Living organisms including humans are social when they live collectively in interacting populations, whether they are aware of it, and whether the interaction is voluntary or involuntary.
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
