Abstract

The diel cycle is one of the key environmental factors that drives reef fish activity patterns and spatial occupation. Diel movements and habitat shifts within coral reef seascapes are often related to foraging and anti-predator strategies. Many reef fishes display greater movement distances during foraging periods and more limited movements while resting or sheltering from predators. For most reef fish species, activity patterns tend to be either diurnal, nocturnal, or crepuscular. However, intra-specific variability in diel patterns may be driven by many factors including ontogeny, changes in environmental conditions and biological factors such as predation risk, foraging, and competition (Rooker et al. 2018). In the present study, we used acoustic telemetry to investigate the diel variability in the activity patterns of two poorly known endemic Brazilian reef fish species, the gray parrotfish Sparisoma axillare (Labridae) and the Brazilian snapper Lutjanus alexandrei (Lutjanidae). Both S. axillare and L. alexandrei are important resources for the artisanal fisheries in Northeast Brazil and appear to display activity patterns similar to congeners from each family, with contrasting diurnal and nocturnal foraging patterns, respectively. The study was conducted within a no-take zone, where positive effects of protection such as the increase in fish size and density have been reported for both species (Lippi et al. 2022). The knowledge on species diel patterns may have important implications for management and conservation of species and ecosystems, including the design of marine protected areas and marine spatial planning.

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