200 Years. 200 Stories. Story 84: “The Patrick Principle ”

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photo of early environmental research
Dr. Ruth Patrick (third from the left) and her team during a 1947 biological survey of the Guadalupe River, Texas. Ewell Sale Stewart Library & Archives Coll. no. 2010-020.

The Patrick Principle

Dr. Ruth Patrick, founder of the Academy’s Limnology Department (now the Patrick Center for Environmental Research), turns 104 on Saturday, November 26. In honor of her birthday, we present a weekend of special stories about her remarkable career.

The term “Patrick Principle” was first coined by Thomas Lovejoy, a highly respected conservation biologist and influential advisor to international agencies and government leaders. It acknowledges the pioneering role Dr. Ruth Patrick has played in shaping the way science measures and understands human impacts on the environment. Dr. Patrick, who started her investigations of the environmental health of streams in the 1940s, recognized the shortcomings of common scientific practices of the day. These practices might identify whether a stream was grossly polluted with organic waste and starved of dissolved oxygen, but they couldn’t reveal much more than that. She realized the importance of knowing what a healthy stream looked like before determining whether or not the stream in question was affected by pollution or other environmental threats. To gauge a healthy stream, knowledge of its biological diversity was essential.

Dr. Patrick believed that biological diversity—the number, relative abundance, and ecological characteristics of species in an ecosystem—was a valuable indicator of the environmental health of streams. This idea has generated a rich body of aquatic research by scientists at the Academy and elsewhere. The principle also has been useful for studying, managing, and protecting other types of threatened ecosystems on land and in the oceans.

Find out more about Dr. Patrick, and stay tuned for more stories on her accomplishments.

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