Thad Grant Abu Andrew Kara 12/10/2008 1. Objectives Methods and Materials Results & Discussions Conclusion & Recommendation Limitations 12/10/2008.

1

Sediment Depth Accumulation Analysis and

Deepwater Macroinvertabrates

Thad Grant

Abu Andrew

Kara

12/10/2008

2

Objectives Methods and Materials Results & Discussions Conclusion & Recommendation Limitations

Outline

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Hypothesis: There is more

sediment accumulation in the deepest region compared to the shallower areas

Macroinvertebrates are more abundant at shallower depths than those in the deeper areas

Objectives: Determination of sediment

accumulation at the deeper and shallower regions of the lake; sediment layers and organic matter content will be the key indicators of the comparison.

Determination of macroinvertebrate density at the same regions as described above.

Study Objectives

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Description of the Baron pond Sampling techniques Laboratory analysis

Figure 1 map of Baron pond

Showing sampling points 11/5/08

Methods

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We took three K-B corer samples and one Ekman grab from the deepest point (3meters)

We took two other Ekman grab samples and KB-core samples from the shore (1.5 meters) and mid-depth (1.9 meters)

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Sampling Techniques

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Each determined amount of sample (2 cm) were placed in crucibles.

Samples were dried for more than 24 hours in the drier.

After dry weights were recorded the samples were placed in a muffle furnace to ash the samples 550 ºC for 3 hours.

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Laboratory Analysis

7

0

5

10

15

20

25

30To

tal

De

pth

of

Co

re

Sa

mp

le (

cm

)

Shore Middle Deepest

Fig 2 Sediment depth of samples from the three points 11/5/08

Results (Sediment depth)

Greatest at the middle (24.33cm), followed by the deepest point (19.33cm), and then the shore (8.89cm)

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67

68

69

70

71

72

73

74

%Moisture

%m

ois

ture

(A

v)

Shore middle deepest

Results

Moisture content was highest for sediment close to shore (73.4%), followed by the middle point (72.0%), and then the deepest (69.6%)

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Fig 3: % moisture of sediment samples 11/5/08

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Results55 60 65 70 75 80 85 90

0

2

4

6

8

10

12

Series1

% Moisture

Sedim

ent

Depth

(cm

)

Average % moisture at sediment depth for all samples

10

Results (sediment & moisture)

Factoring in the % moisture, the deepest point might have had more sediment than any other point, based on the assumption that soil aggregates become compacted with less moisture.

Further clarification needed: aggregate stability depends on particle size, OM and moisture content (Haynes et al 2006)

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Shore Middle Deepest0

10

20

30

40

50

60

70

80

8.89

24.3319.33

73.399256423164

72.0084840302551 69.637377595

6757

Sediment depth% Organic Matter

Fig 4 sediment and % moisture of samples 11/5/08

11

0

2

4

6

8

10

12

14

16

% Organic Matter%

Org

anic

Matt

er

(Av.)

Shore Middle Deepest

Results

Organic Matter was highest close to shore (13.63), followed by the middle (10.37) and the deepest point (9.37)

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Fig 5: % OM of samples 11/5/08

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Results6 8 10 12 14 16 18 20 22

0

2

4

6

8

10

12

Series1

% Organic Matter

Sedim

ent

Depth

(cm

)

Average % organic matter at sediment depth for all samples

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Organic matter (OM) & sediment depth

0

5

10

15

20

25

30

Sediment depth (cm)Organic Matter (%)

Shore Middle Deepest

More OM contributed to sediment depth at the shore, compared to the other two sampling points

Deposition of OM seemed to follow from the shore to the middle (the second highest), and the deepest point.

OM content is useful in explaining benthic communities in terms of age, redox potentials, faunal presence and abundance, etc. (Mayers, et al. 1998).

Differences in OM at the three depths could be useful in determining the sediment age. This however could be obvious if there is information on the rate of material breakdown.

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Fig 6: OM & sediment depth of samples 11/5/08

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Results (Macroinvertebrates)

Chaoborus population increased with depth, the reverse was the case for chironomids

Rivet hypothesis: Each spp has the potential to perform an essential role in the persistence of the community & the ecosystem; some represent a particular functional group (Ehrlich et al. 1998, Covich et al. 1999).

Chaoborus induces morphological change in Daphnia (Hebert et al. 1985)

Availability of food materials govern the distribution of chironomid communities (Saether O.A 1979)

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Shore Middle Deepest0

500100015002000250030003500400045005000

ChironomidsChaoborus

Fig 7 population density of macroinvertebrates at the Baron pond 12/5/08

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Sediment accumulation could be greatest at the middle depth (shelf). This might be due to contribution from the piece of land in the middle, in addition to those from the shore

Organic matter is the greatest contributor to the sediment accumulation

Macroinvertebrate community is dominated by Chaoborus, which is greatest at the deepest depth.

Conclusion

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Further investigation with replicate samples is needed to insure the precision of our findings

Labels that resist high temperature are recommended, this limited the reproducibility of our samples

The true picture of the benthic community cannot be divorced from the biotic/abiotic factors of the water column

Limitations & Recommendations

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Covich A. P.; Palmer M. A.; Crowl T. A. The Role of Benthic Invertebrate Species in Freshwater Ecosystems: Zoobenthic species influence energy flows and nutrient cycling. BioScience, Volume 49, Number 2, 1 February 1999, pp. 119-127(9)

Hebert, Paul D. N.; Grewe, Peter M. Chaoborus-induced shifts in the morphology of Daphnia ambigual. Limnol. Oceanogr., 30(6), 1985, 1291-1297

  Haynes, R. J.; Swift, R. S. Stability of soil aggregates in relation to organic

constituents and soil water content. European Journal of Soil Science Volume 41 Issue 1, Pages 73 – 83 Published Online: 28 Jul 2006

  Meyers, Philip A..; Lallier-Vergès, Elisabeth. Lacustrine sedimentary organic

matter records of Late Quaternary paleoclimates. Journal of Paleolimnology 21: 345–372, 1999. 345 © 1999 Kluwer Academic Publishers. Printed in the Netherlands.

Saether, Ole A. Chironomid communities as water quality indicators Ecography Volume 2 Issue 2, Pages 65 – 74. Published Online: 30 Jun 2006

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Reference List