Secchi Disk

The Secchi Disk is used to measure how much light penetrates the upper layer of the ocean. A schematic drawing of how the Secchi disk works is shown below.

QUESTIONS

• What weather is best for good light penetration into the water?

 

• What time of year is best for good light penetration (in the absence of plankton.)?

 

• Phytoplankton (tiny marine plants) thrive where there is an abundance of nutrients and sun. What time of year would you expect plankton to thrive? Oceanographers term a thriving phytoplankton community a "plankton bloom".

 

• If there are lots of plankton in the water, what would be the effect on a Secchi disk measurement?