Additive Partitioning of Coral Reef Fish Diversity across Hierarchical Spatial Scales throughout the Caribbean

Abstract

There is an increasing need to examine regional patterns of diversity in coral-reef systems since their biodiversity is declining globally. In this sense, additive partitioning might be useful since it quantifies the contribution of alpha and beta to total diversity across different scales. We applied this approach using an unbalanced design across four hierarchical scales (80 sites, 22 subregions, six ecoregions, and the Caribbean basin). Reef-fish species were compiled from the Reef Environmental Education Foundation (REEF) database and distributions were confirmed with published data. Permutation tests were used to compare observed values to those expected by chance. The primary objective was to identify patterns of reef-fish diversity across multiple spatial scales under different scenarios, examining factors such as fisheries and demographic connectivity. Total diversity at the Caribbean scale was attributed to β-diversity (nearly 62% of the species), with the highest β-diversity at the site scale. α¯-diversity was higher than expected by chance in all scenarios and at all studied scales. This suggests that fish assemblages are more homogenous than expected, particularly at the ecoregion scale. Within each ecoregion, diversity was mainly attributed to alpha, except for the Southern ecoregion where there was a greater difference in species among sites. β-components were lower than expected in all ecoregions, indicating that fishes within each ecoregion are a subsample of the same species pool. The scenario involving the effects of fisheries showed a shift in dominance for β-diversity from regions to subregions, with no major changes to the diversity patterns. In contrast, demographic connectivity partially explained the diversity pattern. β-components were low within connectivity regions and higher than expected by chance when comparing between them. Our results highlight the importance of ecoregions as a spatial scale to conserve local and regional coral reef-fish diversity.

Spatial distribution of surgeonfish and parrotfish in the north sector of the Mesoamerican Barrier Reef System

“…However species richness did not seem to be regionally affected. This coincides with a recent study at the level of the Caribbean that found that fishing pressure is not important for structuring biodiversity distribution patterns (Francisco‐Ramos & Arias‐González ), although it may affect fish size and abundance, including surgeonfish and parrotfish, in the nsMBRS. Despite this, the low abundances and size structures found here appear to indicate that several environmental factors, not only fishing, are negatively influencing the grazing fish assemblages.…”

Partitioning scleractinian coral diversity across reef sites and regions in the Western Indian Ocean

“…). In contrast, Francisco‐Ramos and Arias‐González () investigation of Caribbean reef fishes found larger alpha and smaller beta‐diversity than expected by chance. The authors argued that this resulted from high demographic connectivity in the Caribbean.…”

Species‐specific environmental preferences associated with a hump‐shaped diversity/temperature relationship across tropical marine fish assemblages

“…A Census of Marine Life study of all Caribbean marine species found species richness to be higher in the Antilles and northern coast of South America, although sampling issues complicated interpretation of these patterns (Miloslavich et al., ). Francisco‐Ramos and Arias‐González () demonstrated that Caribbean marine fish assemblages tend to be more homogeneous than expected by chance and that local species richness (alpha diversity) is a major driver of overall diversity (i.e. gamma diversity) across the Caribbean basin.…”