Seasonal variation in light, mixing depth and primary productivity in temperate northern hemisphere waters
- Become more skilled in reading and interpreting semi log graphs, temperature profiles, and time series plots.
- Practice unit conversions.
- Gain an understanding of k, the attenuation coefficient for nondirectional light.
- See how the depth of the photic zone and the surface mixed layer varies seasonally at temperate latitudes and how this relates to seasonal phytoplankton productivity dynamics.
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
- Reinforce concept of water column structure.
- Link water column structure and photic zone depth to primary productivity.
Higher order thinking skills goals for this activity
- Students analyze data by plotting time series of different variables and then interpret the plots.
- Students hypothesize about complex relationships between biology and the physical/chemical environment in the ocean.
Other skills goals for this activity
Students calculate a conversion factor to do a unit conversion. This can later be applied when manipulating data in spreadsheets.
Description and Teaching Materials
Light in the ocean - student handout (Microsoft Word 2007 (.docx) 283kB Jan24 14)
Light in the ocean - instructor solutions (Microsoft Word 2007 (.docx) 267kB Jan24 14)
Teaching Notes and Tips
- Many students do not know how to read semilog graphs. To bring everyone up to speed count, with the class, through several cycles.
- This exercise helps students see how data are used to understand a scientific process.
- You may mention that students will derive the light intensity equation when/if they take differential equations.
References and Resources
Knauss, J.A. 1978. Introduction to Physical Oceanography. Prentice-Hall, Inc. Englewood Cliffs, N.J.
Open University Course Team. 1995. Seawater: Its Composition, Properties and Behavior. 2nd ed. Jointly published by The Open University and Pergamon, an imprint of Elsevier Science Ltd., Oxford.
Sverdrup, H.U., Johnson, M.W. and Fleming R.H. The Oceans, Their Physics, Chemistry and General Biology. 1942. Prentice-Hall, Inc., Englewood Cliffs, N.J.