Fig. 3

Trends in overall species richness (a, b) and diversity (c, d) along the vertical intertidal gradient at Nord-Ost Hafen and Kringel, respectively. At Nord-Ost Hafen, surveys were carried out at elevation zones 1 (between −10 cm and 20 cm of elevation relative to chart datum), 2 (20–50 cm), 3 (50–80 cm), 4 (80–110 cm), 5 (110–140 cm), 6 (140–170 cm), 7 (170–200 cm), 8 (200–230 cm), and 9 (230–260 cm). At Kringel, only elevation zones 1–6 were surveyed (see “Materials and Methods” for explanation). The quadratic function of best fit is shown for each relationship (see “Results” for statistics)