What is Phycoerythrin?
Phycoerythrin is a type of blue-green pigment found in some phytoplankton, such as Cyanobacteria and Cryptophyceae. Phycoerythrin is measured as a concentration in cells per milliliter (cells/mL). Because Phycoerythrin is contained within blue-green phytoplankton, it can be used as an indicator for the amount of Cyanobacteria present in the water.
Why is Phycoerythrin important?
As an indicator for the amount of blue-green phytoplankton in waterways, Phycoerythrin is important for determining whether Cyanobacteria are present at ecologically healthy levels. When too much nutrients pollution, measured by Total Nitrogen and Total Phosphorus, is present in the water, Cyanobacteria will rapidly reproduce, resulting in blooms comprised of potentially-harmful species that secrete toxins that under some circumstances may stress or kill fish and other aquatic animals. Less often, these toxins may also pose a risk to humans.
How do we measure Phycoerythrin?
Phycoerythrin is measured with an optical probe that is lowered from our WATERKEEPER boat into the water at each station location. Phycoerythrin readings are automatically collected at 0.5 or 0.25 meter intervals from the water’s surface to just above the river bottom. We assess the Phycoerythrin data for readings collected above the pycnocline [wiki hyperlink here] using the World Health Organization’s numeric human health threshold of 20,000 cells/mL.