There are always examples of degradation, but there are very few examples of ecosystems left that are that pristine.
ecosystem ec·o·sys·tem (ěk'ō-sĭs'təm, ē'kō-)
An ecological community together with its environment, functioning as a unit.
A community of organisms together with their physical environment, viewed as a system of interacting and interdependent relationships and including such processes as the flow of energy through trophic levels and the cycling of chemical elements and compounds through living and nonliving components of the system.
A collection of living things and the environment in which they live. For example, a prairie ecosystem includes coyotes, the rabbits on which they feed, and the grasses that feed the rabbits.
Note: Chemical substances move through ecosystems on the Earth in cycles (see carbon cycle).