CCE-LTER determines the size distribution of total chlorophyll a by filtering water though filters of differing pore sizes, extracting these in acetone and analyzing fluorometrically. Using size fractionation of chlorophyll a and taxon-specific pigments (chlorophylls and carotenoids) from HPLC analysis, the samples analyzed within the California Current Ecosystem are used to develop a metric for phytoplankton community structure that can be used to monitor its state and changes thereof over time.
Complete methods for chlorophyll a size fractionation can be found here.
For the size fractionation of chlorophyll a, a 10 meter depth sample of seawater is collected, filtered in parallel through filters with five different pore sizes (GF/F filters, 1 µm, 3 µm and 8 µm, and 20 µm pore sizes), and these are extracted in 90% acetone for 24 hours in the dark at -20°C for standard fluorometric analysis. Each size treatment has 3 replicates.
Water for size fractionation of chlorophyll a is sampled from a 10m depth on Line 83 and 87 with scattered inshore stations within the CalCOFI and SCCOOS stations located in the CCE. A seawater sample (about 4.5 - 5 liters) is collected from the niskin bottle in a 10 liter carboy.