Photo credit: JP Krajewski

How are reef fish packed? The influence of regional richness


Great advances have emerged on the relationships between alpha and gamma diversity for sessile reef-building corals. However, relatively little is known on how such relationships interplay for reef fish (mobile animals) communities. We addressed this gap compiling one the most biogeographically comprehensive reef fish community datasets – visual censuses through area-standardized strip transects (20x2m=40m2) between 0 and 30m deep in tropical rocky and coral reef systems (n=5.916 transects). The geographical range encompassed 103 sites spread through 17 major localities embedded in 6 main tropical biogeographical provinces: Caribbean, SW Atlantic, Tropical Eastern Atlantic and Pacific and South Pacific. Moreover, in addition to the classical taxonomic multi-scale approach (transect-site, site-locality, locality-region) we also present a functional richness packing perspective – functional groups per unit area. Local vs. regional plots, both taxonomic and functional, show that local community is positively enriched as regional richness increases, with no sign of approaching a saturation level. This indicates a strong influence of regional processes on the local composition of communities. Up-scaling analyses indicate that as one moves to richer biogeographic regions beta-diversity becomes increasingly important. We have also observed, on a global basis, an increase of both taxonomic and functional packing upon increasing coral regional richness. These results may indicate that diversity begets diversity in terms of habitat heterogeneity, i.e. niche diversification; however, both corals and fish’s evolution might have been driven by common factors. We show the importance of multi-scale and cross-ocean macroecological analyses for the understanding of underpinning processes of local biodiversity functioning.

Cairns, Australia

The slides for this talk can be found here