An unexpected find and very exciting moment for researchers exploring what lies beneath 740 meters of ice in Antarctica…fish! An amazing find given the perpetual darkness and cold.
In an expedition sponsored by the National Science Foundation, scientists and ice drillers bored a hole through the Ross Ice Shelf near the coast of Antarctica, 850 kilometers from the closest place where there is sunlight. The area is known as the grounding zone, which is in essence a subglacial beach. According to a quote from glacial geologist Ross Powell (Northern Illinois University) published in Scientific American, “I’m surprised. I’ve worked in this area for my whole career. You get the picture of these areas having very little food, being desolate, not supporting much life.”
During their 20 hour observation, the research team saw 20-30 of the fish shown in the image above (approximately the size of a butter knife) in addition to two types of smaller fish, a black one and an orange one. They also discovered amphipods (related to shrimp) and other marine invertebrates they have yet to describe. Samples of the seawater showed very little life in the way of microbes. You have to imagine that other sea life would consume much of the plankton before it reached this spot, over the course of 6-7 years based on estimates. The sea floor did not contain any mud-dwelling creatures or anything that would be considered very nutritious. Rather, what was discovered were several different animal species that could move around to find food.
It is possible that animals living in under the glacier use chemical energy, such as minerals from the ice, ammonium, methane, etc from the Earth instead of sunlight for energy. Bacteria are known to use alternate energy sources such as these and may serve as food for the crustaceans which could then serve as food for the fishes, according to Dr. Arthur DeVries a Comparative Physiologist at the Univerity of Illinois at Urbana-Champaign who was not involved in the expedition. Moreover, fishes may feed on the offspring of other fishes. Of note, Dr. DeVries is also this year’s Krogh Distinguished lecturer, which is awarded by the Comparative and Evolutionary Physiology section of the American Physiological Society at the upcoming Experimental Biology conference in Boston. I can’t wait to hear his seminar!
A string containing sensors was also lowered into another hole by Dr. Slawek Tulaczyk (University of California-Santa Cruz) with the goal of measuring temperatures within the ice and water at varying heights, tidal flows, the flow of subglacial rivers, as well as the flexing of the ice that occurs with the tides. The purpose of these measurements is to measure the amount of heat and mechanical stress occurring in this part of the glacier in an effort to understand how involved glaciers from this area are in the rising sea levels.
What I want to know is why do these fish still have seemingly normal looking eyes? Fish living in darkness are sometimes blind. Perhaps these fish are newcomers to the area? Perhaps they have adapted the ability to see in the dark somehow? These fish must also produce anti-freeze proteins like other cold-adapted fish. Without a live specimen, we may have to continue guessing. Fascinating!