Light Absorption by Suspended Particles in the Red Sea: Effect of Phytoplankton Community Size Structure and Pigment Composition
KAUST DepartmentRed Sea Research Center (RSRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Marine Science Program
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AbstractThe light absorption properties of phytoplankton (aph(λ)) and non-algal particles (anap(λ)) associated with phytoplankton pigments were analyzed across the Red Sea, in the upper 200 m depth, between October 2014 and August 2016. The contribution by non-algal particles to the total particulate light absorption (aph(λ)+ anap(λ)) was highly variable (23 ± 17% at 440 nm) and no relationship between anap(440) and chlorophyll a concentration, [TChl a], was observed. Phytoplankton specific phytoplankton absorption coefficients at 440 and 676 nm for a given [TChl a], aph*(440) and aph*(676), were slightly higher than those derived from average relationships for open ocean waters within the surface layer as well as along the water column. Variations in the concentration of photosynthetic and photoprotective pigments were noticeable by changes in phytoplankton community size structure as well as in aph*(λ). This study revealed that a higher proportion of picophytoplankton and an increase in photoprotective pigments (mainly driven by zeaxanthin) tended to be responsible for the higher aph*(λ) values found in the Red Sea as compared to other oligotrophic regions with similar [TChl a]. Understanding this variability across the Red Sea may help improve the accuracy of biogeochemical parameters, such as [TChl a], derived from in situ measurements and ocean color remote sensing at a regional scale.
CitationKheireddine M, Ouhssain M, Organelli E, Bricaud A, Jones BH (2018) Light Absorption by Suspended Particles in the Red Sea: Effect of Phytoplankton Community Size Structure and Pigment Composition. Journal of Geophysical Research: Oceans. Available: http://dx.doi.org/10.1002/2017jc013279.
SponsorsThe authors express their gratitude to the scientists, officers and crews of the research vessel Thuwal and also the Coastal and Marine Resources Core Lab for logistical support and assistance onboard during the fieldwork. U. Langner is cordially thanked for plotting the map of the Red Sea, L. Solabarrieta and J. Otoadese for their advices and discussions on the results presented here and for reading the manuscript. Alison Chase and the anonymous reviewer are warmly thanked for the constructive comments on a previous version of the manuscript. This study is funded by the King Abdullah University of Science and Technology (KAUST), Kingdom of Saudi Arabia. The data presented in this study are available from the authors upon request (firstname.lastname@example.org) and are also archived in https://drive.google.com/open?id=0ByAL0hQpcGGPZmItRzh4eXNVdkk.