margaritifera

Margaritifera is a genus of freshwater mussels in the family Margaritiferidae. The most widely known species is Margaritifera margaritifera, the freshwater pearl mussel, once common in clean rivers across northern Europe and parts of North America. Other species in the genus occur primarily in the Northern Hemisphere.

Members have elongated, gently curved shells that are usually brown or greenish and are adapted to a sedentary, filter-feeding lifestyle. Like other unionid mussels, Margaritifera species are long-lived and spend much of their lives buried in sediment or on the riverbed. They rely on clear, well-oxygenated water and stable substrates, and are sensitive to sedimentation and habitat disturbance.

Reproduction involves the release of free-swimming larvae called glochidia, which must parasitize specific fish hosts to complete development before settling as juvenile mussels. This host-dependency makes Margaritifera populations vulnerable to declines in suitable fish species and to changes in river ecosystems.

Distribution covers temperate rivers and streams of the Northern Hemisphere, with natural ranges in Europe and North America. Across many regions, populations have declined due to pollution, siltation, damming, and other hydrological alterations that degrade habitat and disrupt host-fish dynamics.

Conservation status varies by region, but Margaritifera margaritifera is listed as Endangered on the IUCN Red List in many areas. Protective measures focus on habitat restoration, water-quality improvements, protection of fish hosts, and, where feasible, captive breeding and reintroduction programs. Historically, the species’ value as a source of natural pearls contributed to extensive exploitation, though contemporary conservation emphasizes ecosystem health and biodiversity.