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Light Intensity and Water Clarity Comparison in Lakes. Adam Evans Heather Bradley. Importance of Light. Energy Source: Photosynthesis Thermal Structure Determines species structure and lake metabolism Water Chemistry Nutrient Cycling. Light Intensity and Quality. Scattering off particles
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Light Intensity and Water Clarity Comparison in Lakes Adam Evans Heather Bradley
Importance of Light • Energy Source: Photosynthesis • Thermal Structure • Determines species structure and lake metabolism • Water Chemistry • Nutrient Cycling
Light Intensity and Quality Scattering off particles Refraction from density changes Reflection dependent on light angle, waves, clouds Absorption by gases and water Attenuation due to absorption and scattering
Methods • To obtain our light data we traveled to local lakes (around Syracuse area) and also to Huntington Forest in the NE Adirondacks • In each lake we took a surface or deck reading of incident light with a spectrometer and then lowered the device to different consecutive depths to record changes in light intensity • We used a Secchi disk to measure the visibility of each lake
Results • Light pattern was characteristic of a shallow productive lake • Sufficient light in the first 2 meters available for photosynthesis • Light Compensation point is around 5 meters depth
Hyper-eutrophic lake with no light reaching • depths below 8 meters • Compensation point around 5 meters • Characteristic curve
Light available for photosynthesis in first 2 meters • Compensation point around 2 meters • Shallow lake
Oligotrohic lake with compensation point around 7 meters • Large epilimnion where photosynthesis can occur
Light reaching lake bottom sediments • Intensity decreases steadily from depths 2m to 3m • Uniform intensity in the top 2 meters • Shallow lake, no compensation point
Unusual Curve, doesn’t reach 1% light • Increases and decreases in light perhaps due to • Stratification layers of different densities or sampling • error • Oligotrophic meromictic lake
Green Arbutus Rich • Oneida and Green Lakes are the clearest and most oligotrophic and thus have a higher K value • Deer, Rich, and Arbutus lakes are all productive and slightly eutrophic with some suspended particles • Onondaga Lake is hypereutrophic with the lowest water clarity and light penetration