Light and Secchi Measurements Erick, Brie, Reddy, Kevin

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

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

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

Figures and Graphs

Green Lake

Onieda Lake

Catlin Lake

Arbutus Lake

Onondaga Lake

Rich Lake

Attenuation Coefficients

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

Observations

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

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.