Ciotti, A. M.. Dalhousie University, aurea@raptor.ocean.dal.ca
Cullen, J. M.. Dalhousie University, john.cullen@dal.ca
Huot, Y. Dalhousie University, yhuot@raptor.ocean.dal.ca
Lewis, M. R.. Dalhousie University, marlon@raptor.ocean.dal.ca

 
DOMINANT CELL SIZE IN NATURAL PHYTOPLANKTON COMMUNITIES, THE SPECTRAL SHAPE OF THE ABSORPTION COEFFICIENT, AND POSSIBLE APPLICATIONS FOR REMOTE SENSING
 
Comparing size-fractionated chlorophyll concentration and phytoplankton absorption spectra for a wide variety of natural communities, we found, in agreement with Yentsch and Phinney (1989, L&O), that changes in phytoplankton community structure are related to changes in phytoplankton abundance. With some exceptions, larger size-classes are added incrementally to a background of smaller cells. By explicitly characterizing communities according to dominant cell size, we describe the influence of these changes on the spectral shape of the phytoplankton absorption coefficient (SSPAC) for the whole assemblage. It was found that, by specifying the cell size of the dominant organism (pico-, ultra-, nano- or microplankton), more than 80% of the variability in SSPAC could be explained. This is a result of the strong covariation of size of dominant organism and several factors controlling SSPAC, such as pigment packaging and composition. Because of that, phytoplankton absorption can be reproduced using two spectra representing SSPAC for small and big cells, one parameter specifying the relative contribution of each, and a magnitude. Residuals contain some taxonomic and physiological information. We test the applicability of this parameterization in an inverse model for retrieving inherent optical properties from ocean color.
 
Day: Thursday, Feb. 4
Time: 02:45 - 03:00pm
Location: Eldorado Hotel
 
Code: CS61TH0245E