Figure 3

SEM image of (A) Patchy distribution of the morphologically variable surface-associated microbiota (white box 1) with small surface areas not covered by the biofilm (orange boxes 2, 3, 4, magnification: 1000×), and (B) Cross-section showing algal epidermis cells covered by epibionts. 1. Microbial biofilm thickness was measured to be ca. 10–15 µm (magnification: 2000×). 2. Elongated epidermal cells partly filled with plastids. 3. Plastids in epidermal and sub-epidermal cells.