BIOLOGICAL DISCOVERIES IN THE CLINCH AND POWELL RIVERS AND THEIR IMPORTANCE TO FRESHWATER MUSSEL CONSERVATION Jess W. Jones U.S. Fish and Wildlife Service Department of Fisheries and Wildlife Sciences, Virginia Tech, Blacksburg Powell River, Buchanan Ford, Tennessee
Biological Discoveries in the Clinch and Powell Rivers and Their Importance to Freshwater Mussel Conservation. Jess W. Jones, FWS The mussels, snails, fishes, crayfishes and aquatic insects of the Clinch and Powell rivers are recognized as one of the most biologically diverse freshwater faunas in the world, especially at temperate latitudes. The fauna contains 18 federally endangered mussels and 5 federally endangered or threatened fish, the highest concentration of aquatic listed species in the country. While the mussel fauna has been studied intermittently over the past 30 years, recent field and laboratory investigations highlight several important discoveries: (1) the functional role of mussels in river ecosystems and their reproductive life cycle is more complex than originally thought, with the juvenile stage being especially vulnerable to various commonly occurring contaminants, (2) endangered mussels in each river are less abundant and more geographically confined than previously thought, and in most cases, these are either the last remaining or best population of the species, and (3) patterns of population decline, stability and increase now show that mussel abundance is high and increasing only in the Tennessee section of the Clinch River, whereas mussel abundance is low and declining in large sections of the Clinch River in Virginia and throughout the entire Powell River. For example, current monitoring data indicate that mussel populations have declined precipitously in a ~50 mile section of the Clinch River from St. Paul downstream to Speers Ferry. Ongoing efforts to protect riparian habitat, restore abandoned mine lands, control pollution, and identify sources of contaminants are being implemented to improve the water and habitat conditions of these two rivers. A large collaborative effort is urgently needed to protect and restore these rivers for future generations.
Biological Discoveries & Their Importance to Conservation Functional role of mussels in river ecosystems Mussel life cycle juvenile stage Population trends Importance to conservation Clinch River, Wallen Bend, Tennessee Photo by Jack Looney
Mollusks include both snails and mussels which are a significant component of the fauna in rivers like the Clinch River Photo by Jack Looney
Role of Freshwater Mussels in River Ecosystems Energy transfer filter feeding Nutrient cycling filter feeding Bio-deposition excretion of waste Ecosystem engineering modifications to stream bottom habitat Bioturbation burrowing, reworking the stream bottom sediments Mussels provide multiple ecosystem services Mussel siphoning & filtering water
Carbo, VA Big Stone Gap, VA Cleveland Islands Freshwater mussel monitoring sites in the Clinch and Powell rivers, TN & VA Mussel monitoring sites, lower Clinch River, TN
Brooks Island-Frost Ford Little E Little E Frost Ford Frost Ford Shoal Complex
Brooks Island-Frost Ford Endangered mussels: Dromedary pearly mussel >20,000 Cracking pearlymussel >8,000 Fanshell >3,000 Cumberland combshell >10,000 Oyster mussel >800,000 Endangered fish: Pygmy madtom Slender chub Slender chub Pygmy madtom
Mussel Filtration Rates - Clinch River 1 mussel can filter ~0.5 gallon/hr. 1 mussel = 12 gallons/day Brooks-Frost Ford > 1 million mussels Water filtered/day = 12,000,000 gallons In summer, the river volume can be filtered in a couple river miles
MUSSEL LIFE HISTORY THE OLD PARADIGM Mussels spawn throughout the spring and summer The larvae (glochidia) are obligate parasites on fish Larvae require 2-3 weeks to metamorphose to the juvenile stage
Mussel Fish Hosts
Oyster Mussel Epioblasma capsaeformis Clinch River
MICROLURES
Oyster Mussel Goes Fishing! Captured fish host Releasing fish host infested with larvae
MUSSEL GLOCHIDIA
GLOCHIDIA ATTACHED TO GILL LAMELLAE
250 m NEWLY METAMORPHOSED JUVENILES
Ammonia Toxicity (mgnh 3 -N/L) Species Mean LC50 Citation Glochidia Rainbow mussel (24-h) 0.284 Goudreau et al. 1993 Rainbow mussel (96-h) 0.110 Cherry et al. 2005 Juveniles Pocketbook (96-h) 0.127-0.165 Newton et al. 2003 Wavy-rayed (96-h) 0.26 Mummert et al. 2003 Rainbow mussel (96-h) 0.12 Mummert et al. 2003 Rainbow mussel (96-h) 0.38 Cherry et al. 2005 Toxicity at <0.5 mg/l for juvenile life stages of native mussels
Recent Ammonia Levels (Johnson et al. 2007) Location IW NH3-N(mg/L) Clinch River Ft. Blackmore 0.37-0.68 Indian Creek 1.60-2.06 Powell River Jonesville 1.14
Environmental Stressors and Mussel Declines SEDIMENTATION AGRICULTURE MINING TOXIC SPILLS
Carbo, VA Big Stone Gap, VA Cleveland Islands Freshwater mussel Mussel monitoring monitoring sites sites, in the middle Clinch Clinch and Powell River, rivers, VA TN & VA
Middle Clinch River Longterm Trend Monitoring, 1979-2009 Sites & River Mile (RM) Speers Ferry, VA (211.1) Pendleton Island, VA (226.7) Simones Island, VA (235.1) Quantitative sampling for mussels
Middle Clinch River, VA 1979-2009 30 Mussels per m 2 25 20 15 10 5 P < 0.01 0 1975 1980 1985 1990 1995 2000 2005 2010 At investigated sites, total mussel abundance has decreased by 80%.
Pendleton Island Mussel Preserve, VA (RM 226.7) Historically, best site on Clinch River Discovered in 1977-1978 by TVA biologists Purchased by TNC in 1983 43 species documented Populations now in severe decline
Right Descending Channel
Left Descending Channel
Pendleton Island, VA 1979-2009 30 Mussels per m 2 25 20 15 10 5 P < 0.001 0 1975 1980 1985 1990 1995 2000 2005 2010 2015 Total mussel abundance has declined by 96%.
Pendleton Island: Lost Ecosystem Services Available Habitat: Left Channel = 16,000 m 2 Right Channel = 16,000 m 2 Other Areas = 8,000 m 2 Total Habitat = 40,000 m 2 Historical Mussel Abundance: 25 m 2 of mussels 40,000 m 2 of habitat Total = 1 million mussels Filtration Services Lost: 1 mussel can filter 12 gallons per day Historically, 12 million gallons filtered per day Today, 480,000 gallons filtered per day 96% decline of site capacity
Middle Clinch River, VA Guest River St. Paul, VA RM 252 Pendleton Island RM 226 Clinchport RM 213
Mussel Distribution and Abundance Range contractions for endangered mussels in both rivers Last or best remaining populations of most endangered mussels Declines in mussel abundance: - Virginia section of Clinch River - Throughout entire Powell River Endangered monkeyface mussels, Powell River
MUSSEL PROPAGATION FACILITIES Two mussel hatchery facilities in Virginia Both focus on restoring mussel populations in the Clinch and Powell Rivers Aquatic Wildlife Conservation Center, VDGIF, Marion Freshwater Mollusk Conservation Center, Virginia Tech, Blacksburg
MUSSEL PROPAGATION & RESTORATION
Restoration of Mussel Populations Tagged adult mussels Releasing adult mussels
Biological Discoveries and Their Importance to Conservation in the Clinch and Powell Rivers Due to their complex life cycle, especially the juvenile stage, improving water quality and habitat conditions is critical to the survival of freshwater mussels Mussels play important roles in river ecosystems that benefit wildlife and humans Survival of more than a dozen mussel species is now dependent on remaining populations in the Clinch and Powell Rivers Conservation efforts must continue to focus on reducing and eliminating sources of pollution
Questions Spiny river snail tending an egg clutch in the Clinch River