Additive Partitioning of Coral Reef Fish Diversity Across Hierarchical Spatial Scales Throughout the Caribbean

Francisco-Ramos V, Arias-González JE . 2013. Additive Partitioning of Coral Reef Fish Diversity Across Hierarchical Spatial Scales Throughout the Caribbean.

PLoS ONE. 8(10): e78761. doi:10.1371/journal.pone.0078761

There is an increasing need to examine regional patterns of diversity in coral-reef systems because their biodiversity is declining globally. The authors used REEF data from 80 sites from 6 eco-regions throughout the Caribbean to evaluate patterns of biodiversity. Specifically, they used "additive partitioning", which quantifies the contribution of different types of diversity (alpha and beta; comparing diversity between sites within a region and between regions) to total diversity across different spatial scales. 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. The author's results highlight the importance of ecoregions as a spatial scale to conserve local and regional coral reef-fish diversity.

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