Seasonal prey shifts and bioenergetics
Daniel D. Magoulick
Arkansas Cooperative Fish and Wildlife Research Unit
Department of Biological Sciences
University of Arkansas - Fayetteville
Zebra Mussel
Dreissena polymorpha
Zebra Mussels on a Native Mussel
Lock Gate with Zebra Mussels
Freshwater Drum
Aplodinotus grunniens
Questions
• What fish species prey on zebra mussels
in Lake Dardanelle and the Arkansas
River?
• Do fish predators prefer zebra mussels
over other prey? Is this affected by fish
size or season?
• Are zebra mussels a profitable prey item
for fishes in Lake Dardanelle?
Potential Predators and Prey
Preference
Illinois Bayou
Spillway
LEGEND
River
Channel
City of
Russelville
Creek
Channel
Predation Experiment
Site
Fish Collection
Site
Dardanelle
Dam
Study Site
N
Zebra Mussels in Blue Catfish
Predator
N
Fish
Size (mm)
Number
Containing
D. polymorpha
Percent
Containing
D. polymorpha
Blue catfish (Up to 6/98) 586 229-686
310
52.90
Blue catfish (7/98-1/99)
257 305-635
1
0.4
Channel catfish
798 76-533
0
0
Freshwater drum (S)
340 76-190
0
0
Freshwater drum (L)
164 191-584
79
48.17
Bluegill
201 127-203
0
0
Redear sunfish
236 51-254
236
100.00
River carpsucker
67
279-508
0
0
Spotted sucker
36
229-432
0
0
Common Carp
19
381-686
0
0
Blue Catfish Prey Selection
Lake Dardanelle 1996-1999
100
100
80
80
60
ZM
60
Shad
40
40
Other
2020
00
Empty
12/97
1/99D J
J7/96
A S9/96*
O N 1/97
D J 3/97
F M 4/97
A M 9/97*
J J A
S O1/98
N D3/98
J F 5/98
M A 6/98
M J 8/98
J A 9/98
S O N
1996
1997
Sample Dates
1998
Gizzard Shad (Dorosoma cepedianum)
Winter Die-Off
Buoy and Sample Plates
Summer 1996
Blue Catfish Prey Selection
Lake Dardanelle 1996-1999
100
100
80
80
60
ZM
60
Shad
40
40
Other
2020
00
Empty
12/97
1/99D J
J7/96
A S9/96*
O N 1/97
D J 3/97
F M 4/97
A M 9/97*
J J A
S O1/98
N D3/98
J F 5/98
M A 6/98
M J 8/98
J A 9/98
S O N
1996
1997
Sample Dates
1998
Zebra Mussel Die-off
Summer 1997 and 1998
Zebra Mussels Consumed by Blue Catfish
Predator Size Classes
(N = 463)
40
30
20
10
0
203.2
254
304.8
355.6
406.4
457.2
508
Blue Catfish Size Classes (mm)
Fish Containing Zebra Mussels
558.8
609.6
660.4
Total Number of Fish/Size Class
>711.2
Length of Zebra Mussels
Ingested by Blue Catfish
30
(N = 140)
25
20
15
10
5
0
228.6 254 279.4 304.8 330.2 355.6 381 406.4 431.8 457.2 482.6 508 533.4 558.8 584.2 609.6 635
Blue Catfish Size Class (mm)
Zebra Mussel Clusters
Zebra Mussels in Blue Catfish
Major Points
• Blue catfish are a new and important
predator of zebra mussels.
– 53% of blue catfish contained zebra mussels
• Blue catfish show seasonal prey shifts,
consuming zebra mussels in summer
and shad in winter.
– Alternation between native species and
introduced species
• All size classes of blue catfish consume
zebra mussels extensively.
Energetics
Caloric Analyses of Primary Prey Species
Gizzard Shad
Dorosoma cepedianum
Threadfin Shad
Dorosoma petenense
Asiatic Clam
Corbicula fluminea
Zebra Mussels
Dreissena polymorpha
Drying Oven
Muffle Furnace
Ash Determination and Correction
Ash Free Dry Mass
-1
Joules g (x1000)
35
30
25
20
15
Threadfin Shad
Gizzard Shad
Zebra Mussel
Asiatic Clam
10
5
0
Spring
Sum/Fall
Season
Winter
-1
Joules g (x1000)
30
Whole Organism Dry Mass
25
Threadfin Shad
Gizzard Shad
Zebra Mussel
Asiatic Clam
20
4
2
0
Spring
Sum/Fall
Season
Winter
Zebra Mussel Consumption and Growth of
Freshwater Drum in Lake Erie
Graph From Study by French and Bur (1991)
375
325
present study (1991)
1978 (Bur 1984)
1958 (Edsall 1967)
275
225
175
2
3
4
5
Age
6
7
Major Points
• Energy content of bivalves was
significantly less than that of shad.
• Energy content showed a significant
interaction between prey species and
season.
• Shad had significantly greater energy
content than bivalves in any season.
– Whole organism energy content of shad was order
of magnitude greater than bivalves.
• Quantity vs. quality?
Conclusions
• Zebra mussels have become an important prey
item for freshwater drum, redear sunfish, and blue
catfish in Lake Dardanelle and the Arkansas
River.
– Adult blue catfish forage extensively on all sizes of
zebra mussels.
– Blue catfish show a seasonal prey shift, feeding on
zebra mussels in summer and shad in winter.
• Zebra mussels and asiatic clams are significantly
lower in caloric value than gizzard and threadfin
shad.
– Quantity vs quality?
– Prey profitability? (Capture success, handling time,
evacuation rates, prey density, season)
Energy Budget in Individual Fish
P=C-(F+U)-R or C=P+F+U+R
36
Abiotic Factors affect
Bioenergetics
Temperature affects all
of the budget variables
37
Blue Catfish Prey Consumption
based on Bioenergetics Model
Greater biomass of
zebra mussels than
shad were consumed
by all size classes
38
Blue Catfish Production and Prey
Use
Gross production
tracks shad
consumption
39