Seasonal prey shifts and bioenergetics

Daniel D. Magoulick

Arkansas Cooperative Fish and Wildlife Research UnitDepartment of Biological Sciences

University of Arkansas - Fayetteville

Zebra MusselDreissena 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

Dardanelle Dam

Illinois BayouSpillway

N

RiverChannel

LEGEND

CreekChannel

City ofRusselville

Study Site

Predation Experiment Site

Fish CollectionSite

Zebra Mussels in Blue Catfish

Number Percent Fish Containing Containing

Predator N Size (mm) D. polymorpha 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 SelectionLake Dardanelle 1996-1999

0

20

40

60

80

100

Per

cent

age

of F

ish

(%)

7/96 9/96* 1/97 3/97 4/97 9/97* 12/97 1/98 3/98 5/98 6/98 8/98 9/98 1/99

Sample Dates

ZM

Shad

Other

Empty

0

20

40

60

80

100

Per

cent

pre

y us

e

J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J

1996 1997 1998

Gizzard Shad (Dorosoma cepedianum)

Winter Die-Off

Buoy and Sample Plates

Summer 1996

Blue Catfish Prey SelectionLake Dardanelle 1996-1999

0

20

40

60

80

100

Per

cent

age

of F

ish

(%)

7/96 9/96* 1/97 3/97 4/97 9/97* 12/97 1/98 3/98 5/98 6/98 8/98 9/98 1/99

Sample Dates

ZM

Shad

Other

Empty

0

20

40

60

80

100

Per

cent

pre

y us

e

J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J

1996 1997 1998

Zebra Mussel Die-offSummer 1997 and 1998

Zebra Mussels Consumed by Blue CatfishPredator Size Classes

0

10

20

30

40

Nu

mb

er

of F

ish

203.2 254 304.8 355.6 406.4 457.2 508 558.8 609.6 660.4 >711.2Blue Catfish Size Classes (mm)

Fish Containing Zebra Mussels Total Number of Fish/Size Class

(N = 463)

Length of Zebra MusselsIngested by Blue Catfish

0

5

10

15

20

25

30

Len

gth

(m

m)

228.6 254 279.4 304.8 330.2355.6 381 406.4431.8 457.2 482.6 508 533.4558.8 584.2 609.6 635Blue Catfish Size Class (mm)

(N = 140)

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.

EnergeticsCaloric Analyses of Primary Prey Species

Gizzard Shad

Dorosoma cepedianum

Threadfin Shad

Dorosoma petenense

Asiatic Clam

Corbicula fluminea

Zebra MusselsDreissena polymorpha

Drying Oven

Muffle Furnace

Ash Determination and Correction

Ash Free Dry Mass

Season

Joul

es g

-1(x

1000

)

0

5

10

15

20

25

30

35

Threadfin ShadGizzard ShadZebra MusselAsiatic Clam

Spring Sum/Fall Winter

Whole Organism Dry Mass

Season

Joul

es g

-1(x

1000

)

0

2

4

20

25

30

Threadfin ShadGizzard ShadZebra MusselAsiatic Clam

Spring Sum/Fall Winter

Zebra Mussel Consumption and Growth of Freshwater Drum in Lake Erie

Graph From Study by French and Bur (1991)

175

225

275

325

375

Mea

n b

ack-

calc

ula

ted

to

tal

len

gth

(m

m)

2 3 4 5 6 7Age

present study (1991)

1978 (Bur 1984)

1958 (Edsall 1967)

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)

36

Energy Budget in Individual FishP=C-(F+U)-R or C=P+F+U+R

37

Abiotic Factors affect Bioenergetics

Temperature affects all of the budget variables

38

Blue Catfish Prey Consumption based on Bioenergetics Model

Greater biomass of zebra mussels than shad were consumed by all size classes

39

Blue Catfish Production and Prey Use

Gross production tracks shad consumption