Benthic Analysis: Mr. Ingle’s Pond

X GroupTarah JohnsonMcClure ToschStephen WellsLance Keller

Overview

• Objectives

• Study Area

• Materials & Methods

• Results

• Conclusions

• Summary

Objectives

• Sediment Type

• Organic material

• Benthic invertebrate population

Study Area

• Deep: 9’2”• Shallow: 3’ 5”

Methods

• Assessment was split into two parts:

– Benthic sampling for macro invertebrates

• Eckman Dredge• 15 cm x 15 cm

– Weight sampling for sediment loading and organic concentration

• KB corer• 2 inches in diameter

Methods

• Both assessments were taken in triplicate totaling 6 samples each– Deep

• 3 Eckman Dredge samples• 3 Core samples

– Shallow• 3 Eckman Dredge samples• 3 Core samples

Methods: Eckman Samples

• Sieved on site

• Biota preserved with formalin

• Transported to lab for analysis

Methods: Eckman Samples

• Filtered to wash off formalin– 80 micrometer (μm) sieve

• Large samples– Sub-sampled when needed

• Observed under dissecting scope – Counted and identified to family

• T-test and an ANOVA – Difference in count and composition

Methods: Core Samples

• Core samples were sectioned on site

– 2cm sub-sample to 10cm

• Wet weight– Crucible weight

(zeroed out)– Crucible +

sediment sample

Methods: Core Samples

• Oven Dry Weight– 24 hours at 150° C

• Organic Weight– Furnace: 3 hours at 500° C

• T-test and an ANOVA – difference in composition between shallow

and deep samples.

Results: Profiles

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0 5 10 15 20

Temperature (°C); O2 (mg/L); pH

Dept

h (m

)

h

Temp (°C)02 pH

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0.5

1

1.5

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2.5

0 200 400 600 800 1000

Light (µmol/m2/s)

Dept

h (m

)

(m)

Results: Eckman SamplesChironomus Density

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6000

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10000

12000

Sample Location

Den

sity

(pe

r sq

met

er)

Shallow

Deep

Chaoborus Density

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20000

40000

60000

Sample Location

Den

sity

(pe

r sq

met

er)

Shallow

Deep

Results: Eckman Samples

• Greater Diversity in shallow samples

• Shallow samples were more even distributed

• Shallow samples had more taxa

Shannon's Diversity Index (log 10)

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0.5

Sample Location

Sha

nnon

's H

'

Shallow

Deep

Results: Eckman Samples

• Major Taxa Found

- Chaoboridae

- Chironomus

• Minor Taxa Found

- Ceratopogonidae

- Oligochaeta

Results: Core Samples

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12

40 50 60 70 80 90

Percent Moisture

Mea

n D

epth

in c

m

Shallow

Deep

Results: Core Samples

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2

4

6

8

10

12

6 8 10 12 14

Percent loss on ignition at 550 C

Mea

n D

epth

in c

m

Shallow

Deep

Results: Core Samples

• There was no difference in moisture content

• There was a difference in percent organic

• The sediment is mainly composed of silt

Conclusions

• Fish feed on Chaoboridae and Chironomus larvae (Sweetman 2006).

• Chironomus larvae suggest highly eutrophic pond (Saether 1979)

• Chaoboridae larvae specifically Chaoborus migrate vertically to avoid predation(Sweetman 2006).

Conclusions

• The percent water content suggests a silt/clay sediment

• Dr. McDaniel concluded the sediment was mostly silt

• The difference in percent organic might be from differences in Chaoboridae numbers.

Summary

• The high Chaoboridae and Chironomus populations are good fish food but might not be available to eat.

• There is a difference in organic soil content between deep and shallow probably due to Chaoboridae pop.

• There was no difference in sediment loads between the shallow and deep end of the lake.

Acknowledgments

• Mr. Ingle

• Picture Credits– iodeweb5.vliz.be/.../

AndersonBook/SampEquip.htm – Dr. Wilhelm

• Other Credits– X Group Bathometric Group– X Group Light and Temperature Profiles

References

• Jon N. Sweetman , a, and John P. Smola Reconstructing fish populations using Chaoborus (Diptera: Chaoboridae) remains – a review Paleoecological Environmental Assessment and Research Laboratory (PEARL), Department of Biology, Queen's University, Kingston, Ont., Canada K7L 3N6

• Saether, O.A. 1979. Chironomid communities as water quality indicators. – Holarct Ecol. 2: 65-74

Questions?