Multi-element otolith fingerprints unravel sea−lagoon lifetime migrations of gilthead sea bream Sparus aurata

L Mercier,D Mouillot,O Bruguier,L Vigliola,Am Darnaude

doi:10.3354/meps09444

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 444:175-194 (2012) - DOI: https://doi.org/10.3354/meps09444 Multi-element otolith fingerprints unravel sea−lagoon lifetime migrations of gilthead sea bream Sparus aurata Lény Mercier1, David Mouillot1, Olivier Bruguier2, Laurent Vigliola3, Audrey M. Darnaude1,* 1ECOSYM, UMR 5119, Université Montpellier 2, Place Eugène Bataillon 34095, Montpellier Cedex 5, France 2Géosciences Montpellier, UMR 5243, Université Montpellier 2, Place Eugène Bataillon 34095, Montpellier Cedex 5, France 3IRD, UR 227 CoReUs, Centre IRD de Nouméa, BP A5, 98848 Nouméa, New Caledonia *Email: audrey.darnaude@univ-montp2.fr ABSTRACT: Precise knowledge of lifetime migrations is vital in exploited fish species, since all essential habitats must be protected to maintain sustainable stock levels. The present study used multi-element otolith fingerprints of the gilthead sea bream Sparus aurata (L.) to discriminate its main juvenile and adult habitats in the Languedoc-Roussillon region (Gulf of Lions, northwest Mediterranean) and infer the lifetime migrations of 12 individuals from the area (11 from the present day and 1 from the Roman era). This allowed for the first time the identification of key habitats for the successful completion of the species’ life cycle in the Gulf of Lions, and the connectivity between them. Our results revealed that lagoon use by S. aurata is probably ancient (>2500 yr) and confirmed its current commonness. Yet, although most observed migration patterns were in accordance with the migratory behavior previously described for the species, strong inter-individual variations and new patterns in habitat use were detected. At the juvenile stage, a preference for shallow lagoons with low salinities was evidenced. Nevertheless, the first year of life can also be successfully completed in marine conditions. At the adult stage, lagoon use was shown to occur until at least age 4 yr, with periods of lagoon residency of up to 11 mo in a year, often including winter months. Because overwintering in the lagoons was previously thought to be impossible for S. aurata due to low temperatures, this finding has important implications for future stock management, especially since the species breeds in winter. KEY WORDS: Otolith microchemistry · Trace elements · Random forest · Key habitats · Gulf of Lions Full text in pdf format PreviousNextCite this article as: Mercier L, Mouillot D, Bruguier O, Vigliola L, Darnaude AM (2012) Multi-element otolith fingerprints unravel sea−lagoon lifetime migrations of gilthead sea bream Sparus aurata. Mar Ecol Prog Ser 444:175-194. https://doi.org/10.3354/meps09444 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 444. Online publication date: January 10, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Highlights

Conservation of marine fish resources requires reliable understanding of their lifetime migration patterns, because identification of natal sources, juvenile nursery grounds, and migration routes are key elements of population ecology and sustainable fisheries management (Forrester & Swearer 2002)
We developed pluri-annual and multi-elemental otolith fingerprints from the 4 main coastal habitats used by S. aurata in the Gulf of Lions (3 contrasted lagoons and the sea) to infer lifetime sea-lagoon migrations in the species from the signatures in the otoliths of 11 present-day adults, plus an archeological otolith dated from the Roman era (~475 yr BC)
The use of random forest (RF) allows the extracting of signals from multi-element otolith fingerprints from different years and life stages and building a robust classifier for identification of fish coastal habitats, irrespective of fish age and capture date

Summary

Introduction

Conservation of marine fish resources requires reliable understanding of their lifetime migration patterns, because identification of natal sources, juvenile nursery grounds, and migration routes are key elements of population ecology and sustainable fisheries management (Forrester & Swearer 2002). As anthropogenic pressure on the littoral zone intensifies, coastal ecosystems are increasingly threatened by pollution, eutrophication, and habitat degradation (Nixon 1995, Kemp et al 2005), resulting in habitat loss, population fragmentation, and erosion of biodiversity (Levin et al 2001) In this context, understanding and measuring connectivity among coastal habitats used by young and adult fish is essential to define marine protected areas (Mumby et al 2011), Mar Ecol Prog Ser 444: 175–194, 2012 and quotas for recreational and commercial fisheries (Gillanders et al 2003). Large numbers of post-larvae enter coastal lagoons (Audouin 1962), where they feed over the summer before migrating back offshore in autumn, when water temperature in the lagoons drops below that of the open sea (Lasserre 1976)

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Discussion

Conclusion