Vertical distribution of photopigments in a representative piece of the Um Alhool mat shown in true color image (A), using hyperspectral imaging and HPLC.

<p>Panel (B) represents the false color image of Chl <i>a</i> distribution calculated using MPBI. The color code ranges from blue (less Chl <i>a</i>) to red (high Chl <i>a</i>). Composite RGB image (C) shows distributions of Chl <i>a</i> (green channel), phycocyanin (PC; red channel) and bacteriochlorophyll <i>a</i> (BChl <i>a</i>; blue channel), as derived from hyperspectral imaging based on their characteristic spectral signatures (D). Scale bar is 1 cm. The lower panel shows the vertical distribution and the concentration (in μg m⁻³) of photopigments (Scytonemin, fucoxanthin, zeaxanthin, chl, and β-carotene) measured using HPLC (E), and the distribution of Bacteriochlorophyll (F) calculated as arbitrary units.