Monday, August 13, 2018

Episode 433 (8-13-18): Virginia's Freshwater Mussels - Part 2: Fish Hosts and Mussel Mimicry

CLICK HERE to listen to episode audio (5:40)

This is the second episode in a series on Virginia’s freshwater mussels. Previous episodes in the series are as follows:
Episode 432, 8/6/18 – Part 1: An Introduction to Mussel Biology and Population Status.

Transcript of audio, notes on the audio, images, and additional information follow below.

All Web addresses mentioned were functional as of 8-10-18.


From the Cumberland Gap to the Atlantic Ocean, this is Virginia Water Radio for the week of August 13, 2018.

SOUND – ~ 4 sec

This week, that sound of the North Fork Holston River in Smyth County, Virginia, opens the second episode in a series on Virginia’s freshwater mussels and efforts to restore the populations of these important, filter-feeding components of aquatic environments.  We focus this week on the freshwater mussel life cycle, and particularly the use of a fish host during the larval stage of the cycle.  To begin, have a listen for about 30 seconds to these mystery sounds, and see if you can guess what kind of aquatic collecting is occurring.   And here’s a hint: mussel work can be shockingly complicated.

SOUNDS - ~33 sec

If you guessed, fish collection by electrofishing, you might be a fisheries expert!  You heard Virginia Tech researchers collecting fish in the North Fork Holston on June 19, 2018.  The researchers were using a backpack electrofishing device and a seine, a standard method used by scientists to collect fish.  The objective on this day was to collect darters, a group of fish commonly used by freshwater mussels as hosts for the larval stage.  Fish collection is one part of the mussel-growing operations at Virginia Tech’s Freshwater Mollusk Conservation Center.

Use by larvae of fish hosts is a distinguishing feature of freshwater mussels, and it involves complex mimicry by the mussels to attract fish.  For more on that mimicry, have a listen for about two minutes to Jess Jones, the director of Tech’s Mollusk Conservation Center, during a January 2017 talk.  In the segment, you’ll hear the words glochidium and glochidia, which are mussel larvae, and conglutinate, which is a collection of many glochidia.

VOICE - 115 sec

Freshwater mussels follow complicated life cycles in the complicated world of rivers, streams, and lakes.   That, in turn, complicates efforts to grow mussels for restoring natural populations.   Two more episodes in this series will examine the operations used at Virginia Tech to grow freshwater mussels and to release the lab-raised mussels into Virginia rivers.


Virginia Water Radio is produced by the Virginia Water Resources Research Center, part of Virginia Tech’s College of Natural Resources and Environment.  For more Virginia water sounds, music, or information, visit us online at, or call the Water Center at (540) 231-5624.  Thanks to Stewart Scales for his banjo version of Cripple Creek to open and close this episode.  In Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you health, wisdom, and good water.


Thanks to several fish-collection workers from Virginia Tech and the U.S. Fish and Wildlife Service for allowing an audio recording of their work on June 19, 2018.

Click here if you’d like to listen to the full (18 min./43 sec.) presentation on freshwater mussels given by Jess Jones on January 13, 2017, to faculty, staff, and students of Virginia Tech’s College of Natural Resources and Environment.  Thanks to Will Pfiel of that college for making a recording of that talk available to Virginia Water Radio.

Click here if you’d like to hear the full version (1 min./11 sec.) of the “Cripple Creek” arrangement/performance by Stewart Scales that opens and closes this episode.  More information about Mr. Scales and the group New Standard, with which Mr. Scales plays, is available online at


Mussel life cycle. Image from Louis A. Helfrich, Richard J. Neves, and Hilary Chapman, “Sustaining America's Aquatic Biodiversity—Freshwater Mussel Biodiversity and Conservation,” Virginia Cooperative Extension Publication 420-523, May 2009, online at

Site on the North Fork Holston River in Saltville, Va. (Smyth County) of the June 19, 2018, fish collection work heard in this episode.

Jess Jones (left), director of Virginia Tech’s Freshwater Mollusk Conservation Center, examining the settings on a backpack electrofishing device, June 19, 2018.

Darter collected from the North Fork Holston River in Smyth County, Va., June 19, 2018.


Mussels, both those in freshwater and in marine environments, are classified in the phylum of mollusks.  That large taxonomic group also includes snails, clams, oysters, scallops, squid, and other organisms.

The following information on freshwater mussels is from the Virginia Department of Game and Inland Fisheries, “Freshwater Mussels,” online at

“What is a freshwater mussel?
Freshwater mussels are mollusks and are similar to their marine clam and oyster cousins.  They have two shells connected by a hinge-like ligament.  Around the world, mussels live in a variety of freshwater habitats but are most prevalent in stream and rivers.  They vary in their adult sizes from those as small as a thumbnail to others as big as a pie plate.  The wide variety of shapes and colors are reflected in species like purple wartyback, pink heelsplitter, and threeridge.  On the stream bottom, mussels are sometimes only noticeable by two small siphons, which are used to draw and expel water.  When quickly dislodged, a large muscular foot that is used to move amongst the stream bottom can be readily seen.”

“How are mussels distributed?
“The diversity of freshwater mussels in the United States is unmatched.   Of the estimated 1,000 species worldwide, the United States historically contained 304, about one-thrid of the total world’s fauna.  …The lion’s share of this diversity is found in the southeastern drainages of the Ohio, Tennessee, Cumberland, and Mobile rivers.  One of the most diverse drainages, the Tennessee contains 102 species, nearly one-third of the country’s fauna! Virginia becomes part of the equation because the Tennessee River headwaters are within the southwestern region of the state.  Virginia’s portion of the Tennessee River drainage includes the Powell, Clinch, and Forks of the Holston (North, Middle, and South) rivers….”

“How do mussels function in the environment?
Freshwater mussels are an essential component of our rivers and streams.  By their siphoning actions, mussels filter bacteria, algae, and other small particles, which make them one of the few animals that improve water quality.  Mussels also serve as a food source to many species of fish, reptiles, birds, and mammals.  The outer shell of a live mussel is usually covered by aquatic insects, algae, and plants.  Even when dead, the empty shell functions as a nesting site for small fish like madtoms and darters.”

“What are uses people have found for freshwater mussels?
People have a long history of benefiting from mussels. Native Americans used mussels as a ready food source, implements for tools, and as jewelry.  Before the advent of plastics in the 1930’s, most buttons were made from freshwater mussels.  Modern day buttons retain the luster of those found in earlier times.   Today, freshwater mussels are a key ingredient in the pearl industry. Mussels are collected in several areas of the United States and their shells are sold to Asian markets.  Their shells are used to make numerous round beads that are placed in oysters and serve as the nuclei for freshwater pearls.”

“How do mussels reproduce?
The life cycle of the freshwater mussel is one the most complex and interesting in the animal world.  Unlike other animals that can actively search for a mate, the sedentary mussel depends on the river current to reproduce.  The process begins with the male releasing sperm, and the female located downstream drawing it in through her incurrent siphon.  Numbering in the 100’s to hundreds of thousands, the fertilized eggs develop into glochidia within her gills.   Once mature, they are released into the water column to begin the second part of their lives-attaching to the gills, fins, or scales of freshwater fishes.  At this point, the process is further complicated because not only do the glochidia have to find a fish, but it has to be one of a few specific fish species for the life cycle to continue.  If a glochidium attaches to the correct fish species, it encysts into the fish’s tissue and undergoes a short life as a parasite.   Over several weeks, it begins to develop gills, a foot, and other internal structures to become a juvenile mussel.  The now fully transformed, but still microscopic, juvenile will drop off the fish and begin its life on the stream bottom.…”


Florida Fish and Wildlife Conservation Commission, “Electrofishing FAQ,” online at

Freshwater Mollusk Conservation Society, online at

Robbie Harris, “Growing Mussels,” WVTF FM-Roanoke, Va., 1/7/14, 3 min. video with transcript, online at

Louis A. Helfrich, Richard J. Neves, and Hilary Chapman, “Sustaining America's Aquatic Biodiversity—Freshwater Mussel Biodiversity and Conservation,” Virginia Cooperative Extension Publication 420-523, May 2009, online at

Jess W. Jones, “Freshwater Mussels of Virginia (Bivalvia: Unionidae): An Introduction to Their Life History, Status and Conservation,” Virginia Journal of Science, Vol. 66, No. 3, Fall 2015, pp. 309-331; archives available online at

Jess W. Jones, et al., “Clinch River Freshwater Mussels Upstream of Norris Reservoir, Tennessee and Virginia: A Quantitative Assessment from 2004 to 2009,” Journal of the American Water Resources Association, Vol. 40, No. 4, August 2014; journal available online at (subscription required for back issues).

Lake and Wetland Management, “All About Electrofishing,” 1/28/16, online at

U.S. Fish and Wildlife Service/Endangered Species Program, “Protecting Our Waters: The Mussels of Virginia’s Clinch and Powell Rivers,” by Meagan Racey, 12/27/12, online at

U.S. Fish and Wildlife Service/Maryland Fish and Wildlife Conservation Office, “Freshwater Mussels” (2/18/16), online at

U.S. Fish and Wildlife Service/Midwest Region, “Endangered Species/America’s Mussels: Silent Sentinels,” online at

U.S. Fish and Wildlife Service/Natural Resource Damage Assessment and Restoration Program, online at  See particularly “Protecting and Restoring the Powell River Watershed, Virginia,” December 2010 Fact Sheet, online (as PDF) at; and “Restoring the Clinch River Watershed, Tazewell County, Virginia,” November 2010 Fact Sheet, online (as PDF) at

U.S. Fish and Wildlife Service/Northeast Ecological Services, “Giving Mussels a Boost in Tenn.’s Powell River,” 9/26/12, online at   This site includes a 2 min./32 sec. video on a mussel release and discussion by Jess Jones, online at

U.S. Fish and Wildlife Service/Southeast Region, “Southeastern Mussels,” online at This site includes photos and descriptions of several mussel species found in Virginia and the southeastern United States.

Virginia Department of Game and Inland Fisheries, “Aquatic Wildlife Conservation Center,” online at

Virginia Department of Game and Inland Fisheries videos: “Freshwater Mussels,” 7/6/09, 4 min./31 sec., online at (on a release of fish hosts of the James River Spinymussel into the Cowpasture River); “Endangered Mussels Released into the Clinch River, Largest Release in Eastern US,” 9/30/10, 2 min./36 sec., online at (this corresponds to U.S. Fish and Wildlife Service/Endangered Species Program, “Protecting Our Waters: The Mussels of Virginia’s Clinch and Powell Rivers,” by Meagan Racey, 12/27/12, above); and “Stocking Freshwater Mussels in Virginia’s Clinch River,” 10/28/16, 3 min./35 sec., online at

Virginia Department of Game and Inland Fisheries, “Freshwater Mussels,” online at

Virginia Tech College of Natural Resources and Environment, Mussels released into Tennessee’s Powell River, CNRE News, 2/10/17.

Virginia Tech Department of Fish and Wildlife Conservation, Freshwater Mollusk Conservation Center, online at

G. Thomas Watters et al., The Freshwater Mussels of Ohio, The Ohio State University Press, Columbus, 2009.


All Water Radio episodes are listed by category at the Index link above (  See particularly the following subject categories: “Invertebrates Other Than Insects”; and “Rivers, Streams, and Other Surface Water.”

Following are links to some other episodes on the Holston River or other rivers in the Upper Tennessee River watershed.
Episode 420, 5/14/18 – Exploring Virginia’s Tennessee River Tributaries.
Episode 425, 6/18/18 – Introducing the South Fork Holston River.

Following are links to other episodes on mollusks.
Episode 262, 4/20/15 – Freshwater Snails.
Episode 279, 8/24/15 – Oysters, Nitrogen, and the Chesapeake Bay—Part 1.
Episode 280, 9/7/15 – Oysters, Nitrogen, and the Chesapeake Bay—Part 2.


This episode may help with the following Virginia 2010 Science SOLs.

Grades K-6 Scientific Investigation, Reasoning, and Logic Theme
2.1, 3.1, 4.1, 5.1, and 6.1 – All include “Current applications to reinforce science concepts.”

Grades K-6 Earth Resources Theme
4.9 - Va. natural resources, including watersheds, water resources, and organisms.

Grades K-6 Life Processes Theme
K.7 – basic needs and processes of plants and animals.
1.5 - animals’ basic needs and distinguishing characteristics.
2.4 - life cycles.
3.4 - behavioral and physiological adaptations.

Grades K-6 Living Systems Theme
2.5 - living things as part of a system, including habitats.
3.5 - food webs.
3.6 - ecosystems, communities, populations, shared resources.
4.5 - ecosystem interactions and human influences on ecosystem.
5.5 - cell structures and functions, organism classification, and organism traits.
6.7 - natural processes and human interactions that affect watershed systems; Va. watersheds, water bodies, and wetlands; health and safety issues; and water monitoring.

Life Science Course
LS.1 – understanding of scientific reasoning, logic, and the nature of science, including current applications to reinforce science concepts.
LS.4 - organisms’ classification based on features.
LS.8 - community and population interactions, including food webs, niches, symbiotic relationships.

Earth Science Course
ES.8 - influences by geologic processes and the activities of humans on freshwater resources, including identification of groundwater and major watershed systems in Virginia.

Biology Course
BIO.1 – current applications to reinforce science concepts.
BIO.8 - dynamic equilibria and interactions within populations, communities, and ecosystems; including nutrient cycling, succession, effects of natural events and human activities, and analysis of the flora, fauna, and microorganisms of Virginia ecosystems.

Virginia’s SOLs are available from the Virginia Department of Education, online at

Following are links to Water Radio episodes (various topics) designed especially for certain K-12 grade levels.
Episode 250 (1-26-15) – on boiling, for kindergarten through 3rd grade.
Episode 255 (3-2-15) – on density, for 5th and 6th grade.
Episode 282 (9-21-15) – on living vs. non-living, for kindergarten;
Episode 309 (3-28-16) – on temperature regulation in animals, for kindergarten through 12th grade.
Episode 332 (9-12-16) – on dissolved gases, especially dissolved oxygen in aquatic habitats, for 5th grade.
Episode 403 (1-15-18) – on freezing and ice, for kindergarten through 3rd grade.
Episode 404 (1-22-18) – on ice on ponds and lakes, for 4th through 8th grade.
Episode 406 (2-5-18) – on ice on rivers, for middle school.
Episode 407 (2-12-19) – on snow chemistry and physics, for high school.