Habitat use by herbivorous fish and sea turtles using acoustic telemetry

Cesar Cordeiro¹, Bruna Palese¹, Carlos Eduardo Ferreira², Moyses Barbosa², Marcos Lucena²

¹Universidade Estadual do Norte Fluminense, Brasil - ²Universidade Federal Fluminense, Brasil

Rocky reefs provide complex and essential habitats for several species, including highly mobile herbivores, which play crucial roles in reef dynamics by controlling algal growth and influencing the structure of the benthic community. The present study aimed to identify the habitat use patterns of taxa from two functional groups of herbivores: the surgeonfish Acanthurus chirurgus and the green turtle (Chelonia mydas). We focused on the distribution, residence time, and site fidelity using passive acoustic telemetry techniques. For the study, we installed nine receivers on rocky reefs of Arraial do Cabo Marine Extractive Reserve in Rio de Janeiro (Brazil). Twenty-five surgeonfish and 18 green turtles were tagged with acoustic transmitters, and monitoring was carried out between January and July 2024. The results indicated a variation in the daily movement range among surgeonfish (200 to 6000m), with some individuals exhibiting territorial behavior and others demonstrating greater mobility. The analysis of residence indices revealed significant fidelity to some habitats, while others moved across wider areas, probably searching for food resources (RI = 0.3 to 0.8). Green turtles showed high detection frequency and consistent residence patterns (RI = 0.65 to 0.95). Arraial do Cabo has one of the highest densities of C. mydas globally, reinforcing these areas’ ecological importance as foraging ground, sheltering, and resting sites. These results highlight that small-scale evaluations of habitat use of species with similar functional roles may reflect differences in ecological service delivery and the necessity of differences in conservation approaches.