1. Light and Secchi Measurements Erick, Brie, Reddy, Kevin

2. Data Collection Data was collected using: –Secchi Disk –Photometer

3. Data Manipulations Photometer gives us a % of light transmitted to a depth relative to irradiance at the surface S0… we had to account for changing surface light levels To do this we had to correct the spherical values

4. Manipulations Cont. We found a ratio of deck irradiance at the time of initial sample and the deck irradiance at the time of sample Z. We then divided the sphere value by this ratio to make a RELATIVE FIGURE

5. Figures and Graphs

6. Green Lake

7. Onieda Lake

8. Catlin Lake

9. Arbutus Lake

10. Onondaga Lake

11. Rich Lake

12. Attenuation Coefficients

13. Factors Affecting Observations The degrees of light penetration in a lake can determine: –Photosynthetic rates as well as metabolism –thermal structure of the lake –biota types and community structures Factors affecting light intensity: –latitude/altitude –solar angle –cloud cover The degree of light penetration is determined in part by: –reflection –scatter/absorption –refraction

14. Observations

16. Further Measurements and Sources of Error Sources of error include: –Calabration error –The Secchi disk is a very rough estimate--it may vary greatly

17. Cont. Other Measurements: –Possibly measure specific wavelengths rather than % of light. This might give us a better picture of what is actually limiting light. –Measure vegetation limits- tells us where there is insufficient light for photosynthesis.