Year-round high abundances of the world’s smallest marine vertebrate (Schindleria) in the Red Sea and worldwide associations with lunar phases

AbstractVery little is known about the ecology and biology of the smallest marine vertebrates, fishes in the genus Schindleria. Even though over half of named Schindleria species have been identified in the Red Sea, the collection of only very few specimens has been documented. Here, we assessed abundance patterns of nearly two thousand Red Sea long dorsal fin (LDF) adults and found evidence for putative seasonal and spatial differences, likely related to differing habitat and environmental conditions. The highest abundances were outside local seasonal temperature extremes and decoupled from peaks of coral reef fish recruitment. We also found evidence for global trends in abundances related to lunar cycles using our Red Sea data and that from a recently published large collection of specimens from the DANA Expedition (1928–1930). The abundance of adult LDF Schindleria in relation to lunar phases differed significantly, with most Schindleria caught outside the full moon, and mostly during the new moon in the Red Sea and the 3rd quarter moon in the DANA collection. We further suggest that the abundances of Schindleria at coral reefs may be related to reproductive cycles and that these cycles may be timed with the moon as back-calculations of hatch dates from otoliths from the Red Sea significantly resulted after the new moon, making Schindleria the fastest-lived coral reef fish with the shortest generation times. Schindleria could be the most numerous coral reef fish in the world, for which we encourage increased research.

Robitzch, V., Molina-Valdivia, V., Solano-Iguaran, J. J., Landaeta, M. F., & Berumen, M. L. (2021). Year-round high abundances of the world’s smallest marine vertebrate (Schindleria) in the Red Sea and worldwide associations with lunar phases. Scientific Reports, 11(1). doi:10.1038/s41598-021-93800-w

For logistic and fieldwork support, we thank the Coastal and Marine Resources Core Laboratory at the King Abdullah University of Science and Technology (KAUST), as well as additional fieldwork volunteers. For help with otolith readings, we particularly thank Camilo Rodríguez-Valentino from the Laboratorio de Esclero-Cronología, Pontificia Universidad Católica de Valparaíso, Chile. This research was supported by KAUST baseline research funds to MLB and Xabier Irigoyen, and by the 2019 FONDECYT-CONICYT Postdoctoral fellowship N° 3190891 awarded to VR. This work is dedicated to the late J. E. Randall, who encouraged VR’s fascination for Schindleria when her first Red Sea specimens were identified.

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