Js. Cleveland et Mj. Perry, A MODEL FOR PARTITIONING PARTICULATE ABSORPTION INTO PHYTOPLANKTONIC AND DETRITAL COMPONENTS, Deep-sea research. Part 1. Oceanographic research papers, 41(1), 1994, pp. 197-221
A model for partitioning total particulate absorption, measured on gla
ss fiber filters, into phytoplanktonic and detrital components is deve
loped. The model reconstructs absorption spectra for living phytoplank
ton using total particulate absorption at the red absorption maxima fo
r chlorophylls a and b, concentrations of chlorophyll a and pheopigmen
t, and mean normalized absorption spectra for laboratory-grown algal c
ultures. The model was developed in stages for two types of phytoplank
ton assemblages. Section A of the model applies to waters dominated by
eukaryotic algae and is based on absorption spectra for chromophytic
(phytoplankton containing chlorophyll c) and chlorophytic (containing
chlorophyll b) species. Section B of the model. allowing more variabil
ity in spectral shape, was developed for algal communities with more d
iverse pigmentation. All spectra are processed through Section A. with
an internal evaluation determining whether processing continues throu
gh Section B. Detrital spectra, generated as the difference between to
tal particulate and modelled phytoplanktonic spectra, included pheopig
ment absorption and had high blue absorption. Blind tests on samples o
f known composition predicted absorption within 8-10% at 436 nm and 1-
13% when averaged from 400 to 700 nm, which is within the expected acc
uracy of the glass fiber filter method. No true measure of phytoplankt
on absorption in field samples is available for testing the model, but
results from methanol-extractions were used for comparison despite in
clusion of pheopigment absorption as ''phytoplankton''. For samples co
llected from coastal waters of Washington State, the Sargasso Sea and
coastal waters of Norway, modelled absorption (averaged over 400-700 n
m) ranged from 25% lower to 0.5% higher than the methanol-extraction r
esults; pheopigment absorption inappropriately included in the phytopl
ankton component accounts for the higher phytoplanktonic absorption es
timated by the methanol technique. Successful application of the model
to samples from widespread locations, of different absorption magnitu
des, and with varied spectral shapes indicate that the model can be us
ed in diverse environments.