Freshwater ecosystems are the most biodiverse and most threatened on Earth. Protecting rivers, lakes, and wetlands is essential not only for conservation but for the welfare of countless aquatic animals.
The collapse of freshwater ecosystems causes welfare harms at massive scale. Fish trapped below dams or stranded in drying rivers experience lethal stress. Pollution-caused oxygen depletion kills entire fish communities through suffocation. Invasive species displace and outcompete native animals that are ecologically suited to local conditions. The suffering involved in ecosystem-scale freshwater degradation is diffuse and hard to quantify, but it is real and enormous. Protecting freshwater systems is among the highest-leverage actions available for reducing wild animal suffering at scale.