Dress warmly, hold your breath, and take a dive . . . You pierce the surface of Baikal at a soft angle and slip like the low rays of the high-latitude sun into a prism of liquid glass. The water molecules release their bonds with each other to embrace you. Sunlight follows you, wiggles, and scatters; the photons themselves become liquid. Sound becomes a liquid, too, thick and syrupy. Gravity loses its bearings and presses at you from all around. Normal reference points fall away— up and down, left and right—your sense of where you are comes only from subtle changes in light, temperature, and pressure. This will take some getting used to. But not to worry, here in the world’s oldest lake, still in its youth at twenty-five million years, you’ve got nothing but time. And if you put on your special magnifying goggles, you’ll see that you’ve got plenty of company, as well. You’re surrounded by a haze of tiny creatures, each no longer than a millimeter and a half. They’re Epischura baicalensis, those elfin shrimp that float through the lake, sucking massive Baikal through their little digestive tracts, feeding on algae and bacteria, pulling out impurities, and helping to keep the lake clean and clear. Epischura baicalensis are members of a group of organisms known as zooplankton—tiny animals and larva that drift and swim through the water, buffeted about by waves and currents. The miniscule creatures that make up zooplankton live everywhere, in just about every body of water on earth, and like Epischura baicalensis, many of them are little shrimp, or copepods. But Epischura baicalensis live nowhere else, and apparently can’t live anywhere else. It’s said that they can’t live even in a glass of Baikal water removed from the lake. Perhaps they die of homesickness. The water surrounding you as you float in Baikal is about as close as you can get in nature to pure H2O. It’s what aquatic scientists call “oligotrophic”— there’s very little in the way of nutrients and minerals running off into it from the surrounding landscape, and so a very limited supply of some of the basic building blocks of life.
Effect of nutrient availability on carbon and nitrogen incorporation and flows through benthic algae and bacteria in near-shore sandy sediment
