Ecology and conservation of freshwater mussels in North America · 2014-09-29 · Ecology and...
Transcript of Ecology and conservation of freshwater mussels in North America · 2014-09-29 · Ecology and...
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Ecology and conservation of freshwater mussels
in North America
Wendell R. Haag
US Forest Service
Southern Research Station
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Part I. Mussel ecology
Background: Diversity
• Over 300 species
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Diversity
• Over 300 species
• Highest diversity concentrated in southeastern US
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Diversity
• Over 300 species
• Highest diversity concentrated in southeastern US
• High alpha diversity:
Tennessee River, Muscle Shoals, AL ~ 70 species
Ohio River, Campbell Co., KY ~ 63 species
Green River, Hart Co., KY ~ 51 species
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Diversity
• Over 300 species
• Highest diversity concentrated in southeastern US
• High alpha diversity
• High micro-scale diversity: up to 23 species/m2
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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
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“Why do you want to study
mussels? They don’t do anything.”
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Courtesy Jacqueline Madill
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Mussel life cycle
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Courtesy Jacqueline Madill
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Host generalists
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Host specialists: lures for top predators
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Host specialists: lures for invertivore fishes
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Host capture
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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
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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
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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)
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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)
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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
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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
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Part II. Mussel declines and conservation
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First extinction wave: 1930-1980
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Cumberland River system Kentucky and Tennessee Historical = 89 species
Present = 42 species
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Extinctions from dams: at least 30
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opportunistic
Entire North American
fauna
First extinction
wave
equilibrium
periodic
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Second extinction wave: 1970s - present
• Rapid mussel declines in unimpounded
streams with few obvious impacts
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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)
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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
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opportunistic
Entire North American
fauna
First extinction
wave
Second extinction
wave
equilibrium
periodic
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Pond experiments at Auburn University
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Courtesy Jacqueline Madill
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Experiment 1: Efficiency of sperm dispersal and egg fertilization
Ho: fertilization should decrease with distance between males and females
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Experimental design
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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
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Distance from Males (m)
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
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Distance from Males (m)
-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
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Spermatozeugmata: “Sperm balls”
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Courtesy Jacqueline Madill
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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
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Pondmussel (Ligumia subrostrata)
Host specialist
sunfishes (Lepomis, Micropterus)
Mantle lure
Giant floater (Pyganodon grandis)
Host generalist
Broadcast mucus webs
Bluegill (Lepomis macrochirus)
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Rec
ruit
men
t
Host fish abundance
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Host fish abundance
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Courtesy Jacqueline Madill
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Mussel declines
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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
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silos Sediment cages
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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
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silos Sediment cages
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About 25 sites in Kentucky
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Thanks! Merci beaucoup!
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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