Aquatic ecosystem

An aquatic ecosystem is an ecosystem that is based in water, whether it is a pond, lake, river, underground water body, estuary or ocean. It comprises living aquatic organisms (eg: fish, plankton, annelids, etc.) which constitute the biotic factors of the ecosystem, as well as their physical environment which collectively can be referred to as the abiotic factor.

See also biodiversity.

Aquatic ecosystem are generally divided into two types - 1) inland aquatic, or 'freshwater'; Such ecosystems may be 'lotic' i.e. running water (spring, stream) or 'lentic' i.e. standing water (pond, puddles). Note that many inland aquatic ecosystems are not strictly 'freshwater' as saline ecosystems are common; however the term 'freshwater' has become standard shorthand in conservation biology literature for 'inland aquatic'. Subterranean ecosystems exist in many localities, and are particularly common in karst landscapes. Such ecosystems are at present widely neglected by established systems of protected areas.

2) marine water; deep water such sea and oceans.