ecology and conservation of freshwater mussels in north america · 2014-09-29 · ecology and...

Ecology and conservation of freshwater mussels

in North America

Wendell R. Haag

US Forest Service

Southern Research Station

Part I. Mussel ecology

Background: Diversity

• Over 300 species

Diversity


• Highest diversity concentrated in southeastern US

Diversity



• High alpha diversity:

Tennessee River, Muscle Shoals, AL ~ 70 species

Ohio River, Campbell Co., KY ~ 63 species

Green River, Hart Co., KY ~ 51 species

Diversity



• High alpha diversity

• High micro-scale diversity: up to 23 species/m2

Background: other noteworthy facts

• Filter feeders; provide vital ecosystem services

• Critically imperiled:

• ~30 species already extinct

• 80 species federally endangered

• additional 45 species considered imperiled

• Overall, 50% of fauna extinct or imperiled

“Why do you want to study

mussels? They don’t do anything.”

Courtesy Jacqueline Madill

Mussel life cycle

Host generalists

Host specialists: lures for top predators

Host specialists: lures for invertivore fishes

Host capture

Mussel age and growth

Life span: <5 to >100 years Growth rate: K from ~ 0.01 – 1.0 Age at maturity: <6 months – 10 years

Fecundity Species Mean annual fecundity

Pegias fabula <500

Quadrula asperata 8,308

Fusconaia cerina 23,922

Pleurobema decisum 33,975

Obliquaria reflexa 48,618

Villosa iris 57,667

Ellipsaria lineolata 97,833

Elliptio arca 130,114

Lampsilis ornata 281,709

Amblema plicata 325,087

Pyganodon grandis 412,300

Ligumia recta 1,076,833

Leptodea fragilis 11,873,663

Annual recruitment

Obovaria unicolor

0

10

20

30

40

50

60

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

Quadrula asperata

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

Benevola Island

Deerfly Bar

Pleurobema decisum

Fusconaia cerina

Medionidus

acutissimus

0

10

20

30

40

50

60

Elliptio arca

0

10

20

30

40

50

60

Year

Re

cru

itm

en

t (p

erc

en

t o

f to

tal p

op

ula

tio

n)

Mean (c.v.%) = 2.6 (77.5)

15.5 (81.5) 6.9 (57.2)

25.7 (85.0)7.9 (67.1)

14.7 (124.4)

Recruitment and streamflow

Medionidus acutissimus

0

10

20

30

40

50

60

70

Benevola Island

Deerfly Bar

Pleurobema decisum

0

5

10

15

20

0 200 400 600 800 1000

Recru

itm

ent

(%)

Mean August streamflow (cfs)

Ahet

Alig

Amar

Apli

Apli-LT

Apli-SR

Avir

Cmon

Cste Ddro

Earc

Ecap

Ecra

Elin

Fcer

Halt

Lfra

Lorn Lrec

Lrim

Lstr

Lsub

Lter

Macu

Mmar

Mner

Oref Ouni

Pcol Pdom

Pfas Pdec

Pgra

Pohi

Ppur

Qasp

Qpus

Qrum

Ssub

Tdon

Tpar

Ttex

Ttru

Uimb

Vell

Vlie

Vneb

-1,8

-1,3

-0,8

-0,3

0,2

0,7

1,2

1,7

-1,2 -0,7 -0,2 0,3 0,8

Axi

s 2

(7

2%

)

Axis 1 (24%)

Opportunistic strategy

Periodic strategy

Fecundity Body size

High Low

High

Low

Age

at

mat

uri

ty

Life

sp

an

Equilibrium

strategy

darter

minnow

bass

catfish

sturgeon

drum

skipjack

Small streams

basscatfish

Per.

drum

skipjackminnow

Isolated lentic habitatshigh disturbance

Lentic microhabitatshigh disturbance

Mid-sized streams

Large streammussel beds

Per.

Per.

Opp.

Opp.

Opp.

Eq.

Per.

Per.

catfishdrum

darter

darter

darter

minnow

minnow

minnow

bass

bass

catfish

catfish Eq.

Opp.

minnow

darter

drum

sturgeon

Part II. Mussel declines and conservation

First extinction wave: 1930-1980

Cumberland River system Kentucky and Tennessee Historical = 89 species

Present = 42 species

Extinctions from dams: at least 30

opportunistic

Entire North American

fauna

First extinction

wave

equilibrium

periodic

Second extinction wave: 1970s - present

• Rapid mussel declines in unimpounded

streams with few obvious impacts

Little reproduction in most affected populations

0

5

10

15

0 20 40 60 80 100

0

0.5

1

1.5

2

2 18 34 50 66

Freq

uen

cy

“healthy “ population declining population

Length (or age)

Second extinction wave: 1970s - present

• Rapid mussel declines in unimpounded

streams with few obvious impacts

Result:

• About 40 species now critically endangered

• Another ~80 imperiled to some extent

opportunistic

Entire North American

fauna

First extinction

wave

Second extinction

wave

equilibrium

periodic

Pond experiments at Auburn University

Experiment 1: Efficiency of sperm dispersal and egg fertilization

Ho: fertilization should decrease with distance between males and females

Experimental design

Distance from Males (m)

Pro

po

rtio

n o

f g

ravid

fe

ma

les

0.0

0.2

0.4

0.6

0.8

1.0

1 10 25

Flow

No Flow


0 5 10 15 20 25 30

Ferti

lizat

ion

Effi

cien

cy

0.0

0.2

0.4

0.6

0.8

1.0

1.2Flow

No Flow

% o

f eg

gs f

erti

lized

/fem

ale


-5 0 5 10 15 20 25 30

Mea

n nu

mbe

r of

glo

chid

ia p

er m

usse

l

0

50000

100000

150000

200000

250000

300000Flow

No Flow

Nu

mb

er o

f gl

och

idia

pro

du

ced

/fem

ale

Spermatozeugmata: “Sperm balls”

Experiment 2: Role of host fish abundance in mussel recruitment

0

500

1000

1500

0 500 1000 1500 2000 M

uss

el r

ecru

itm

ent

Host abundance

H1: recruitment should increase with increasing host abundance

H2: mussel species with shared hosts should compete for hosts

H3: recruitment rate should be influenced by host infection strategy

Pondmussel (Ligumia subrostrata)

Host specialist

sunfishes (Lepomis, Micropterus)

Mantle lure

Giant floater (Pyganodon grandis)

Host generalist

Broadcast mucus webs

Bluegill (Lepomis macrochirus)

Rec

ruit

men

t

Host fish abundance

Host fish abundance

Mussel declines

Upcoming work (to begin fall, 2014)

In situ survival of juvenile mussels in streams and correlations with water and sediment quality factors With collaborators from Kentucky Department of Fish and Wildlife Resources, Daniel Boone National Forest, Kentucky Division of Water, US Fish and Wildlife Service, Auburn University, University of Georgia, North Carolina State University

silos Sediment cages

Contaminant analysis

General factors

Current use pesticides

Legacy pesticides

Ammonia, nitrate, nitrite Atrazine DDT/DDE

Phosphorous Glyphosate Chlordane

Conductivity 2,4-D Hexachlorobenzene

pH Simazine Toxophene

Dissolved oxygen Metolachlor Aldrin

Chloride Prometon Methoxychlor

Sulfate Acetochlor PCB

Suspended solids Diazinon Heptachlor

Volatile organics? Carbaryl Dieldrin

Substrate embeddedness? Alachlor

Mercury Methyl Bromide

Manganese

Other metals?

Selenium

silos Sediment cages

About 25 sites in Kentucky

Thanks! Merci beaucoup!

Culprits?

Timeline of enigmatic declines: late 1960s to present

• 1940-50s: wide use of organochlorine pesticides (e.g., DDT) • 1958: Atrazine registered • 1974: Roundup developed • 1970s: no-till agricultural methods • Proliferation of synthetic nitrogenous fertilizers

The usual suspects: sediment, dams, overharvest, pollution

ecology and conservation of freshwater mussels in north america · 2014-09-29 · ecology and...

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