National Geographic : 1991 Jul
IDDEN GARDENS of color and movement opened for me when I dived beneath the ice to the shallow bottom near the shore of Admiralty Inlet. Forty feet beneath the surface at 290F, barely above the freezing point of salt water, I was delighted to find such tropical sights as a soft coral growing next to sea urchins (right) and a cardinal red shrimp perched on a kelp frond (middle). Water temperature, I know, is not a limiting factor in the growth of some corals. In fact, in the icy waters of both the Arctic and Antarctic an exten sive group of corals manages to survive. As long as the polyps have zooplankton to feed on, corals will grow surely, if slowly. Splashy sea anemones also find a niche, in this case on a boulder splotched with colorful coralline algae (facing page). These algae secrete a hard, cal careous substance similar to that produced by coral. I once watched with fascination as a small sea spider, disturbed by the glare of my diving light, moved away from me in crab like fashion only to be gobbled up by a sea anemone. Because the ice was still blocking the rays of the sun, most creatures on the bottom were in their winter trance, hardly moving at all. Fish lay on rocks oblivious to my approach. Gunnels-eellike fish-curled sleepily among soft corals. Shrimp, normally furtive and quick, remained motionless while I took their picture. When the ice disappeared and the sun lit the sea, animals that had been so docile now darted beneath rocks and vanished into kelp beds. In broken ice near shore I discovered a few cod hiding out. I captured the image of one reflected in an air bubble (bottom). During the season of open water, Arctic cod assemble in shallow-water schools half a mile long and so dense that the fish darken the seafloor beneath them. Why the fish mass in such numbers remains one of many mysteries in the life cycles of creatures that inhabit Arctic waters, a little understood ecosystem.