S. Korpinen, V. Jormalainen, and T. Honkanen. 2007. Effects of nutrients, herbivory, and depth on the macroalgal community in the rocky sublittoral. Ecology 88:839–852.

Appendix B. Macroalgal diversity.

We calculated the Shannon-Wiener diversity (H’) according to Krebs (1989). In the statistical analysis, we used repeated measures ANOVA, date as a repeated factor, and nutrient enrichment, herbivory and depth as the between subject factors.

The macroalgal diversity showed high temporal variability that depended on both nutrient level and depth (depth × nutrient × date in Table B1, Fig. B1). This probably reflects the dynamic nature of the fast-growing ephemeral algae, their responses to nutrient enrichment and the depth-related differences in algal community and nutrient responses. The diversity along nutrient gradient depended on the growing depth so that at the ambient level diversity reached higher in shallow than deep water and the nutrient-enrichment enhanced the deep-water diversity (Table B1, Fig. B1). In general, the diversity was higher in shallow than deep water. Grazing did not have clear impact on the diversity, but the marginally significant depth × herbivory interaction suggests positive impact of grazing on the shallow-water assemblages (Table B1, Fig. B1).

LITERATURE CITED

Krebs, C. J. 1989. Ecological methodology. Harper and Row, Cambridge, UK.

TABLE B1. Statistical analysis of repeated measures ANOVA of macroalgal diversity (H’) across the four dates from July to November. The summary statistics are presented in Fig. B1.

FIG. B1. Macroalgal diversity (H’) in the shallow (a, c, e) and deep (b, d, f) water, in the three nutrient (no = a, b, low = c, d, and high = e, f), and herbivory treatments (circles = open, herbivory [OC], triangles = roofed herbivory [RC], and squares = closed, no herbivory [CC]). The values refer to least square means and SE’s of the model (see Statistical analyses).