TITLE:
Variability in the Light Absorption Coefficient by Phytoplankton, Non-Algal Particles and Colored Dissolved Organic Matter in the Northern Gulf of California
AUTHORS:
Stella P. Betancur-Turizo, Adriana G. González-Silvera, Eduardo Santamaría-Del-Ángel, Roberto Millán-Núñez, Eduardo Millán-Núñez, Héctor García-Nava, Víctor M. Godínez, Laura Sánchez-Velasco
KEYWORDS:
Light Absorption, Phytoplankton, CDOM, Detritus, Ocean Color, Gulf of California
JOURNAL NAME:
Open Journal of Marine Science,
Vol.8 No.1,
December
25,
2017
ABSTRACT: Variability of the optical properties of the northern Gulf of California (México)
were analyzed for the first time based on six cruises performed from
spring to summer (March to September) between 2008 and 2013. The changes
observed in the absorption by three seawater components (phytoplankton,
detritus and chromophoric dissolved organic matter or CDOM) were analyzed
in relation to changes in bio-optical regions and composition of the
phytoplankton community (determined based on phytoplankton pigments).
Two regions with unique bio-optical characteristics were identified separated
by a narrow transition zone: the Upper Gulf of California (UGC) and Northern
Gulf of California (NGC). Despite the temporal changes in their spatial
distribution they maintained particular characteristic. UGC is characterized
by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms
and dinoflagellates) and a stronger contribution of detritus to total light
absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the
predominance of picophytoplankton, characterized by the dominance of
zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker
pigment for green algae), along with a co-dominium by CDOM and phytoplankton
to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus
and CDOM to total light absorption what has to be considered for the
selection of bio-optical models for each specific region what can also help to a
better definition of the related uncertainties.