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Congeneric, sympatric tropical mullets respond differently to environmental variability: insights into coexistence

Jordana Rangely, Matheus Barros , Daniele Souto , Maria Oliveira, Victor da Silva, Ivan de Assis , Nidia Fabre

Abstract

Context: Disentangling mechanisms influencing the seasonal and spatial distribution of fish is essential to understanding population dynamics. In the Southwestern Atlantic, the sympatric mullets Mugil curema and M. rubrioculus are closely related and use habitat similarly. However, which processes allows their coexistence is unknown. Aim: We tested the hypothesis that the species exhibit different habitat use patterns that are temporally decoupled to allow sympatry due to different responses to environmental drivers. Methods: Bayesian zero-inflated models were used to unravel spatial and temporal distribution patterns of those species in a Southwestern Atlantic lagoon. Key results: The two species display different distribution within the estuary, being spatially and temporally segregated, with M. curema mostly inhabiting inner portions and M. rubrioculus inhabiting the outer estuary. Conclusions: This decoupling in habitat use might be driven by distinct responses to environmental variability: M. curema is influenced by factors such as temperature and dissolved oxygen, while M. rubrioculus by variations in salinity. We suggest that the studied species evolved divergent responses to environmental variation to allow coexistence. Implications: This study suggests that environmental factors drive the abundance of mullets inside estuaries, and are therefore useful in predicting their spatial and temporal distribution.

MF23108  Accepted 18 April 2024

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