Bayou-Diversity (4 August 2019) Freshwater mussels are a little known but critical component of the biodiversity of Louisiana bayous, streams, and rivers. Related to the much sought after oysters of the coastal area, freshwater mussels in Louisiana are not usually consumed by people today. Such was not always the case, however, as Native Americans routinely harvested large amounts of this high protein food. Piles of discarded shells or middens still mark the campsites of pre-historic peoples across the state.
Early in the 20th century, hundreds of factories were scattered up and down the Mississippi River utilizing freshwater mussel shells to make pearl buttons. Thousands of tons of shells were collected by commercial harvesters and sold to the button factories, which cut, drilled, and polished the pearlescent shell into buttons. Development of the plastics industry sounded the death knell for the button factories, as inexpensive plastic buttons soon replaced those made from mother-of-pearl. A renewed interest in freshwater mussels occurred when Japanese cultured pearl research revealed that tiny pieces of American mussel shells seeded into oysters made the ideal nuclei around which mother-of-pearl developed.
Ecologically, mussels are critical to many aquatic ecosystems as filters of suspended particles. They feed by siphoning water through hair-like structures called cilia and sorting out plankton and organic materials. Some researchers have found that healthy mussel populations can actually filter the entire volume of a stream in a short period of time. In doing so, they are vulnerable to pollutants from agricultural and industrial runoff. Chemicals, pesticides, and erosional sediments from poor logging and farming practices kill many mussel beds. Water quality soon deteriorates even further as the natural filters are eliminated.
About sixty-five species of mussels inhabit Louisiana waters. Three are considered endangered. Because of their sensitivity to environmental pollution, mussels are considered indicator species. When the health of a stream's mussel population declines, it usually means other native plants and animals in the same ecosystem will soon be disrupted – and so it goes right on up the line until humans are the ones impacted. (Adapted from “Bayou-Diversity: Nature & People in the Louisiana Bayou Country,” LSU Press)