Today our Nature Study class went snorkeling in the Clinch River near Natural Tunnel State Park in Duffield, Virginia, to get up-close-and-personal with freshwater mussels. Rare and endangered species abound in the Appalachian and Smoky Mountains, and the Clinch River alone sustains 48 imperiled and vulnerable animal species — including 29 varieties of rare freshwater mussels. Because of this concentration of rare animals, the Clinch River has been identified as the number one hotspot in the US for imperiled aquatic species.
The Clinch is home to 45 species of freshwater mussels. Appalachian mussels have terrific names like PURPLE WARTYBACK, SHINY PIGTOE, MONKEYFACE, and PEARLYMUSSEL. Although they all look pretty much alike to the untrained eye, their astonishing diversity is one of the Clinch’s main claims to fame. For a bit of perspective, you’d have to explore every stream in Europe and temperate Asia to find as many species!
Mussels live in a variety of aquatic habitats, but all require areas where the running water has a high oxygen content and supplies a rich food source of organic particles. The constant flow of water also removes waste materials that would be toxic to the mussels, so they are important indicators of water quality. The best substrate (stream bed) for freshwater mussels is a combination of silt, sand, gravel or cobble with little sedimentation.
Adult mussels are sedentary, moving no more than a few feet along the bottoms of the rivers during their entire lifetime, and spending their time flushing water through their bodies and extracting microscopic organisms to eat. The young, however, experience a more adventurous beginning. Each species of mussel has a different species of host fish which it uses as its “nursery.” Female mussels trick fish into coming close by showing off fleshy appendages that act as bait. When a fish swoops close to eat the “bait” the mussel shoots her babies out into the water and they dash to latch onto the fish’s gills where they’ll spend the rest of their early childhood. After several weeks their small shells are formed and they drop off the host fish into the water and float down to the bottom of the stream where they will spend the rest of their lives.
Before the class donned goggles and snorkels, I suggested some things they might look for underwater:
- They could assess the turbidity (cloudiness) of the water by checking its color. If the water appeared green or brown, why might that be? It could indicate the presence of algae or sediment. Why might these be present? An algae bloom brought on by favorable weather/water conditions might account for an excessive tint, while sediment could be caused by recent rains, erosion, or even watercraft activity upstream.
- They could observe the substrate (bottom of the stream). Were there rocks? Were they clean? Are they covered with silt or sand (upstream disturbance or erosion), slime (algae), or a mixture of both? Were there any plants growing in the water? If so, what kind?
After exploring the underwater habitat, we gathered to share observations and record these in our nature journals. I’ll share some of those entries with you soon, and hopefully some of my students (or their moms) will share comments and photos as well.
Life Cycle of a Mussel (short) https://www.youtube.com/watch?v=UD8sHa84M_Q
Mussels Luring Host Fish (mentions evolution) https://www.youtube.com/watch?v=I0YTBj0WHkU
“Planting” Mussels in the Clinch River https://www.youtube.com/watch?v=Uf0ZIoNnuiI
Among the Pond People — Clara D. Pierson (free online) http://www.mainlesson.com/display.php?author=pierson&book=pond&story=_contents
Wild Folk at the Pond — Carroll Lane Fenton
By Pond and River – Arabella Buckley (free online) http://www.mainlesson.com/display.php?author=buckley&book=pond&story=life
Pets from the Pond — Margaret Waring Buck
In Ponds and Streams — Margaret Waring Buck
One Small Square: Pond
Pond and Stream – Arthur Ransome (free online) http://www.gutenberg.org/files/40447/40447-h/40447-h.htm
DK Eyewitness Books: Pond and River
Pond Life (Golden Guides)
http://www.fws.gov/midwest/mussel/harvest.html (button industry)