Fig 1.
Studied areas at Rocas atoll, NE Brazil, indicating the different habitats.
The large scale map was plotted with the R software using the 'maptools' package [41] based on data provided by the GEOphysical DAta System—Next Generation (GEODAS-NG) of the NOAA (https://www.ngdc.noaa.gov/mgg/geodas/geodas.html). The illustration of the atoll was adapted from [39] but is not identical.
Fig 2.
Multidimensional Scaling (MDS) of the composition of reef fish assemblages among different habitats based on a Bray-Curtis similarity matrix.
Fig 3.
Density and biomass of reef fishes in open and closed pools at Rocas atoll.
Displayed species were chosen based on a ranking combining density and biomass. Error bars represent standard errors.
Fig 4.
Principal component analysis (PCA) on the composition of benthic cover of closed and open pools.
CCA—Crustose coralline algae.
Fig 5.
Mean percent cover of the main benthic groups (i.e. those that pooled comprise between 80 and 100% of total cover).
(*) Indicates significant differences between closed and open pools (t-test, p<0.05; S5 Table). Error bars represent the standard errors.
Fig 6.
Algal turf species composition and density of associated cryptofauna in open and closed pools.
(A) Mean biomass of the main turf-forming macroalgae; (B) mean density of cryptofauna associated to algal turfs; (C) correlation between cryptofauna density and algal turf biomass. The presented algal species combined account for 90% of total biomass in these habitats. Error bars represent the standard errors.
Fig 7.
Reef fish feeding pressure on the benthos in closed and open pools.
Colored bars indicate species functional groups. Error bars represent standard errors.
Fig 8.
Macroalgal removal and selectivity at the closed pool Tartarugas.
(A) Mean proportion of consumed algae biomass; (B) and (C) Mean number of bites on each macroalgae by the herbivorous fishes Acanthurus chirurgus and A. coeruleus, respectively; (D) Mean proportion of bites taken by the two herbivorous species on each algae; (E) Strauss linear selectivity index for the two herbivores on each algae. (*) indicates significant differences at a 5% significance level. In (A), (B), (C) and (D) error bars represent standard errors, and in (E) it represents the 95% confidence interval.
Fig 9.
Concentration of soluble sugars, starch, protein and lipid in the algae offered to herbivorous fishes.
Letters indicate significant differences according to an analysis of variance followed by a Tukey HSD test. N.A.—not available. Error bars represent standard errors.
Fig 10.
Diet of the two main roving herbivores at Rocas atoll: Acanthurus chirurgus and A. coeruleus.
Letters above bars indicate post-hoc comparisons of the Friedman test. Error bars represent standard errors.