Genetics is the study of genes, genetic variation, and heredity in living organisms. It is generally considered a field of biology, but intersects frequently with many other life sciences and is strongly linked with the study of information systems.
It is an article of passionate faith among 'politically correct' biologists and anthropologists that brain size has no connection with intelligence; that intelligence has nothing to do with genes; and that genes are probably nasty fascist things anyway.
Richard Dawkins, in The Economist, Vol. 328 (1993)
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.