Conservation is the preservation or efficient use of resources (in an efficient or ethical manner), or the conservation of various quantities under physical laws.
Fish populations are declining in many of Europe's inland waterways, partly as a result of exposure to aquatic pollutants such as from wastewater treatment plants.
EN 
CS
DE
ES
FR
HU
IT
PL
PT
РУ
SK
TR
УК
AR
中文
