Estimating Phytoplankton Biomass using Fluorometry

Overview: The levels of the pigments (Chla and PC) and their relative proportions of (PC/Chla Ratio) will change throughout the year. Three different types of samples will be used for the experiments, including the whole lake water collected with the integrated tube sampler (IT), the net plankton sample collected with the Students Plankton Net (Net) and the bloom-forming cyanobacteria (BFC) collected from the process to concentrate cyanobacteria.

Use a sample of distilled water to take “blank” readings on the fluorometer for phycocyanin and chlorophyll-a. Have each student write this blank value in their notebook. Take readings for phycocyanin and chlorophyll-a for each type of sample from each student with single readings for “IT”, “Net” and “BFC”. Have the students make note of their readings, subtract the blank values, and record their final readings.

Make a data table for all the readings in groups of three on the chalkboard. Have each student fill in their values of their readings. Once completed, have the students calculate the average PC, Chla values and PC/Chla ratios for each type of sample.

Create individual graphs (scatterplots/bar graphs) for PC, Chla and PC/Chla ratios for each type of sample. An example graph is shown in Figure 1 . The graphs shown in Figure 2 offer a comparison of PC values between different lakes for the different types of samples.

Figure 1

(click graph to enlarge)

Figure 2

(click graph to enlarge)