Premium
Variability in light absorption and scattering of phytoplankton in Patagonian waters: Role of community size structure and pigment composition
Author(s) -
Ferreira Amabile,
Stramski Dariusz,
Garcia Carlos A. E.,
Garcia Virginia M. T.,
Ciotti Áurea M.,
Mendes Carlos R. B.
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/jgrc.20082
Subject(s) - phytoplankton , chlorophyll a , absorption (acoustics) , particulates , oceanography , chemistry , environmental chemistry , environmental science , biology , physics , botany , ecology , nutrient , geology , optics
Intense phytoplankton blooms were observed along the Patagonian shelf‐break with satellite ocean color data, but few in situ optical observations were made in that region. We examine the variability of phytoplankton absorption and particulate scattering coefficients during such blooms on the basis of field data. The chlorophyll‐ a concentration, [Chla], ranged from 0.1 to 22.3 mg m −3 in surface waters. The size fractionation of [Chla] showed that 80% of samples were dominated by nanophytoplankton (N‐group) and 20% by microphytoplankton (M‐group). Chlorophyll‐specific phytoplankton absorption coefficients at 440 and 676 nm, a * ph (440) and a * ph (676), and particulate scattering coefficient at 660 nm, b * p (660), ranged from 0.018 to 0.173, 0.009 to 0.046, and 0.031 to 2.37 m 2 (mg Chl a ) −1 , respectively. Both a * ph (440) and a * ph (676) were statistically higher for the N‐group than M‐group and also considerably higher than expected from global trends as a function of [Chla]. This result suggests that size of phytoplankton cells in Patagonian waters tends to be smaller than in other regions at similar [Chla]. The phytoplankton cell size parameter, S f , derived from phytoplankton absorption spectra, proved to be useful for interpreting the variability in the data around the general inverse dependence of a * ph (440), a * ph (676), and b * p (660) on [Chla]. S f also showed a pattern along the increasing trend of a * ph (440) and a * ph (676) as a function of the ratios of some accessory pigments to [Chla]. Our results suggest that the variability in phytoplankton absorption and scattering coefficients in Patagonian waters is caused primarily by changes in the dominant phytoplankton cell size accompanied by covariation in the concentrations of accessory pigments.