U.S. Fish & Wildlife Service

Endangered and Threatened Mussels in the

Apalachicola-Chattahoochee-Flint Basin

Freshwater Mussel Facts

Common and scientific names:

Fat threeridge mussel (Amblema

neislerii), Shinyrayed pocketbook

(Lampsilis subangulata), Gulf

moccasinshell (Medionidus penicillatus),

Oval pigtoe (Pleurobema pyriforme),

Chipola slabshell (Elliptio chipolaensis),

and Purple bankclimber (Elliptoideus

sloatianus).

Status: All six mussels were listed on

March 16, 1998.

Description: Mussels are bivalve

mollusks, which means they have two

valves (shells) surrounding a soft fleshy

body. Freshwater mussels are related to

snails, oysters, clams and squids.

Habitat: Mussels live in the sand and

gravel bottoms of streams and rivers.

They require good water quality, stable

stream channels and flowing water.

Diet: Mussels filter their food out of the

water. They eat algae, other small plants

and animals and possibly bacteria that

grow on pieces of plant debris.

Life history: The larvae of these mussels

are parasites on the gills and fins of

freshwater fishes, including darters,

minnows and bass. The larvae use the

host fish for dispersal and cause them

little to no harm. Many mussels use

lures that mimic minnows, worms,

leeches or aquatic insects to attract a

suitable fish host.

Natural predators: Some species of

fishes and turtles, as well as muskrats,

raccoons, and otters feed on mussels.

Threats to survival: Habitat modification

through manmade structures like dams

and channel alterations has destroyed

free-flowing water habitats. These

modifications restrict mussels and fish

from dispersing which results in small,

isolated populations. In addition to

habitat modifications, mussel

populations are exposed to point source

pollution and nonpoint source pollution

such as toxic runoff containing

fertilizers, herbicides and pesticides

from land-use

practices.

Purple bankclimber

Shinyrayed pocketbook

Gulf moccasinshell

Oval pigtoe

Fat threeridge

They make no sound. They

cannot see. Some may live for

decades, but seldom move from

a secure spot. Yet, freshwater

mussels are causing a stir;

becoming noticed and making

us ponder their future as we

make plans for our own.

Mussels are in trouble. No other country in

the world equals the United States in

freshwater mussel variety. While all of

Europe supports only 12 species, nearly 300

kinds live here. It’s estimated that 70% of

our freshwater mussels are extinct,

endangered, or in need of special protection.

In the Apalachicolan Region, three species

have already been declared extinct, seven

have been federally protected under the

Endangered Species Act, and six more are

proposed as candidates for federal

protection. Many of their problems stem

from how they live and changes that have

occurred to their habitat during the past 200

years.

Why are freshwater mussels so

imperiled?

Our native freshwater mussels face greater

problems today than they did just a few

years ago. Some problems aren’t new.

Although water quality has improved in

some areas, pollution, especially non-point

source pollution, causes the greatest threat

to native mussels. Also sedimentation

continues to take a serious toll. Habitat

losses through channelization, clearing of

riparian and streambank vegetation,

dredging, and dam construction still persist.

Mussels are impacted by loss of fish hosts

from fish kills or dams that prevent fish

migration. Poachers can impact mussels by

violating harvest regulations set by

conservation agencies. However, in some

parts of the country, it’s a non-native mussel

causing the most concern.

Chipola slabshell
U.S. Fish & Wildlife Service

Life Down Under

Most freshwater mussels live

burrowed in sand and gravel at the

bottom of rivers and streams. Only a

few are adapted to the quiet water

and muddy depths of lakes, ponds,

and reservoirs.

Unlike most animals, which must

travel in search of food, their food

drifts to them, mainly tiny plants and

animals called plankton suspended in

the water. By drawing water inside

their shells through a siphon, their

gills filter out food and take in

oxygen.

Mussels usually don’t move much, but

a muscular “foot” helps them burrow

and allows limited travel if disturbed

by floods or drought. The foot also

helps anchor them against strong

currents and may prevent a hungry

muskrat from tugging them out for

its dinner! A mussel’s shell, however,

provides its main protection from

predators.

Their hard, calcium-based shells

consist of two halves joined by a

hinge. Unique names like “fat

threeridge,” “purple bankclimber,”

and “Chipola slabshell” refer to the

wide range of shell size, color, shape,

and texture found among mussel

shells.

Although their lives appear boring,

their reproductive strategies are

quite fascinating. Fertilized eggs

develop and are released into the

water to begin a parasitic stage. With

little time to waste, these youngsters,

called glochidia, must attach

themselves to a host fish or perish.

For some mussels, the host is limited

to only a few fish species. This

harmless parasitic stage lasts a

matter of weeks before the larvae

transform into young mussels and are

ready to drop off the fish and begin a

life in the stream bottom.

Why do we care?

■ Monitors of aquatic health:

the presence of diverse and

reproducing populations of mussels

indicate a healthy aquatic system

which means good fishing, good

water quality for waterfowl and

other wildlife species, as well as

insurance that our water is safe.

Conversely, when mussel

populations are at risk, it indicates

problems for other fish and wildlife

species, and people too.

■ Ecological value:

mussels are natural filters, feeding

on algae, plankton, and silts, they

help purify the aquatic system.

Mussels are also an important food

source for many species of wildlife

including otters, raccoon, muskrat,

herons, egrets, and some fish.

■ Economic value:

freshwater mussels have been and

continue to be a major economic

resource; first in the button

industry and now in the cultured

pearl industry. Mussels from North

American form the nucleus of the

cultured pearl industry in Asia.

■ Education and aesthetic value:

the study of mussels, their natural

history, and habitat requirements

provides interesting and important

lessons on the interconnectedness

of the aquatic system and how

species adapt to their ecosystem.

■ Cultural value:

Mussels played an important role in

the cultural history of prehistoric

and recent native peoples of the

Apalachicola River Basin. They

were used as food and the shells

were used for ornamentation, tools,

and as a commodity for trade.

Indian shell middens (the piles of

shells that native Americans have

left behind) extend for miles along

sites of old villages and encampments

along the Apalachicola River.

■ Biodiversity:

Mussels have, and hopefully will

continue, to play an important role in

our aquatic ecosystems. Considering

that less than 20 mussel species are

found in most other countries of the

world, our North American rivers

and streams are truly “rich” with

close to 300 species!!

Some mussels do not get cancer.

Researchers want to know why and

mussels may have additional values

in the future that we cannot now

predict. The loss of any of these

species will definitely have

consequences on how the aquatic

ecosystem functions.

What is being done?

Biologists from the U.S. Fish and

Wildlife Service (Service) and the

U.S. Geological Survey along with

other Federal, State, and private

agencies are working together to find

solutions to problems facing our

mussels.

The Endangered Species Act of 1973

provides an important tool for

conservation of endangered and

threatened species. Federally

endangered species are so rare they

are in danger of becoming extinct.

Unfortunately, extinction is forever

and once gone, a species can never

return to our web of life. Threatened

species are more abundant at this

time but may become endangered in

the future.

How can you help?

In order to protect mussels, thereby

protecting ourselves, the following

things can be done:

■ Limit or cease pesticide use to

conserve soil and prevent runoff

into nearby lakes and streams.

Integrated Pest Management

(IPM) strategies can replace

pesticide use—find out more about

it.

■ Help control soil erosion by

planting trees and plants to avoid

runoff of soil into freshwater areas.

■ Remove aquatic weeds from boat

trailers and motors before using

again to prevent the spread of

things such as zebra mussels. Do

not throw weeds back into the

water.

■ Help support watershed

management programs by calling

your local resource management

agency.

■ Support and follow zebra mussel

quarantine, inspection, and

decontamination programs.

■ Conserve water.

For more information, contact:

Panama City, Florida Field Office

850/769 0552

or

Athens, Georgia Field Office

706/613 9493

or

Tom MacKenzie, Media Relations

External Affairs, Atlanta

404/679 7291