Ruth Patrick was a pioneering American limnologist, an expert in the study of freshwater ecosystems, who made significant contributions to the understanding of the biological and ecological components of aquatic systems.
The term “Patrick Principle” was first coined by Thomas Lovejoy in honor of Ruth Patrick's pioneering role in shaping the way science measures and understands human impacts on the environment. 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.