Coral reefs harbor some of the highest levels of marine biodiversity despite occupying less than 0.2% of the ocean’s surface. Among reef-building corals, members of Pocilloporidae serve as key habitat-forming taxa supporting diverse symbiotic macro- and meiofaunal invertebrate assemblages, yet global patterns of symbiont diversity and host specificity remain poorly understood.
To address this gap, we compiled a global dataset of 3,078 occurrence records from 120 published studies spanning the entire documented history of research on pocilloporid symbionts, and standardized taxonomic, ecological, and host–symbiont metadata, yielding 1,003 FATUs (Finest Available Taxonomic Units) representing symbiotic invertebrates across 11 phyla and 315 families. This dataset represents the most comprehensive synthesis to date of invertebrate symbionts associated with Pocilloporidae and includes both macrofaunal and meiofaunal taxa, although published records remain strongly biased toward macrofauna.
Multivariate and null-model analyses identified host genus as a major predictor of symbiont community composition across marine realms, revealing strong host specificity and non-random phylogenetic structuring of host use. Bootstrap-based screening of well-sampled host–symbiont associations further confirmed the robustness of these patterns against uneven sampling effort.
Coverage-standardized diversity analyses revealed pronounced biogeographic structuring of symbiont diversity. Richness, Shannon, and Simpson indices consistently showed significant differences among marine realms, with the Western Indo-Pacific supporting the highest symbiont diversity.
These results demonstrate that both host filtering and large-scale biogeographic processes strongly shape coral-associated symbiont communities. By integrating macroecological, phylogenetic, and host-association data, this study establishes a robust baseline for long-term monitoring of temporal shifts in coral symbiotic communities and provides an analytical framework for assessing changes in reef biodiversity and resilience under ongoing environmental change.