By Cameron Baxley
November 30, 2023–This past October, Spiders Slough was completely disconnected from the Apalachicola River for about a month. Large stretches looked like well-maintained hiking trails rather than a creek. Fall is typically when the Apalachicola experiences less flow. Lower flows are essential for some biological processes. However, too little water flow for too long does have a negative impact. It is the timing, the duration and the quantity of flow that work together to create the diversity the Apalachicola River.
Some of the animals that inhabit the floodplain have limited mobility. They can get trapped and even perish. Mussels are one such river inhabitant that is at risk. They are the most imperiled group of animals in the United States. In November, Apalachicola Riverkeeper enlisted a team comprised of staff and volunteers to 1) collect any deceased mussels and 2) relocate any at-risk mussels to better habitat. The collected mussels will be sent to mussel researcher Dr. Michael Gangloff, a researcher on our Slough Restoration Project team.
Dr. Gangloff writes, “Mussels can provide us with an indicator of both how much connectivity sloughs have, as well with main stem river habitats. Sloughs with high connectivity tend to have more species as well as more sensitive mussels (including Fat threeridge and Purple bankclimbers). By examining the size class distribution (and age structure) of the mussels (or dead shells), we can get some info about how long the slough has been wet and, by extension, the last time it was connected to the river. Mussels can also tell us a bit about what fishes may be using the sloughs. For example, if we find purple bankclimber shells in restored sloughs, then we could infer that sturgeon are likely using those systems. However, we have not yet found purple bankclimbers in either Spiders or Douglas sloughs.”
He continued, “Based on the existing data, the biggest issue facing Fat threeridge in the Apalachicola was dredging. However you can’t say that it was the main factor affecting other taxa. There are 20+ species in the river, including at least three other listed species, so it’s not a one size fits all problem. Anything that is a slough specialist is certainly affected by low flow. However, low flows are probably good for reproduction/recruitment of all mainstem species because fish are concentrated and juveniles are more likely to settle in good habitat (as opposed to the floodplain). The only way to know is to keep monitoring and don’t let the dredging start again.”
Many thanks for our volunteer mussel crew, Cameron Barton, Lynn Wamp, Chris Watkins who didn’t hesitate to slip around in the mud to hunt for dead mussels.
Dr. Michael Gangloff is Freshwater Conservation Biologist at Appalachian State University.
Cameron Baxley is Riverkeeper at Apalachicola Riverkeeper. She can be reached at [email protected]