biological discoveries in the clinch and powell rivers - Virginia Water ...

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

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