ECOSYSTEMS

Loch Lomond in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period.[54]
All forms of life interact with the environment in which they exist, and also with other life forms. In the 20th century this premise gave rise to the concept of ecosystems, which can be defined as any situation where there is interaction between organisms and their environment.
Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated way.[55] The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.