Oceanographic and lunar forcing affects nearshore larval fish assemblages from temperate rocky reefs

ABSTRACT

The influence of oceanographic features and moon phases on ichthyoplankton assemblages in a temperate nearshore rocky reef off El Quisco Bay, central Chile, was assessed during austral spring–summer 2015–2016 using Bongo nets. Wind direction was predominantly south-west, and ocean temperature increased gradually during the study period, fluctuating between 11.6°C and 17.7°C. A relatively cold period (from late September to early December, 12.42 ± 0.64°C) was distinguished from a relatively warmer phase (from mid-December to February, 13.56 ± 1.08°C). Nearshore ichthyoplankton was composed of 13,700 individuals, belonging to 43 taxa. Larval Strangomera bentincki (Clupeidae) were collected in high numbers between late September and late October with peaks during full moon and first quarter (maximum = 734 ind. 100 m⁻³); larval Engraulis ringens (Engraulidae) was most abundant between late October and late December 2015, with peaks during the third quarter and full moon. Principal Component Analysis of ichthyoplankton data explained more than 44% of total variance and showed the influence of cold/warm periods in the structuring of larval fish assemblages. Water temperature had more influence than lunar phase in the structure and composition of nearshore fish larvae off central Chile. We conclude that larval fish assemblages found in nearshore waters change on a seasonal scale by differences in the reproductive activity among species, and that lunar phase exerts a low, but significant effect on the abundance of fish larvae, but this variability is species-specific.

RESPONSIBLE EDITOR:

• Eric Hilton

KEYWORDS:

• Lunar cycle
• temperature
• fish larvae
• nearshore
• Chile

Acknowledgements

We want to thank all the field and lab work of Gissella Castillo-Hidalgo, Valentina Bernal-Durán, Francisca Zavala-Muñoz, Javier Vera-Duarte, Pilar Núñez, Bastián Fernandez, Antonia Reculé, Mirna Castillo, Cristian Ossess, Nicolás Pérez, Jorge E. Contreras and David Ortíz-González. We also thank Dr Randy Finke (Pontificia Universidad Católica de Chile) for providing the meteorological data used in this study. We appreciate the comments and suggestions of Dr Jeff Leis (University of Tasmania) and two anonymous referees to an earlier version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by Comisión Nacional de Investigación Científica y Tecnológica, CONICYT-Chile (grant number Fondecyt 1150296, adjudicated to MFL).