A Limnological Assessment: The Lucas Pond
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Transcript of A Limnological Assessment: The Lucas Pond
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A Limnological Assessment: The Lucas PondChristian BrownDylan GollenTaylor LasleyJohn Novak
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Overview
• Objectives• Methods and Materials• Results• Discussion• Implications
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Team Objectives
Sediment Analysis
Macro Invertebrate Assessment
• Identify species present• Enumerate densities
• Water content• Organic matter
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Methods and Materials
Field Equipment
• KB Core sampler• Ekman grab sampler• Pencils, notebook, tape • Storage containers
Lab Equipment
• Digital scale and weigh boats• Oven• Metric ruler
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Methods and MaterialsSampling Design• KB core and Ekman samples were taken in a balanced manner
that encompassed the greatest area of the pond • Seven samples total for each sampling method• Two samples from east and west sites• Three replicates from middle site
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Methods and Materials
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Methods and Materials
Analyzing KB Core SamplesWater Content• measured total core depth (cm)• removed 1cm sections • recorded wet weights of each
section• placed samples in oven, then
recorded dry weights
Percent Water Content = Wet weight-dry weight/wet weight
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Methods and Materials
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Methods and Materials
Organic Matter• Placed dried samples into
oven for burning
• Recorded ash weight
Percent organic matter = dry weight – burn weight/ dry weight
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Methods and MaterialsBenthic macro invertebrates• collected with Ekman grab
sampler• Same sample sites• Samples filtered through wash
bucket (remove sediment)• samples were stored and
preserved in ethanol solution • species identified and
enumerated using dissecting microscopes
• densities were converted from Ekman volume (225cm2) to number per square meter
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Results
Figure 2.-Plot of water content versus sediment depth for the Lucas pond in Latah Co. Moscow, Idaho USA on October 9, 2013.
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Results
Figure 1. - Plot of organic matter versus sediment depth, using core sections taken with a KB corer at the Lucas pond in Latah Co. Moscow, Idaho USA on October 9, 2013.
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Results
Table 1. Paired t-test for organic matter and water content between the east and west sample sites in the Lucas pond on October 9, 2013.Sample t df n p Organic Matter (%) 3.412224599 9 10 0.007722 Water Content (%) 13.55686461 9 10 2.71E-07
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Results
Sample t df n pBenthic Macro -2.178199633 2 3 0.080636
Table 2. Paired t test between benthic macro invertebrate counts from the east and west sampling sites in the Lucas
pond on October 9, 2013.
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Discussion
Sediment Accumulation
• Pond size• Steep catchment• Surrounded by granitic
Gneiss rock• Allocthonous inputs
from vegetation and rock
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Discussion
Benthic Macro-Invertebrates• Relatively high abundance • Chaoborus, Chironimids, and
Oligochetes contribute to bioturbation (Ademek et al. 2009)
• Mechanical mixing of sediment through construction of feeding tubes and burrows
• Affects transport of nutrients, particularly P and N
• Increases oxygen penetration into sediment which enhances mineralization process by which nutrients are released into the overlying water
• Inhibition of phytoplankton and benthic macrophyte growth
• Chironomid larvae can increase nutrient enrichment which can eventually lead to eutrophication
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Implications• When considering the benthic aspects of the Lucas pond the
longevity is dependent upon:
• High rates of total sediment and organic matter accumulation• Unchecked population of benthic macro invertebrates could
diminish pond water quality through process of bioturbation
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Literature cited• Ademek, Z. Marsalek, B. 2013. Bioturbation of sediments by
macroinvertebrates and fish and its implication for pond ecosystems: a review. Aquaculture Int. 21:1-17
• Brainard, A. S. Fairchild, G.W. 2012. Sediment characteristics and accumulation rates in constructed ponds. Journal of Soil and Water conservation. Vol. 67, no. 5. pp. 425-432
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QUESTIONS