Phenotypic variations in the preferred host coral impact the occupancy of an obligate coral-dwelling fish
Habitat specialists form tight relationships with their host habitat and are able to make microscale decisions when selecting final habitat locations. The obligate coral-dwelling fish, Gobiodon histrio, is thought to make habitat choices based on the coloration and structural characteristics of Acropora nasuta, their preferred coral host. Yet, most studies on the habitat preference of G. histrio have been conducted on Australia’s Great Barrier Reef with no understanding if geographic differences in preferences exist. Here, we tested the habitat preference of G. histrio toward A. nasuta on the reefs of Kadavu and Tavewa Islands, Fiji. First, to assess the natural distribution, belt transect surveys of all acroporid corals were conducted. Transects indicated that, while G. histrio is most frequently found in A. nasuta over other acroporid corals, the coral’s structural characteristics rather than the coral’s color variation were the preferred characteristic. In contrast, the Australian G. histrio have been found to be more frequent in blue A. nasuta opposed to the brown color variation, suggesting a geographic difference in habitat preferences among the species. In addition, we conducted two in situ behavioral field experiments to determine whether G. histrio would (1) move from dead A. nasuta to a live brown or blue A. nasuta and (2) preferentially select between the brown- or blue-colored A. nasuta when placed on a dead A. nasuta. The results of the in situ experiments support the finding that Fijian G. histrio does not discriminate between A. nasuta using color but uses only structural morphologies to guide its habitat selection process. Habitat selection is a complex process, and microscale habitat preferences within a species can vary between geographic locations. This study sheds light on the need to expand research findings to incorporate large geographic regions when attempting to understand the preferences of coral reef symbionts.
KeywordsGobiodon histrio Habitat selection Acropora Coral goby Color polymorphism Fiji
Special thanks to E Ruhl, R Brooker, and M Ashur for assistance with fieldwork. Thanks to M Ashur, T Deemer, L Johnston, J Joseph, A Ostroski, and E Ruhl for assistance with editing this manuscript. Also, thanks to the staff at Coralview Island Resort on Tavewa Island and at Matava Resort on Kadavu Island. This research was funded by NIH U01-TW007401 (Dixson) and the Alfred P. Sloan Foundation (Dixson). This research was conducted under ethics approval number 1312 and followed all guidelines for the country in which it took place. Datasets used in this study are available online from the Zenodo repository ( https://doi.org/10.5281/zenodo.1477583).
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
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