Freshwater mussels are among the most imperiled groups of animals globally. Their welfare science is nascent, but their conservation and role as ecosystem engineers deserves attention.
Freshwater mussel welfare science is at an early stage, with uncertainty about whether these invertebrates have sufficient nervous system complexity for sentience. Their welfare significance lies primarily in their ecological role — as filter feeders processing millions of liters of water annually, their population declines degrade water quality for all organisms in river systems. If freshwater mussels have any capacity for negative experience, the threats they face — smothering by sedimentation, poisoning by agricultural runoff, and physical damage from invasive zebra mussel colonization — would represent significant welfare harms. Conservation of freshwater mussel populations protects the river ecosystem welfare of all organisms depending on clean, structurally complex river habitat.