Zooplankton Analysis of Blue Lake October 23rd, 2010

Ben Majsterek, Mary Coyle, Jackie Hancock, and Mary Ruskovich

Introduction

• Kettle lake formation, heavy macrophytes, and extremely thick sediment along bottom “bottomless lake”

• 100’s of bullhead catfish as well as 60 hatchery rainbow trout stocked ~2 years ago

• Used for fishing, boating, swimming, and as aesthetic appeal

• Goal: reduce macrophytes and algae, increase zooplankton abundance, properly manage fish stocks, maximize recreational use

Methods

• Site selection– Li-Cor meter – aphotic vs photic– Temperature profile – unstratified

• Northeast to Southwest transect– Five locations, 3 replicates, entire water column with a

12.5 cm closing plankton net

• Preserved with formalin for 2 weeks and analyzed at the U of I lab to determine zooplankton density and species distribution

Location of SitesBlue Lake Oct. 23rd , 2010

1

2

3

4

5

Site 1

Ceriodaphnia Cyclopid Daiphanosoma0

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2

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7

8

9

Me

an

In

div

idu

als

/L

Mean individuals/L for ceriodaphnia, cyclopoid, and diaphanosoma: 6.33, 7.66, and .333 individuals/L

Ceriod

aphn

ia

Lept

odor

a

Cyclop

oid

Diapha

noso

ma

Calano

id

Harpa

ctico

id0

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5

6

7

8

9

10

Me

an

Id

ivid

ua

ls/L

Site 2: Mean individuals/L for ceriodaphnia, leptodora, cyclopoid, diaphanosoma, calanoid, harpacticoid: 8.33, 0.66, 9.33, 1.66, 2 and 0.66 individuals/L

Site 2

Ceriodaphnia Leptodora Cyclopoid Bosmina0

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4

6

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10

12

Me

an

In

div

idu

al/L

Site 3

Mean individuals/L for ceriodaphnia, leptodora, cyclopoid, and bosmina: 10, 0.33, 3.33, and 0.33 individuals/L

Cerio-daphnia

Leptodora Cyclopoid Bosmina0

1

2

3

4

5

6

7

8M

ean

idiv

idua

ls/L

Mean individuals/L for ceriodaphnia, leptodora, cyclopoid, and bosmina: 7.33, 0.33, 5.33 and 0.33 individuals/L

Site 4

Ceriodaphnia Leptodora Cyclopoid Diaphanosoma Calanoid0

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6

7

Mea

n

indi

vidu

als/

L

Mean individuals/L for ceriodaphnia, leptodora, cyclopoid, diaphanosoma, and calanoid: 6, 1.66. 2.33, 0.33, and 1 individuals/L

Site 5

Ceriodaphnia Leptodora Cyclopoid Diaphanosoma Calanoid Harpacticoid Bosmina0

5

10

15

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25

30

35

40

Total individuals/L for sites 1-5. Individuals/L for ceriodaphnia, leptodora, cyclopoid, diaphanosoma, calanoid, harpacticoid, and bosmina are 38, 3, 28, 2.33, 3, 0.67, and 0.67

Zooplankton

Ceriodaphnia Cyclopoid copepod

Calanoid copepod Bosmina

(Jones, B. 2006)

Fish Species

• Bullhead Catfish (Ameiurus spp.)– Diet: plants, detritus, small fish, worms and

zooplankton

• Rainbow Trout– Diet: midges, Diptera, Ephemeroptera, and

Nemouridae larvae, fish, large zooplankton

• Largemouth Bass– Diet: crustaceans, variety of invertebrates,

fish, and odonate nymphs

Discussion• Significant absence of large zooplankton

– Fast growth in trout when first stocked– Large bullhead population

• Changes (recent rainbow trout addition) may have long term effects – increased eutrophication– Increased dependency on human supplied feed

Current management structures and goals cannot be met without change in other

aspects

Alternatives

• Ecological Improvement (swimming, aesthetic improvement, improved clarity)– Reduction of trout and bullhead stocks

• Fishery Improvement– Continual feeding of trout– Cons: may have long term effects – increased eutrophication

• Change fishery structure– Movement from trout fishery to bass – Removal of a large portion of bullhead population

Conclusion

• Zooplankton stocks are depleted and cannot sustain current fish populations alone

• To improve any aspect of the lake, another factor will have to change

i.e. continued fish stocks at these numbers and nutrient levels will may result in murky, algae filled water

References• Ahrenstorff, T. D. and M. R. Helmus. 2009. The influence of littoral zone

coarse woody habitat on home range size, spatial distribution, and feeding ecology of largemouth bass (Micropterus salmoides). Hydrobiologia 623:223-233.

• Cisneros, R., E. Hooker, and L.E. Velasquez. 1991. Natural diet of herbivorous zooplankton in Lake Xolotlan (Managua). Aquatic Ecology. 25: 163-167.

• Jones, B. 2006. Limnology. Indiana University. http://classwebs.spea.indiana.edu/joneswi/e455/

• Newell, A. E. 1960. Biological survey of the lakes and ponds in Coos, Grafton and Carroll Counties. New Hampshire Fish Game Surv. Rep. 8a:297.

• Harlan, J. R. and E. B. Speaker. 1956. Iowa fish and fishing. 3rd Ed. State of Iowa. 377pp. 

• Steiner L.  2002.  Pennsylvania Fishes.  117-123 http://www.fish.state.pa.us/pafish/fishhtms/chap13.htm