Spectral resolution (full width at half maximum, FWHM) and corresponding sensors used to simulate new spectra and retrieve new a* and MPB_LUE values for estimating ETR.

<p>Slope and R² of linear regression between ETR estimated from fluorometry and radiometry are reported. All regressions are significant (p < 0.001), except ⁽¹⁾; ⁽²⁾ Future sensors; ⁽³⁾ Spectral sampling is indicated when different of the FWHM.</p

Measured ETR (from PAM fluorometry) <i>vs</i>. predicted ETR (from radiometric measurements using the MPB_LUE index).

<p>The dash line is the slope (= 0.93) of the linear regression (R² = 0.92, p<0.001). All species and growth forms were included: ●Epipelic (<i>Navicula phyllepta</i> and <i>Entomoneis paludosa</i>); ■Epipsammic (<i>Biremis lucens</i> and <i>Planothidium delicatulum</i>); ◆Tychoplanktonic (<i>Plagiogrammopsis vanheurckii</i>).</p

Pigment ratios relative to chlorophyll <i>a</i> of each strain, expressed in g.g^-1 Chl <i>a</i>.

<p>Values are the mean of ratios obtained at the end of each light exposure (from 0 to 1950 μmol photon.m^-2.s^-1) ± variation coefficient. Growth form is presented for each strain.</p

Typical radiometric spectra from <i>B</i>. <i>lucens</i> cultures exposed to three different light intensities.

<p>(5 min): 0 (black line), 665 (grey line) and 1950 (clear grey line) μmol photons.m^-2.s^-1. a/ Standardized reflectance; b/ Standardized second derivative. Arrows show absorption bands at 496, 540, 588, 632 and 673 nm respectively due to DD+DT, Fuco, Chl <i>a</i>, Chl <i>c</i> and again Chl <i>a</i> (see text and [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref029" target="_blank">29</a>]). The box delimits the absorption domain due to DD and DT xanthophylls (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.g005" target="_blank">Fig 5</a>).</p

Spectral indices calculated using second derivative value standardized to the Chl c red absorption band (<i>δδ</i>₆₃₂) and explaining more than 40% of the variability (R² > 0.4) of the LUE estimated by PAM-fluorometry using <i>Navicula phyllepta</i> (<i>N</i>. <i>phyl</i>) and <i>Biremis lucens</i> (<i>B</i>. <i>luce</i>) data set.

<p>The lowest values of RSME (= Root Mean Square Error), in bold, to predict LUE for <i>Entomoneis paludosa</i> (<i>E</i>. <i>palu</i>) <i>Planothidium delicatulum</i> (<i>P</i>. <i>deli</i>) and <i>Plagiogrammopsis vanheurckii</i> (<i>P</i>. <i>vanh</i>) are those selected (Eqs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.e008" target="_blank">8</a> to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.e013" target="_blank">13</a>). ***: linear regression p ≤ 0.001; n.t.: not tested.</p

Optical absorption cross-section a*.

<p>Retrieved from the MPBOM transfer radiative model [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref027" target="_blank">27</a>] and averaged over the Chl <i>a</i> absorption domain (670 to 685 nm) and for all species. Vertical bars represent standard deviation.</p

Spectra from <i>B</i>. <i>lucens</i> culture, after 5 min in the dark at different spectral resolutions.

<p>From the top (dark line) to the bottom (clear grey line): 1 nm (original data from ASD), 3.26 nm (HySpex simulation), 3.5 nm (CASI simulation), 6 nm (EnMap simulation), 10 nm (AVIRIS, Hyperion and HypXim simulation) and 15 nm (DAIS and HyMap simulation). Specific absorption features around 496, 540, 588, 632 and 673 nm respectively due to DD+DT, Fuco, Chl <i>a</i>, Chl <i>c</i> and again Chl <i>a</i> were still observable. Reflectance is presented in arbitrary unit (A.U) to avoid overlaying of spectra.</p

Zoom from Fig B for standardized second derivative over the absorption domain due to xanthophyll pigments involved in the XC (DD and DT) between 480 and 530 nm.

<p>Shoulders are assigned to absorption features of DD and DT from literature (DD¹: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref030" target="_blank">30</a>]; DT³: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref017" target="_blank">17</a>]; and DT⁴_NPQ: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref031" target="_blank">31</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref038" target="_blank">38</a>] and from this study (DD+DT²_LL, DD+DT² and DD+DT²_HL). For details see text.</p

DES <i>versus</i> light intensity after 5 min exposure for the three growth forms.

<p>●Epipelic (<i>Navicula phyllepta</i> and <i>Entomoneis paludosa</i>); ■Epipsammic (<i>Biremis lucens</i> and <i>Planothidium delicatulum</i>); ◆Tychoplanktonic (<i>Plagiogrammopsis vanheurckii</i>). Averaged DES were fitted using the model proposed by [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.ref037" target="_blank">37</a>], vertical bars represent standard deviation.</p

Spectral indices calculated using second derivative from DD-DT xanthophyll pigments absorption band (see Fig 5) and explaining more than 40% of the variability (R² > 0.4) of the LUE estimated by PAM-fluorometry using <i>Navicula phyllepta</i> (<i>N</i>. <i>phyl</i>) and <i>Biremis lucens</i> (<i>B</i>. <i>luce</i>) data set.

<p>The lowest values of RSME (= Root Mean Square Error), in bold, to predict LUE for <i>Entomoneis paludosa</i> (<i>E</i>. <i>palu</i>) <i>Planothidium delicatulum</i> (<i>P</i>. <i>deli</i>) and <i>Plagiogrammopsis vanheurckii</i> (<i>P</i>. <i>vanh</i>) are those selected (Eqs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.e008" target="_blank">8</a> to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197093#pone.0197093.e013" target="_blank">13</a>). ***: linear regression p ≤ 0.001; n.t.: not tested.</p