Nicole Bale Report from the R/V Knorr

The photosynthetic pigment, chlorophyll-a, is the most widely used measure of biological production in the ocean. When free of cellular pigment-protein complexes, chl-a is a labile molecule sensitive to light and is know to form suites of transformation products.

Any disruption to the cell will potentially alter the chlorphyll molecule. Despite the fact that 1000 million tons of chl-a are produced globally each year, its fate is still poorly understood. Transformation products of chl-a show potential as indicators of specific conditions and processes in the marine environment.

High performance liquid chromatography (HPLC) allows Nicole Bale to separate complex pigment distributions typical of natural samples. Here's Nicole with her on-board setup:

HPLC uses solvents to separate compounds in a tightly packed column. Nicole can identify the compounds by their spectral qualities (e.g., UV-visible absorption) and retention time in the column. Shown below are two chromatograms (660 nm) of pigment extracts at 30 m from two CTD stations during the R/V Knorr process cruise. Note the difference in the peak area of the degradation product "pheophorbide" relative to chl-a between the two stations.

During the NAB08 cruise, Nicole has been collecting water from CTD casts and analyzing the distribution of chlorophyll and its degradation products. Differences in the depth-distribution of chl-a and one degradation product, pheophorbide, at the same two stations are shown below.

Nicole will be performing extensive analyses like these in order to examine various phytoplankton fate processes (senescence and grazing) during the bloom.