Table S3.

Results of the artifact control experiment testing the effects of peg density on each response variable in Masonboro Island NERR

Response variable	No. of pegs per m−2		df	F	P value	Adjusted R2
	0	16
Epifauna abundance, no. per m−2	46.50 ± 34.60	41.00 ± 24.63	14	0.13	0.72	−0.06
Epifauna richness, taxa per m−2	4.62 ± 1.09	4.00 ± 1.58	14	0.82	0.38	−0.01
Dissolution, mass lost in g d−1	8.27 ± 1.70	7.66 ± 1.72	14	0.51	0.49	−0.03
Decomposition, mass lost in g mo−1	0.98 ± 0.11	0.97 ± 0.16	13	0.01	0.92	−0.08
Infauna abundance, no. per L−1	66.21 ± 24.68	65.36 ± 28.33	14	0.00	0.95	−0.07
Infauna richness, taxa per L−1	4.51 ± 1.07	4.05 ± 1.10	14	0.69	0.42	−0.02
Number of ray holes, m−2 d−1	0.03 ± 0.02	0.03 ± 0.03	14	0.08	0.78	−0.07
Multifunctionality, %	0.55 ± 0.08	0.55 ± 0.15	13	0.01	0.91	−0.08

Pairs (n = 8) of 1-m² plots were established 1 m apart on an intertidal flat with low Gracilaria density. The distance between pairs was at least 5 m. Treatments of either 0 or 16 pegs m⁻² (corresponding to the highest peg density used in our experiment) were assigned at random within each pair of plots by flipping a coin. The experiment was maintained for 30 d, during which the responses were measured in each plot as described in the text. Data are presented as mean ± SD for each treatment, corresponding to the lowest (0 m⁻²) vs. highest (16 m⁻²) peg density used in our experiment. Results of one-way ANOVA are given on the right. Note that all P values were >0.35 and absolute values of R² were <0.1, documenting that the pegs used in our experiment to control the abundance of Gracilaria did not by themselves affect any response variables.