Ecosystem
The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined the spatial extent of ecosystems using the term ecotope.
John Todd (Canadian biologist)
Todd and his colleagues were some of the first people to actually create miniature ecosystems, largely self-perpetuating, which applied ecological principles to address human needs. 
Todd's approach is one of biomimicry, in which a complex natural ecosystem such as a marsh is studied, recreated and adapted.
Learning from the natural system, the ecological designer combines micro-organisms, fish, and plants into a functionally complex system that is capable of carrying out tasks such as bioremediation and phytoremediation.