Algal Succession and Variability

 In the previous experiment, it was shown that each lake will have its own unique values for chlorophyll and phycocyanin. Concentrations between lakes can easily vary by 20X. Concentrations of chlorophyll and phycocyanin within a single lake can vary based upon the physical, chemical and biological conditions that are influenced by the location and the time of year. This is referred to as spatial and temporal variability. This can easily be observed by sampling at different locations over a period of time and evaluating the changes in the chlorophyll and phycocyanin levels. The values tend to fluctuate in patterns that provide insight into the composition of the algae.

The composition of the phytoplankton community can be evaluated by calculating a PC/Chla Ratio. For example, as the cyanobacteria population increases, the PC/Chla Ratio will increase as well. The changes in the PC/Chla Ratio reflects the process of algal succession, whereby certain types of phytoplankton will dominate at one time to be replaced by another.  

You will be working with chlorophyll and phycocyanin data taken from a single lake at two different sites over a time period of 6 weeks. An example of the data representing spatial variability of phycocyanin is depicted in Figure 1. An example of the data representing temporal variability of phycocyanin is depicted in Figure 2.  An example of the data representing algal succession is depicted in Figure 3.


(click graphs to enlarge)