. The signal he was tracking was coming from mainland Japan and coincidentally broadcasting at the same frequency as the carrier’s. Once he realized his mistake, he needed to try to communicate with the carrier. To do so required reading the communication codes written on the pad of paper strapped to his thigh.*4 The trouble was, the cockpit lights were too dim to read by, so he flipped on a small light that he had jury-rigged into the airplane’s electrical receptacle. The result was a short circuit—a bright flash of light followed by a total blackout of all of his instrument readouts. Disaster!
Without his instruments, he had no hope of locating the carrier. As he sat in the darkness, contemplating the grim truth that if he had to ditch, his odds of survival were nil, he desperately scanned the sea below for any sign of the carrier. It was like trying to find a needle in a haystack…in the dark. But in the end, it was the darkness that saved him, because the total blackout allowed him to spot a faint shimmering trail of light in the water. It was the bioluminescence stimulated by the long, turbulent wake the carrier left behind. He recognized it for what it was—his illuminated path to salvation—and followed it all the way back to the Shangri-La.
Being able to see bioluminescence churned up on the surface by an aircraft carrier from an airplane is one thing, but how about that which is stirred up by a submarine from a satellite? Whether or not this was actually done I can’t say, but it was theoretically possible, and definitely doable from P-3 Orion airborne submarine hunters, which is why the U.S. Navy cared and why my fascination with bioluminescence turned out to be fundable.
During the cold war, submarines became critical for intelligence-gathering efforts on both sides. Most stories of the behind-the-scenes drama associated with playing cat-and-mouse games underwater remain classified, but some of these were revealed to the public for the first time in the book Blind Man’s Bluff, by Sherry Sontag, Christopher Drew, and Annette Lawrence Drew.
The audaciousness of the missions was breathtaking. They included sneaking along Soviet coastlines, periscope up, looking for posted signs that were the Russian equivalent of DO NOT ANCHOR—CABLE HERE and then following the cable offshore and securing an eavesdropping device to it. They also involved learning to acoustically track increasingly quiet Soviet missile subs called boomers that could sneak up on our coast and unleash nuclear Armageddon in the form of ballistic missiles.
The prime directive, for both the U.S. and Soviet submarine fleets, was “Avoid detection at all costs.” Staying submerged and quiet was key to accomplishing this, but it wasn’t a guarantee, which is why both sides were pursuing less traditional modes of detection that fell under the heading of nonacoustic anti-submarine warfare (ASW). This was not a new idea. In fact, during World War II, when German U-boats were slipping into the Gulf of Mexico and torpedoing freighters within a hundred miles of Florida’s coast, the Germans were well aware of the threat of detection that bioluminescence posed. One U-boat commanding officer, Captain Reinhard Hardegen, deemed it the primary threat and warned fellow commanders, “The most dangerous feature of American water is marine phosphorescence at night—because of aircraft or destroyers, be aware that if you travel at periscope depth, vortices off your screws and cannon will show up as phosphorescence and betray your position.”
Because bioluminescence could reveal the presence of submarines, both the Soviets and the U.S. Navy put significant effort into developing a predictive capability for the phenomenon, in order to know where and when they or their enemy might be most vulnerable to detection. Initially, this didn’t seem like any great challenge.
Measuring bioluminescence is easy, as the first investigators who dropped light detectors into the ocean discovered. Just lower a sensitive enough light sensor over the side of a ship and wiggle it around and you’ll record bioluminescence. In fact, shortly after investigators recognized that the amount of light they were measuring was related to the sea state, they started designing systems that permitted greater control of the stimulus. All of these were called bathyphotometers (BPs), which simply means “deep” (bathy) “light meter” (photometer).
BPs came in a great many shapes and sizes, but the most typical design used a pump to pull water into a darkened chamber, where a spinning propeller or a narrow constriction stimulated bioluminescent critters to flash so their light output could be recorded. The problem was that the light measured depended on the size of the detection chamber, the method of stimulation, the flow rate, and how much the water was churned around before it got into the detection chamber. This meant that numbers measured by one kind of BP couldn’t be compared with those measured by another. Also, most BPs had low pumping rates (a liter per second or less), which raised concerns that the only kind of bioluminescence they were measuring was probably from dinoflagellates and not other, faster and much brighter emitters, such as krill, that could easily e
vade such wimpy flow fields but might contribute significant light when colliding with an onrushing submarine.
All of these various concerns came to a head in 1981 when, at the request of the oceanographer of the Navy, a panel of university and Navy experts convened to propose improvements to BP design. Based on their recommendations, a request for proposal (RFP) was issued to see who might come up with a design that could address all the Navy’s concerns and become the U.S. Navy standard system for measuring bioluminescence around the world.
Jim Case submitted a proposal, and, since much of what he was advocating was based on my thesis research, he included me as co–principal investigator. Being a co-PI on a grant of this magnitude so early in my career was a huge deal. This was big money—over half a million dollars to start with, and more to follow—and potentially high-profile, but only if it worked. According to the rules of credit and blame in research, success is attributed to the supervisory brilliance of the adviser, and failure to the utter incompetence of the grad student. That formula goes double for postdocs. If this project failed, it could be reputational suicide. Therefore, when I learned we’d been awarded the grant, I felt a weird mixture of glee and angst—sort of like the guy who finds out he won the lottery and then realizes he’s misplaced the ticket.
Although Case and I were nominally co-PIs, he had his hands full serving as UCSB’s associate vice chancellor of research, which meant the brunt of the project fell to me. I had experience with instrumentation development and a solid enough background in the science needed, but I had never managed a project of this scale. There were many personalities and moving parts, and at numerous points along the way I thought the whole damn thing was going to wind up in an epic fail.
Our guiding principle was to have the biology drive the engineering. To make sure commonplace fast swimmers couldn’t escape measurement, we used the top swimming speeds of krill to calculate what the pumping speed needed to be. The trouble with that requirement was that the faster the flow rate used, the shorter the residence time of the light emitter in the chamber, which meant that with many animals, we couldn’t measure their entire flash. If we used a standard-size detection chamber, a krill would go rocketing out the exhaust before we’d had time to measure more than a fraction of its light output.
To get around this problem, we made the detection chamber into a tube over four feet long and almost five inches in diameter. That created three more challenges: how to force water through the tube at high speed, how to stimulate the bioluminescence in some calibrated fashion, and how to measure it (also in some calibrated fashion). We settled on a high-speed pump at the back end of the tube that pulled water in through a steel grid at the front end, thereby producing a well-defined plane of stimulation—sort of like a SPLAT screen but coarser.
In order to collect all the bioluminescence in an unbiased fashion down the length of the tube, we embedded more than seventy fiber optics that collected the light and directed it to a photomultiplier tube. We also designed a freely rotating light baffle in front of the grid to keep out stray light from the moon or ships, while minimizing pre-stimulation of bioluminescence before the water hit the stimulation grid. This feature was deemed especially important because of what I had learned during my thesis research on Pyrocystis fusiformis about how much brighter the first flash is than subsequent flashes, which meant that our measurements would be drastically reduced if the sources were stimulated to flash before entering the test chamber.
Since this was a Navy project, it required a Navy-worthy acronym. I struggled for a while before settling on one I was happy with: the High Intake Defined Excitation Bathyphotometer, or HIDEX-BP, was a name that incorporated all the system’s most original features. I thought it had a nice ring to it. The lead software engineer on the project, Steve Bernstein, a.k.a. Bernie, disagreed. He thought it sounded too much like Riddex pest repellent, which is why, shortly after I came up with the name, the control screen for the HIDEX software started displaying pop-ups advertising “HIDEX for all your pest control needs.” Theoretically, these were removed before the system was delivered to the Navy, but, given Bernie’s sense of humor, I was never completely confident they wouldn’t reemerge at some later date.
The key to designing a good measurement system is being sure you know what the numbers mean. Meeting this challenge was daunting and involved many steps, one of which found me dangling over the edge of a large fiberglass septic tank (new, not used) with the top cut off in order to create a test tank big enough to hold our prototype BP. The edge of the fiberglass was cutting into my chest, and I was sweltering under the big sheet of black plastic that covered the tank, to keep out stray light, while my arms were going numb in the chilly seawater, where I was slowly releasing bioluminescent dinoflagellates into the mouth of the BP. This was one of many points along the way to developing the HIDEX where I found ample opportunity to reevaluate my career choices. In no way did this resemble the popular view of the everyday life of a marine biologist—swimming with dolphins during the day and sipping mai tais on a tropical beach at sunset.*5
The initial field test for the HIDEX was my first experience serving as chief scientist on an expedition, and although I had plenty of familiarity with Murphy’s law from previous seagoing adventures, I felt like Murphy outdid himself on this one. The seas were high, the vessel unstable, and on the first night, the combined smells of eau de diesel and rancid oil from fish frying in the mess left most of my team seasick. Once we finally got enough operational hands to deploy the HIDEX, it didn’t work. When we troubleshot it back on deck, the consensus was that it didn’t run when wet or in the dark. Rather than report this state of affairs back to Dr. Case, we agreed that the better course of action would be to force the ship’s captain to take us to Baja, where we would open a bar and hang the HIDEX out front, disguised as a beer keg, with a sign reading HOT BEER, LOUSY FOOD, BAD SERVICE, HAVE A NICE DAY.
Battlefield humor, usually at one a.m., when everyone was punchy and nothing was working, became one of the hallmarks of the brutal campaign to get the HIDEX operational. It was very much a team effort that required maintaining a “plays well with others” factor, which we managed pretty well most of the time. Nevertheless, this was a big project that went through the standard phases of (1) enthusiasm, (2) disillusionment, (3) panic, hysteria, and overtime, (4) hunt for the guilty, (5) punishment of the innocent, and (6) reward for the uninvolved.*6 The by-product for me was unrelenting stress, only partially eased by a steady diet of Tums, which eventually escalated to chugging Maalox straight out of the bottle.
Ultimately, though, HIDEX was deemed ready for its first Navy mission. This was to be a transatlantic crossing, making bioluminescence measurements in the top five hundred feet of the ocean from the Canary Islands, off the northwest coast of Africa, to Florida. There were five of us making the crossing: me, Dr. Case (whom I was now allowed to call Jim), Bernie, Mike Latz, and our electrical engineer, Frank. It was a classified mission to be carried out aboard a Navy oceanographic vessel, the 285-foot USNS Kane.
At the outset of the HIDEX project, I had been issued a security clearance and was familiar with the restrictions this entailed, but this mission brought a new level of security that struck me as over-the-top. While I was allowed to tell my husband the name of the ship and the name of the port we would be leaving from, for some reason I was not permitted to tell him both things on the same day. I made the security officer repeat that instruction just to be sure I heard it right. Apparently it was a carryover from World War II, when concerns about intercepted transmissions drove the instigation of precautions about not including multiple pieces of key intel in the same missive. It was difficult for me to imagine how any of what we were doing could possibly be of interest to a foreign power, but it was.
This interest became evident soon after we boarded the Kane in the port of Las Palmas. I was in the ship’s lab, talking to Bernie, when the
captain came in and, gesturing toward the HIDEX on the back deck, said, “You should probably throw a tarp over that thing. It’s attracting too much attention.” We walked out onto the fantail to see what he was talking about and were astonished to discover a huge Soviet oceanographic vessel tied up directly behind us at the dock. Up on its bow, a couple of guys with cameras and telephoto lenses were taking pictures of our baby.
Our next hint of more than casual interest came with the temporary disappearance of the shipyard’s welder. Since the Kane didn’t have a qualified welder on board, we had to use the shipyard’s guy to weld the BP’s winch onto the deck. At one point we lost track of where he was, and I was surprised and slightly alarmed when I discovered him in the lab, leaning over Bernie’s shoulder and pointing to the HIDEX software, asking questions.
Although we might have been able to persuade ourselves that both of these incidents had innocent explanations, the next turn of events made such an interpretation more challenging. On a Navy vessel, the radio shack is classified space, and only those with appropriate clearance are allowed entry. The night before we sailed, our radioman went ashore for some R&R and ended up going on a bar crawl with a few of the Soviet ship’s crew members. Copious alcohol consumption led to the Soviets convincing him to invite them aboard the Kane and into the radio shack. In the debriefing that followed this incident, the seaman claimed that they had subsequently invited him aboard the Soviet vessel, but the last thing he said he remembered was walking up their gangway. When he came to, the police were fishing him out of the harbor. Our team was unaware of any of this until the following morning, when we saw our radioman being led away in shackles.
This was no minor occurrence, especially in the captain’s view. He was convinced the whole thing was going to be a major blemish on his record, and he blamed us and the HIDEX. Therefore, while we waited for a new radioman to replace the one we had lost, the captain took the opportunity to hold an all-hands-on-deck meeting to talk about recent events.
