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MEPS prepress abstract   -  DOI:

Environmental factors involved in manta rays` breaching behavior in estuarine waters

A. M. Medeiros*, C. Ari, E. L. A. Monteiro-Filho

*Corresponding author:

ABSTRACT: Improving our knowledge on the behavior of threatened species is essential to develop effective conservation actions. The Paranaguá Estuarine Complex (PEC), Southern Brazil, is the only estuary in the world where manta rays have been observed performing breaches seasonally. The exact role of the breaching behavior and the environmental factors connected to it are unknown. Our goals were to determine the spatial distribution, the temporal and environmental factors that influence the breaching behavior of this endangered group for the first time in a dynamic estuarine habitat. Manta rays were observed breaching in PEC during austral summer and early autumn, when the sea surface temperature (SST) and precipitation were high. The generalized additive models reveled that the presence and frequency of the breaches were both influenced by the SST and hours of daily effort, while the breaching frequency was also influenced by the wind direction and speed, percentage of moon illumination and year. The breaches were mainly concentrated near the mouth of a river. Likely these factors influenced not only their occurrence and behavior, but also the distribution of their food source, potentially providing optimal conditions for foraging and reproduction. Based on the coloration pattern, it is possible that the observations were of M. cf. birostris. These results provide valuable insight into the manta rays` breaching behavior in estuarine waters that will assist future conservation initiatives and research on the behavioral ecology, to optimize fishery management and contribute to developing sustainable ecotourism in PEC.