The term ecosystem was coined in 1930 by Roy Clapham to mean the combined physical and biological components of the environment. Ecosystem is the integrated study of biotic and abiotic components of the environment and their interaction within the given ecosystem framework.
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving (abiotic) or physical components of the environment with which the organisms interact, such as air, soil, water and sunlight.
Hence ecosystem can be defined as functional unit comprising all the organisms in a particular place interacting with one another and with their environment, interconnected by an ongoing flow of energy and a cycling of materials.
For example, Marine or aquatic ecosystem will include all the species of organisms, their lifecycles and their interconnectedness with each other and with marine environment below the sea.