Freshwater bivalve

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Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails.

The majority of bivalve molluscs are saltwater species that live in the marine habitats, but a number of families have evolved to live in fresh water (and in some cases, also in brackish water). These belong to two different evolutionary lineages, i.e. freshwater mussels and freshwater clams, and the two groups are not closely related. Freshwater bivalves have a simple morphology that varies among taxa, and are distributed around most regions of the world.

Freshwater bivalve species vary greatly in size. Some pea clams (genus Pisidium) have an adult size of only 3 mm (0.12 in). In contrast, one of the largest species of freshwater bivalves is the swan mussel from the family Unionidae; it can grow to a length of 20 cm (7.9 in), and usually lives in lakes or slow-flowing rivers. Freshwater pearl mussels are economically important as a source of pearls and mother of pearl. While some species are short-lived, others can be quite long-lived, with some species registering longevity in the hundreds of years. ^[1]

Freshwater bivalves can thrive in many different types of habitats, ranging from small ditches and ponds to large lakes, rivers, canals and wetlands. The ecology of freshwater bivalves varies among species with regards to differences in reproduction and predation. In spite of their variety of ecosystems, freshwater bivalves are some of the most endangered species on the planet. In North America, for instance, many freshwater mussel species have gone extinct, and of those remaining, 65 percent are rated as endangered, threatened or vulnerable. Droughts, forest clearing, farming, use of dams for water management, and changes in water temperature can all pose threats to freshwater bivalve populations. Restoration efforts focus on rebuilding lost mussel populations in the wild and using those mussels to improve and protect water quality and restore broader ecosystems.^[2][3]