Inferring phytoplankton carbon and eco-physiological rates from diel cycles of spectral particulate beam-attenuation coefficient

Abstract

Abstract. The diurnal fluctuations in solar irradiance impose a fundamental frequency on ocean biogeochemistry. Observations of the ocean carbon cycle at these frequencies are rare, but could be considerably expanded by measuring and interpreting the inherent optical properties. A method is presented to analyze diel cycles in particulate beam-attenuation coefficient (c p ) measured at multiple wavelengths. The method is based on fitting observations with a size-structured population model coupled to an optical model to infer the particle size distribution and physiologically relevant parameters of the cells responsible for the measured diel cycle in c p . Results show that the information related to size and contained in the spectral data can be exploited to independently estimate growth and loss rates during the day and night. In addition, the model can characterize the population of particles affecting the diel variability in c p . Application of this method to spectral c p measured at a station in the oligotrophic Mediterranean Sea suggests that most of Correspondence to: G. Dall'Olmo (gdal@pml.ac.uk) the observed variations in c p can be ascribed to a synchronized population of cells with an equivalent spherical diameter around 4.6±1.5 µm. The inferred carbon biomass of these cells was about 5.2-6.0 mg m −3 and accounted for approximately 10 % of the total particulate organic carbon. If successfully validated, this method may improve our in situ estimates of primary productivity.

Using Bio-Optics to Reveal Phytoplankton Physiology from a Wirewalker Autonomous Platform

“…The depth-resolved time series of POC cp reveals a minimum at dawn and a maximum at dusk, reflecting losses at night, and growth + losses (A in Figure 2d) during the day. This finding is consistent with other studies that have observed diel cycles in c p or dissolved oxygen concentration within the euphotic zone from moorings (Stramska and Dickey, 1992) and floats (Claustre et al, 1999;Dall'Olmo et al, 2011).…”

A multi-method autonomous assessment of primary productivity and export efficiency in the springtime North Atlantic

“…All data presented in this paper have been submitted to the Biological and Chemical Oceanography Data Management Office (BCO-DMO) and can be accessed from the "North Atlantic Bloom Experiment 2008" project page at https://www. bco-dmo.org/project/2098 (D'Asaro et al, 2018).…”

Influence of light in the mixed-layer on the parameters of a three-component model of phytoplankton size class

“…Fraction of Nanoplankton (cells 2-20 μm) Vidussi et al (2001) and Uitz et al (2006) attributed the diagnostic pigments 19′-hexanoyloxyfucoxanthin, 19′-butanoyloxyfucoxanthin (Goericke, 1995(Goericke, , 2002; B denotes data from the GeP&CO programme (Dandonneau et al, 2004); C denotes data from the BEAGLE cruise (Barlow et al, 2007); D denotes data from the BIOSOPE cruise (Bricaud, Babin, Claustre, Ras, & Tièche, 2010;Ras, Claustre, & Uitz, 2008); E denotes data from a Line-P cruise in the Subarctic Northeast Pacific (Werdell et al, 2003;Westberry, Dall'Olmo, Behrenfeld, & Moutin, 2010); F denotes data from a cruise in the Mediterranean Sea (Dall'Olmo et al, 2011;Werdell et al, 2003;Westberry et al, 2010); G denotes data from a cruise in the North Atlantic (Werdell et al, 2003;Westberry et al, 2010); H denotes data from a cruise in the Equatorial Pacific (Dall'Olmo, Westberry, Behrenfeld, Boss, & Slade, 2009;Werdell et al, 2003); I denotes data from the eastern Atlantic Ocean (Brotas et al, 2013); J denotes data from the Atlantic Meridional Transect cruises 1-22 (Aiken et al, 2009;Airs & Martinez-Vicente, 2014a, 2014b, 2014cBarlow et al, 2002;Gibb et al, 2000); K denotes data from the Agulhas ecosystem and Tanzania (Barlow, Kyewalyanga, Sessions, van den Berg, & Morris, 2008;Barlow et al, 2011); L denotes data from the Mozambique Channel (Barlow, Lamont, Morris, Sessions, & van den Berg, 2014); M denotes data gathered from various locations by the Bedford Institute of Oceanography (Devred et al, 2006;Sathyendranath et al, 2001); N denotes USJGOFS data in the Equatorial Pacific (Bidigare, 1994(Bidigare, , 1996; O denotes USJGOFS data from the Southern Ocean (RR_KIW) …”