MEPS 550:191-206 (2016)  -  DOI:

Evaluating chemical signatures in a coastal upwelling region to reconstruct water mass associations of settlement-stage rockfishes

Sarah G. Wheeler1,*, Ann D. Russell2, Jennifer S. Fehrenbacher2, Steven G. Morgan3

1Graduate Group in Ecology at the University of California at Davis and San Diego State University, 5500 Campanile Dr, San Diego, California 92184-4614, USA
2University of California, Davis, One Shields Ave, Davis, California 95616, USA
3Bodega Marine Laboratory, University of California, Davis, 2099 Westside Dr, Bodega Bay, California 94923-0247, USA
*Corresponding author:

ABSTRACT:  Characterizing the behavior of larvae prior to settlement is integral to understanding population dynamics because coastal oceanography may facilitate or limit settlement. Otolith microchemistry can be used to determine patterns of fish movement, although there is a limited understanding of how this tool can be applied in coastal marine systems. Our goal in this study was to evaluate the application of otolith microchemistry to characterize water mass associations of settlement-stage marine fish in a coastal upwelling region using a 3-step approach. First, we characterized seawater chemistry of coastal water mass types across multiple years, finding differences in the chemical signatures of strong upwelling, weak upwelling, and relaxation events. Second, we experimentally determined the effect of temperature on the partitioning of trace elements in otoliths for 2 rockfishes (Sebastes spp.) to find that the effect of temperature on otolith partition coefficients was element- and species-specific. Finally, we compared coeval changes in seawater and otolith chemistry of settlement-stage rockfishes that were exposed to naturally variable conditions over an upwelling-relaxation cycle. We subsequently evaluate whether laser ablation inductively coupled plasma mass spectrometry effectively measures otolith chemistry over ecologically relevant time scales. We discovered that elemental concentrations in otoliths respond rapidly to changes in seawater chemistry and reflect equivalent proportional changes. This study provides evidence that elemental signatures are valuable tools for reconstructing larval histories of marine fish in coastal upwelling regions.

KEY WORDS:  Barium · Laser ablation · Inductively coupled plasma mass spectrometry · ICP-MS · Otolith · Seawater

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Cite this article as: Wheeler SG, Russell AD, Fehrenbacher JS, Morgan SG (2016) Evaluating chemical signatures in a coastal upwelling region to reconstruct water mass associations of settlement-stage rockfishes. Mar Ecol Prog Ser 550:191-206.

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