Phytoplankton Biomass and Environmental Metrics

Scientists are always challenged to provide useful information on the occurrence and severity of algal blooms in aquatic systems. Challenges in surveillance programs include the location and timing of the blooms due to patchiness of the phytoplankton, along with the composition of the phytoplankton community due to algal succession.

To address these limitations, scientists try to use simple, inexpensive monitoring techniques to quantify and understand what is happening in the waterbody. Some of these techniques include the use of Secchi disk depth, in-situ fluorometry for phycocyanin (PC) and chlorophyll-a (Chl-a), cyanobacteria biovolume (um3/ml) and cell densities (#cells/ml). These parameters can be compared to each other through a regression analysis to determine if there is a significant relationship between them. This relationship can help scientist predict what might happen in the future, and whether a harmful bloom might occur. When relationships are established and continue to be observed, scientists can consider these relationships as environmental metrics. Environmental metrics provide an inexpensive and timely source of information to environmental managers so they can alert the public to any potential health risks.

The methods that scientists use to collect the samples will follow certain protocols. Sometimes, when scientists want to experiment with new metrics, they will develop new methods. Some previous studies using metrics have used sampling techniques including vertically integrated tows (1M and 3M depth) and net plankton tows (3M depth). A vertically integrated tow uses an integrated tube sampler and a net plankton tow uses a plankton net. All samples were analyzed as “in-situ” samples for Chl-a and PC.

This experiment will use existing data to construct environmental metrics, including Secchi disk depth (SDD), Chlorophyll-a (Chla) and phycocyanin (PC). Samples were obtained using the integrated tube sampler and net plankton tows at a depth of 3 meters. Samples were either completely mixed (T=0) or allowed to separate for 30 minutes (T=30). Samples will be analyzed as in-situ or frozen. The information provided should challenge students to observe existing conditions and predict future trends in the quality of the aquatic system.

(click graphs to enlarge)