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Zooplankton Analysis of Blue Lake October 23 rd , 2010. Ben Majsterek , Mary Coyle, Jackie Hancock, and Mary Ruskovich. Introduction. Kettle lake formation, heavy macrophytes , and extremely thick sediment along bottom “bottomless lake” - PowerPoint PPT Presentation
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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
1
2
3
4
5
6
7
8
9M
ean
Indi
vidu
als/
L
Mean individuals/L for ceriodaphnia, cyclopoid, and diaphanosoma: 6.33, 7.66, and .333 individuals/L
Ceriod
aphn
ia
Lepto
dora
Cyclop
oid
Diapha
noso
ma
Calano
id
Harpac
ticoid
0
1
2
3
4
5
6
7
8
9
10
Mea
n Id
ivid
uals
/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
2
4
6
8
10
12
Mea
n In
divi
dual
/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
1
2
3
4
5
6
7
Mea
n i
ndiv
idua
ls/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
20
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 feedCurrent 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