Symbiosis
Howard Hall
A red light began flashing in the viewfinder of my high definition video camera warning me that the camera battery was dying. Just as well, I thought to myself. I had been at 110 feet for over an hour and a half and had accumulated an equal amount of decompression. It was time to go up. Two enormous bull sharks passed lethargically over the reef in front of me as I struggled to move the big camera perpendicular to the current and toward the coral wall that rose to the surface of Fiji's Bega Lagoon. I was following a shallow channel in the reef where I found some protection from the powerful current. Occasionally, turbulence would spill down from the up-current edge of the channel and threaten to lift me up and throw me across the reef. I stayed as low and as close to the up-current side of the channel as possible. Because I was diving with a closed-circuit rebreather, I didn't worry about air supply. I could take my time and rest occasionally before moving on. A lemon shark swam down the channel to my left going in the opposite direction, unaffected by the current. Gray reef sharks and silver tip sharks were everywhere. I counted eight species of shark on this single dive. The coral reef wasn't much to look at in this part of Bega. The 1997 El Nino had left Fiji largely untouched while devastating coral reefs in many parts of the world. But the La Nina phenomenon that followed in 1999, bringing cold water to the Eastern Pacific, flooded the reefs of Fiji with fatally warm water. At 87 degrees, the algae that lives symbiotically within coral polyps was expelled. In the absence of the amber colored algae the coral bleached ivory-white. After a few weeks without the food produced photosynthetically by the algae, the coral died. Much of the coral here in Bega was dead but now, nearly two years later, I could see numerous fist-sized clusters of new coral growth. Fiji's reefs were beginning to recover. I paused to rest for a minute as another eddy of current reached down into the channel. I looked down at the sand near the base of the reef and noticed a spotted shrimp goby valiantly guarding its burrow while a small yellow shrimp labored to remove sand swept into the burrow entrance by the current. This was a classic symbiotic relationship. The shrimp maintains the burrow for both itself and the goby. The goby stands guard and warns the shrimp of approaching danger. Each animal needs the other to survive. Certainly, at some point in their evolution, each species existed alone. But then, one day, a shrimp and a goby found they had a better chance of mutual survival if they lived and worked together. Natural selection reinforced this partnership and today the lives of shrimp and goby are inexorably intertwined. I moved forward and reached the base of the wall and began moving up toward my first decompression stop. I found a comfortable notch in the reef at sixty feet and paused for two minutes next to a pale yellow anemone that was home to a pair of orange-fin anemonefish. As I watched, the anemonefish plucked a tentacle off the anemone and ate it. I was surprised. I had always understood that the anemone and anemonefish relationship was strictly mutualistic - a symbiotic relationship where both species benefit. Obviously, there is an element of parasitism involved, at least in this case. Still, no animals are better known for symbiosis than the anemonefish and the anemone. When I first started diving I was thrilled to see my first anemonefish, not only because these creatures are beautiful, but because they so well demonstrate what I thought was the rare and unusual relationship of symbiosis. Now I know that symbiosis is more the rule than the exception in the natural world, especially on a coral reef. It's literally everywhere you look. I glance around and see a remora riding on a white tip reef shark, a parrotfish is being cleaned by a blue-stripe cleaner wrasse, a tiny hermit crag walking by with a sponge on its shell, and a shrimp is cleaning a large moray eel. Even the anemone, which is home to the anemonefish, is dependent on the same kind of photosynthetic algae in its tissues that coral depends on. Literally every animal I can see, in some way or at some time, engages in and depends upon symbiosis. In order to survive, these animals must cooperate with each other. As I moved up the reef to my next decompression stop, I realized there was one creature on this reef who did not engage in symbiosis. Me. Perhaps humans evolved too quickly or are too young a species to have developed symbiotic bonds with other species. Perhaps our species is just a flash-in-the-pan destined to live fast and die young. But as I thought about it, I realized I was wrong. Isn't our relationship with dogs, horses, cats, and many domesticated animals symbiotic? Domestic dogs receive food and shelter. Human dog owners receive companionship. Both benefit. Certainly, both humans and dogs could exist without each other. But that doesn't disqualify the relationship as symbiotic. Many marine creatures engage in cleaning behavior, but it has been proven that the same animals can survive without cleaning or being cleaned. The quality of their lives is simply better if animals cooperate with each other. I moved up the reef to thirty feet and had just settled down to pass another fifteen minutes when I heard the sound of scuba bubbles. Divers were jumping in from the Aqua-Trek dive boat and beginning their descent to 100 feet. Michele and Nai'a divemaster Cat Holloway were with them. As they descended Michele called on her OTS underwater communications system. "Hello, where are you?" she said. "Behind you at thirty feet on the reef," I responded seeing her fluorescent yellow Scubapro split-fins glowing against the blue water. Michele and Cat turned, saw me, and waved. "Have a good one," I said. Then I watched as they and a dozen other divers drifted down toward the base of the reef. A moment later I heard a splash and looked up to see Brandon Paige and two of his divemasters descending with huge buckets of bait. The second shark dive was about to begin. I had begun my dive with the group during their first shark dive of the day. After Michele, Cat, and the other divers ran low on air and ascended, I stayed down and continued filming the sharks while they sat on the boat taking an hour of surface interval time. Now I was decompressing as they began their second dive. I planned to be finished decompressing about the time they returned to the boat. I pushed off the wall and swam out over the divers and watched the action below while hovering at twenty feet. Aqua-Trek organizes one of the most spectacular shark dives I have seen. They routinely attract bull sharks, lemon sharks, and tigers. As I watched the action below I noticed that the divers' bubbles were coming straight up and that I had no trouble hovering overhead. The current had stopped.
The sport divers took refuge behind a coral wall as Brandon and his divers began dumping bait out on the bottom. Gray reef sharks, silver tips, and white tip reef sharks were already taking the baits even as the divers dumped it from the buckets. A moment later the bull sharks moved in. It was a spectacular sight for divers of any experience. As strobe lights began to pop, I moved back toward the reef. It suddenly occurred to me that this shark feed represented another symbiotic relationship. As shark populations decline worldwide, scientists and conservationists struggle with measures for protecting these spectacular predators. Yet the same scientists and conservationists tend to discourage dive operations from attracting sharks with baits. I then realized how completely backwards that attitude is. Given the reality of human population growth and commercial fishing pressure on marine environments, perhaps the only hope for sharks is to embrace a symbiotic relationship with man. That is exactly what I see happening below at the base of the reef. Symbiosis. Humans get pleasure and underwater photographs of sharks. The sharks win advocates for shark preservation. If you never see bull sharks, how are you going to know when they are gone and why should you care? The bull sharks below have guardians whose pleasure, and in some cases, livelihood, is dependent upon the survival of the sharks. In an ideal world humans would be willing to protect wildlife purely because it's the right thing to do for the environment and long-term health of the planet. But as humans exploit ever more remote corners of the planet, profiting from the destruction of wildlife and wilderness, it has become clear that our relationship with wilderness is far from ideal. It has become obvious to me that in order for wildlife and wilderness to survive, a mutually beneficial economic relationship must be found. We shouldn't be discouraging divers from swimming with whales, dolphins, sharks, and other wild creatures. We should be encouraging it. We should embrace symbiosis. Unfortunately, shortsighted politicians have banned shark dives in Florida in a knee-jerk reaction to the attacks that happen each year along Florida's beaches. I suddenly realized that this ban is bad, not only for the dive operations that hosted the dives, but is even worse for the sharks. Sharks loose visibility and value among their human partners. Without witnesses and advocates these predators become much more vulnerable to exploitation by commercial fisheries. "Tiger shark, tiger shark," Michele yelled through her comm. system. I pushed off from the wall and began dropping toward the group of divers below, eager to get a shot of a tiger shark. As I approached the bottom I saw an enormous female tiger feeding on the bait Brandon had set on the reef near the divers. I switched the camera on and set the lens to full-wide. As I descended I watched the tiger shark grow in the viewfinder until it filled the frame. A good shot of a tiger shark would be a really valuable addition to my high definition library. Symbiosis. I triggered the run switch and was thrilled to watch the shark turn toward me. Then the battery died. |
