Comparison of isotopic turnover dynamics in two different muscles of a coral reef fish during the settlement phase

David Lecchini,Gilles Lepoint,Bruno Frédérich,Laura Gajdzik

doi:10.3989/scimar.04225.31a

Abstract

The temporal variation in carbon and nitrogen isotopic compositions (noted as δ13C and δ15N) was investigated in the convict surgeonfish (Acanthurus triostegus) at Moorea (French Polynesia). Over a period of 24 days, juveniles were reared in aquaria and subjected to two different feeding treatments: granules or algae. The dynamics of δ13C and δ15N in two muscles (the adductor mandibulae complex and the epaxial musculature) having different functions were compared. At the end of experiments, a steady-state isotopic system in each muscle tissue was not reached. Especially for the algal treatment, we found different patterns of variation in isotopic compositions over time between the two muscles. The turnovers of δ13C showed opposite trends for each muscle but differences are mitigated by starvation and by the metamorphosis. Our study highlighted that the metabolism of coral reef fish may be subjected to catabolism or anabolism of non-protein precursors at settlement, inducing variation in isotopic compositions that are not linked to diet change.

Highlights

The life cycle of the majority of reef fishes is a complex process that comprises two main distinct phases, a pelagic larval stage corresponding to long-distance migrations of larvae and a demersal stage that includes juveniles as well as adults (Leis 2002, Lecchini and Galzin 2003)
This study is the first one exploring the dynamics of carbon and nitrogen turnover from two different muscles during the first days of post-settlement in a coral reef fish
We found some different patterns of variation in isotopic compositions over time between muscles

Summary

Introduction

The life cycle of the majority of reef fishes is a complex process that comprises two main distinct phases, a pelagic larval stage corresponding to long-distance migrations of larvae and a demersal stage that includes juveniles as well as adults (Leis 2002, Lecchini and Galzin 2003). McCormick and Makey 1997, Lecchini 2005) This major event in the life history of reef fishes is generally called metamorphosis (McCormick and Makey 1997) and may correspond to rapid variations in internal stable isotope compositions (Herzka and Holt 2000). Comparing carbon and nitrogen isotopic compositions during that phase might provide information about physiology and tissue turnover

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