Dr. Lowman’s latest Nature’s Secrets column in newsobserver.com:
What group of species is more common in North America than anywhere else?
Freshwater mussels. But this unique group of organisms rarely reaches the headlines or even reaches the center of discussion in school biology classes. Even more amazing is the fact that, of the 297 species found on our continent, two-thirds are concentrated in the Southeastern United States because of the region’s unique geology and relatively stable environment over the past 60 million years. Mussels provided an important food source for Native Americans, fostered the button industry in the 1800s, and constitute an essential part of freshwater food chains.
Mussels operate as filter feeders, removing bacteria and algae from water, which ultimately contributes to water quality. Of the 10 to 700 animals found in one square meter of stream bottom, each one filters approximately one liter of water per hour – essentially providing a free water-filtration system for our freshwater streams.
But mussels are in great danger. Twenty-five species already are extinct, and about 75 percent of mussel species are at some level of peril. The biggest threat to mussels was the widespread construction of dams in the early 1900s, and more recently, deforestation and mining that create muddy waterways. Mussels cannot survive in these polluted, silt-laden waters; many species are suffering a rapid population crash. In a sense, mussels serve as a “canary in the coal mine” for water quality.