Alfred Clarence Redfield (November 15, 1890 in Philadelphia – March 17, 1983 in Woods Hole) was an American oceanographer.
He is especially known for having discovered the Redfield ratio, which describes the ratio between nutrients in plankton and ocean water. In 1966, he received the Eminent Ecologist Award from the Ecological Society of America. His research was used by James Lovelock in the formulation of the Gaia hypothesis, that "Organisms and their environment evolve as a single, self-regulating system." From 1918 to 1924, Redfield worked with Elizabeth M. Bright on studies that involved the effects of radiation and Nereis. In collaboration the team published 12 papers.
During his doctoral research, he studied horned toad and what controls the skin coloration. He found out that a “stress” hormone called adrenalin is what controlled the skin coloration. He later studied what effect did X rays and radium radiation have on the physiological action. He carried out this study by experimenting on living tissue to see the effect it had from ionization produced by radiation.
Later during his graduating years, he got inspired to work in the study for Marine Biology. He studied the how the respiratory works in the blood of marine invertebrates. He found hemocyanin, which is the blood pigment of many invertebrate species and how it binds oxygen and its physiological behavior.
During the 1930s, he discovered that the ratios between phosphorus, nitrogen and carbon of marine plankton are indistinguishable with their proportions in the open ocean. This idea was used to explain some characteristics of the carbon life cycle in the sea. This was one source of his famous aphorism, “Life in the sea cannot be understood without understanding the sea itself.”
In the 1940, when World War II was taking place, there were some changes that occurred to the Oceanographic. Redfield was selected as the assistant director. At this time he focused on studying how to protect submarines that were submerged from surface ships and aircraft and the issue of polluting ships in marine invertebrates. He and his colleague came to realize that submarines that have been submerged can regulate its resistance by shutting down its motors and stay quiet for hours. He then came up with an idea of installing bathythermographs which became a huge success. A.C. Redfield Lifetime Achievement Award, presented annually by the American Society of Limnology and Oceanography