Sometimes a disaster delivers hope in surprising packages. When Tropical Storm Helene arrived, the Swannanoa Valley was severely affected because its steep slopes are drained by many streams which join to form the Swannanoa River. Amid streambanks stripped to bare soil and with a human disaster response underway, the muddy water slowly began to clear—and a special little fish was discovered by biologist Patrick Ciccotto and his students at Warren Wilson College: the Swannanoa darter (Etheostoma swannanoa).
The team was thrilled, as this 2-3” fish may be small, but it implies hope for the restoration of the entire biota in the Swannanoa. So what makes something so small be such good news for a beleagured waterway?
Darters are fairly common in cold, clear riffles with a clean, rocky bed. These small, boldly striped and often colorful fish spend much of their time among the rocks on the bottom, perching like tiny birds against the push of the current using their stout pectoral fins like tiny anchors. These little omnivores have good vision, and they dine on snails, fish eggs, small crustaceans, aquatic insects and more. When spotting a food item, they dart forward like tiny missiles to strike their intended meal, then return to a rocky perch. Their behavior is so distinctive, it gives this group of at least 120 species their name – darters.
Like all darters, the Swannanoa darter is negatively impacted by high levels of sediment and other pollutants. Too much sediment—soil particles arriving from the landscape—covers the rocky bottom, clogging or damaging their gills, and makes it difficult to see and catch their food. As excess sediment settles on the streambed, it fills the small spaces between rocks—spaces that are critical for shelter from predators and spawning sites for reproduction. Additionally, their preferred diet includes larval mayflies and caddisflies, which are sensitive to the same pollutants and cannot survive in streams with excess sediment.
As the name suggests, the Swannanoa darter is primarily found in the Swannanoa River; E. swannanoa is found only sporadically in other Tennessee River headwaters like the Clinch, Holston, Watauga, and Nolichucky. What’s more, Helene arrived after many darters had spawned, and their tiny young were doing their best to avoid becoming food and surviving to reproduce this year. Dr. Ciccotto’s observation of the native Swannanoa darter is a promising sign that—despite spikes in sediment inputs, increased pollution, and major physical changes to the stream bed due to catastrophic flooding—freshwater ecological systems are still functioning well enough to support some of the wildlife that has evolved in this ancient valley. These early results also show that several other native fish species—such as central stonerollers, Tennessee shiners, longnose dace, and greenside darters—still inhabit the Swannanoa River. It’s exciting to know they persist, both for the important ecological roles they play and the biological insight they provide. For example, river chubs (Nocomis micropogon) are another species that require clean mountain streams to thrive.
River chubs are opportunistic feeders—eating just about anything they can find—but they also serve as prey for larger fish. During spawning season, males build and defend pebble mounds on the stream bottom, where females may lay their eggs. Other fish, like darters and minnows, will opportunistically use these mounds for their own spawning. In addition, river chubs play an essential role in the life cycle of freshwater mussels, acting as a host for the mussels’ larval stage. So the presence of river chubs in the Swannanoa River—even after the increased sediment from Hurricane Helene—suggests that the recovering river provides some baseline conditions for other sensitive aquatic animals to survive and reproduce.
While it is exciting to know that our own Swannanoa darter still swims in its native waters—how can we ensure the next generation will be able to snorkel these waters and discover the familiar fish?
Prior to Hurricane Helene, the Swannanoa River was already classified as impaired, due to its reduced ability to support aquatic life owing to excess sediment (soil flowing into the stream) and low numbers of indicator species (sensitive aquatic creatures that reflect water quality). Local organizations including the Environmental Quality Institute (EQI) have been monitoring these impairments before and after Helene, documenting spikes in sediment levels in the Swannanoa River, particularly during the debris removal process when heavy equipment was used in and along the stream.
At RiverLink, we’ve completed many projects to help prevent pollution from entering local waterways. Since Helene, our Adopt-a-Stream program is using volunteers to help replant and repair damaged streambanks; we’ve also partnered with Anchor QEA and Wildlands Engineering to evaluate and plan restoration efforts along 6.6 miles of the Swannanoa. As the Swannanoa River flows through our communities, it has helped shape a strong culture of people who feel connected to it—and who care deeply about its health. As we monitor, advocate for, and work to improve this great stream, it supports us in return — through recreation in connection with nature, and an astonishing diversity of living things, all linked by a network of living waterways.
