Language is a system that consists of the development, acquisition, maintenance and use of complex systems of communication, particularly the human ability to do so; and a language is any specific example of such a system.
Like all ecosystems on Earth supporting animal and plant life, aquatic ecosystems need oxygen. However, oxygen availability in these systems is threatened by global warming and excessive input of nutrients such as from agriculture and wastewaters, known as eutrophication.
EN 
CS
DE
ES
FR
HU
IT
PL
PT
РУ
SK
TR
УК
AR
中文
