Matthew Rowe, Peter Dimmick, and Austin Haney counting and organizing freshwater mussels by species.
When I was first assigned to cover a freshwater mussel survey, I wasn’t exactly thrilled. I mean, the SCUBA part was cool, but I wondered WHY of all the cool, furry, and otherwise charismatic species native to Georgia, I should care about a ‘shell in the mud.’ Then I met and interviewed Matthew Rowe, a freshwater invertebrate biologist, along with Peter Dimmick and Austin Haney, two aquatic technicians who blew me out of the boat with their passion for conserving Georgia’s freshwater mussels. By the end of the survey, I was hooked on conglutinate.
It’s true that most species of freshwater mussels live sedentary lives nestled in soft substrate, filter-feeding on microscopic algae and bacteria that flow their way, but then I learned about their impressive evolutionary biology which includes teeth, fish-like lures and master angling skills.
The marine ancestors and relatives of freshwater mussels have planktonic larvae they release into the water column to be carried by the currents. While this strategy works great in the ocean, it’s not nearly as effective in a river or a lake where there isn’t much water displacement. Impressively, freshwater mussels have evolved to combat this in a number of ways.
One species in the Northeast even has teeth on its shell. When a potential host fish falls for the lure trap, the mussel clamps down on the fish and holds it in place while pumping out its glochidia.
Other species release groups of glochidia called conglutinates which resemble insect larvae or a cluster of fish eggs. When the mussel releases the conglutinate, it will move around on the bottom of the water column until a hungry fish swims by to gobble it up.
In Georgia, there is one freshwater mussel species that challenges even our state Bass Slam winners with its master angling skills. It is known as the shinyrayed pocketbook, and it resides in the Flint River Basin. The shinyrayed pocketbook operates a superconglutinate, which is essentially a long strand of mucous with several glochidial packages attached to it. The superconglutinate floats or is fluttered around in the water to attract host fish, and is an extremely successful and impressive lure. I mean, it caught my attention!
If those reproductive adaptations are not enough to convince you freshwater mussels are cool, just know that they play a major role in indicating water quality and stream health in Georgia. If they are settled in an area, it tells biologists that the habitat has adequate oxygen, low contaminant levels, and has remained relatively free from destabilization of the river or lake bottom. That’s good news for mussels, fish, and anglers alike!
