Freshwater mussels of Georgia

I used to think clams were boring, but that was before I learned about their reproductive life cycle.  I formerly thought of bivalves as inactive organisms that live on aquatic bottoms like a dead stick in the mud.  It’s true most species of freshwater mussels are sedentary life forms, filter-feeding on the microscopic algae and bacteria that are carried their way by currents.  The males and females are even incapable of approaching each other to mate.  Instead, the male ejects sperm into the water and the female takes it in while filter feeding, thus fertilizing her eggs.  Amazingly, the female tricks more advanced creatures into helping spread her larva.  Some species of mussels have a fleshy protuberance that resembles a worm or small minnow.  When a fish strikes at the bait, the female mussel squirts her larva onto the fish’s gills.  Eventually, the larva develop into little mussels and drop to the bottom of a river or lake and burrow into the mud where they’ll probably live for the rest of their lives.  Other species of mussels release bags that resemble myriads of tiny aquatic insects.  A fish striking the bag releases hundreds of larva which attach themselves to the fish’s gills.  Biology majors seeking a subject for a master’s thesis take note–little is known about which mussel species parasitize which fish species, so the field of study is wide open.

Life cycle of a freshwater mussel.

Elliptio complanata–Eastern elliptio.  This widespread freshwater mussel occurs in almost every river system in Georgia.  It’s quite edible.  I’ve never eaten one, but I picked up a dead one not long ago and the inside looked and smelled just like an oyster.  It left a carrion-like odor on my hand, however, indicating it had gone rotten.

The Altamaha Spinymussel–Elliptio spinosa.  This endangered species only inhabits the Altamaha River.

Top: Anodonta grandis–Giant Floater…Bottom: Villosa dumbelis–Eastern Creekshell

Rayed Pink Fatmucket–Lampsilis splendida

Anodonta imbecilis–Paper pondshell

A great variety of mussel species live in Georgia’s waters–the exact number is probably unknown.  There’s an estimated >126 species from at least 16 genera, though many are in danger or have succombed to extinction.  Mussels live a long time–up to 100 years.  Nevertheless, many species are endangered.  Dams, sedimentation, pollution, and the introduction of invasive Asiatic clams and zebra mussels have all reduced the amount of available habitat.  Before Europeans colonized North America mussels were an abundant food source for the Indians.  Georgia’ s rivers used to be crystal clear for most of the year, except during summer when Indians burned the woods, and they became black with ash (a practice they engaged in every year).  Today, Georgia’s rivers are clogged with agriculturally eroded mud.  This is not good for filter-feeders.

Surprisingly, I found no information about Pleistocene-aged freshwater mussels in Georgia on the web.  Mussel shells are as durable as bone and should be present in alluvial fossil sites.  I suspect they’ve been ignored or unnoted because scientists don’t know whether specimens associated with alluvial fossil bones are from the present or the Pleistocene.  Leisey Shell Pit in Florida is a famous fossil site noted for bivalve shells, but these are sea shells, dating to when the site was under ocean water.  Nevertheless, freshwater mussels were certainly abundant in Pleistocene freshwater environments throughout the south.  Most were probably the same species that today are heading for extinction.

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5 Responses to “Freshwater mussels of Georgia”

  1. jamesrobertsmith Says:

    Freshwater mussels are indeed in trouble here in the South. At least the native species are. I see a lot of mussel shells in my hikes along some waterways…signs of predation by raccoons, minks, and otters. I’ve never eaten freshwater mussels, but I’ve heard they’re okay.

    Having lived on the coast of Georgia for much of my life, I grew up harvesting and eating oysters. What I didn’t know until I was almost 20 years old was how common clams were on the Georgia coast. Easy to harvest, too, if you don’t mind shoving your hands into sandy banks in the marsh and hoping you don’t encounter a stingray. I once filled a 14-foot johnboat with clams a friend and I gathered in just a small section of a marsh channel on Jekyll Island.

  2. markgelbart Says:

    Euell Gibbons wrote a book devoted to gathering clams and other sea shore creatures.

    He was a delightful writer, if you ever get a chance to read one of his books. Used copies can be had for next to nothing.

  3. jamesrobertsmith Says:

    I remember him. He was quite popular when I was a kid. My parents sold quite a number of his books in their shops. STALKING THE WILD ASPARAGUS was one that I recall.

    One thing that I do miss about living on the coast is the availability of plenty of free protein. I could go out with a bucket and harvest all of the oysters I could possibly eat–and pay not a dime for it. Or I could wade out in the breakers with my cast net and it was a question of how much fish I could carry away from the beach, not whether or not I’d catch anything.

  4. markgelbart Says:

    I used to fish for mullet using a cast net. A perfect cast into a school of those fish caught enough for the whole family.

  5. jamesrobertsmith Says:

    Yep! In my youth my favorite place to catch mullet was a man-made inlet on Jekyll Island. The fishing there was fantastic with a cast net. Last time I was there, though, the State had apparently stopped dredging it and it had largely filled in and was mainly just a flat plain of broken oyster shells now mostly above the high tide line.

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