Figures and data in Global gradients in intertidal species richness and functional groups

Figures
Tables
Additional files

5 figures, 2 tables and 2 additional files

Figures

Figure 1

Download asset Open asset

Locations of rocky intertidal sampling sites.

Some sites are not visible because of close proximity. Functional diversity data were available in green sites.

Figure 2

Download asset Open asset

Latitudinal patterns in rocky intertidal α-diversity plotted against latitude.

Data are split into southern and northern hemispheres. A linear regression line (southern hemisphere) and a best-fit locally weighted scatterplot smoother (northern hemisphere) was added with 95% confidence intervals to aid visual interpretation.

Figure 3

Download asset Open asset

Local-scale relationships between (a) salinity, (b) wave exposure, (c) ice scour, and (d) macroalgal canopy cover on α-diversity.

A best-fit locally weighted scatterplot smoother (LOESS) and 95% confidence intervals (panel b) and boxplots (panels **c,d**) has been added to aid visual interpretation.

Figure 4

Download asset Open asset

Local-scale mean effect sizes and direction of ice scour, macroalgal cover, and salinity on α-diversity estimated from individual models.

Significance of regression parameters is identified as bootstrapped 95% confidence intervals (error bars) not crossing zero (* indicates significance).

Figure 5

Download asset Open asset

Latitudinal variation in the relative number of species from four functional groups in the rocky intertidal between 74.8°S and 80.5°N, where negative values denote southern hemisphere latitudes.

No data were available within the 5° latitudinal bands where bars are missing.

Tables

Table 1

Results of the mixed effect models for rocky intertidal α-diversity.

The estimate, standard error (SE), z-value, and p-value are presented for each variable. The estimated degree of freedom (ed), and p-value are presented for the smoother in the northern hemisphere*.

	Estimates	SE	z-Value	p-Value
Northern hemisphere
(Intercept)	3.086	0.283	10.92	<0.001
Chlorophyll a	−0.004	0.088	0.05	0.959
Phosphate	−0.163	0.288	−0.56	0.573
Sea temperature	0.024	0.015	1.64	0.101
Southern hemisphere
(Intercept)	3.199	0.443	7.225	<0.001
Latitude	0.006	0.007	0.899	0.369
Chlorophyll a	−0.006	0.007	−0.829	0.407
Phosphate	−0.240	0.234	−1.029	0.303
Sea temperature	−0.010	0.016	−0.653	0.514

*Approximate significance of cubic spline regression smoother: Estimated df = 2.005, p-value=0.023.

Table 2

Local-scale model summaries with individual models indicated for each model.

Estimated parameters, standard error (SE), bootstrapped 95% confidence intervals (95% CI), z-values, and p-values are reported for the relationship between α-diversity and environmental covariates.

Salinity R² = 0.19 (GLM)
	Estimates	SE	95% CI	z-Value	p-Value
(Intercept)	−3.201	0.891	−4.94; −1.47	−3.6	<0.0001
Salinity	6.676	0.946	4.82; 8.52	7.06	<0.0001
Wave exposure (GAM) R² = 0.12
	Estimates	SE		z-Value	p-Value
(Intercept)*	2.435	0.029		82.4	<0.0001
Ice scour (GLM) R² = 0.05
	Estimates	SE	95% CI	z-Value	p-Value
(Intercept)	2.353	0.055	2.24; 2.46	42.7	<0.0001
Ice scour	−0.401	0.087	−0.57; −0.23	−4.59	<0.0001
Macroalgal cover (GLM) R² = 0.14
	Estimates	SE	95% CI	z-Value	p-Value
(Intercept)	6.133	0.386	5.37; 6.89	15.9	<0.0001
Cover	−2.35	0.547	−3.42; −1.28	−4.3	<0.0001