The original definition is from Ernst Haeckel, who defined ecology as the study of the relationship of organisms with their environment. In the intervening century and a half, other definitions of ecology have been proposed to reflect growth of the discipline, to found new specialties, or to mark out disciplinary territory.

Ecology is the study of the environment, and helps us understand how organisms live with each other in unique physical environments.

Around the United States, scientists are increasingly worried about rising levels of salt in freshwater wetlands, rivers, and lakes, even in much larger bodies like the Great Lakes.