Metacommunity Structure, Species Richness and Species Composition of Reef Fish Trophic Guilds Along an Extensive Latitudinal Gradient in the Tropics

Abstract

Aim Our goals were (1) to identify the metacommunity structure of the reef fish fauna as well as the structure of its constituent trophic guilds (invertivores, generalist carnivores, omnivores, herbivores, planktivores and piscivores); (2) to evaluate the extent to which metacommunity compartmentalization is associated with biogeographic phenomena (isolation by distance, habitat filtering, estuarine plumes): and (3) to identify whether the latent environmental gradient that structures the metacommunity is related to latitude. Location Coral reefs of the Brazilian Biogeographic Province (BBP). Time Period 1998–2022. Major Taxa Studied Reef fish. Methods We categorized the BBP into biogeographic regions defined by spatio‐environmental characteristics and analysed the distribution of fish species in 150 sites that included a variety of reef types (abiogenic, biogenic and island‐associated reefs). For the entire fauna, and for each of its constituent trophic guilds, we ordinated their site‐by‐species incidence matrix using reciprocal averaging. Thereafter, we evaluated coherence, species turnover and species boundary clumping to determine the structure of each metacommunity. To quantify whether latitudinal variation affects the latent environmental gradient that structures the metacommunity, we performed Spearman rank correlation analyses of site scores from reciprocal averaging. In addition, we used a suite of nested general additive models and hierarchical a priori analyses to explore the extent to which compositional differences between biogeographic regions contributed to the compartmentalization of metacommunities. Results In general, the metacommunity structure of the reef fish fauna is moulded by latitudinal correlates and exhibits compartmentalization (Clementsian and quasi‐Clementsian structure) with compositionally distinct compartments arising because of isolation by distance (island vs. continental reefs), habitat filtering (abiogenic vs. biogenic reefs), or the influence of estuarine plumes associated with the mouths of large rivers. Nonetheless, the number and identity of compartments differed among trophic guilds. Island and continental reefs were compositionally distinct for the entire fish fauna, as well as for invertivores and omnivores. Biogenic and abiogenic reefs were compositionally distinct for omnivores, herbivores and piscivores. Northern and eastern biogenic reefs were compositionally distinct for invertivores, omnivores and piscivores. Main Conclusions Degree of isolation (island versus continental reefs) and dispersal barriers (habitat types and estuarine plumes) likely interact to affect the pervasive compartmentalization of marine fish metacommunities in the BBP. The extent to which they operate is guild‐specific, suggesting that the nature of compartmentalization in the fauna is a composite of contributions by different guilds, especially those with high species richness.

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