Article| Any: | 2016 |
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| Autor(s): | E. Schismenou, M. Palmer, M. Giannoulaki, I. Alvarez, K. Tsiaras, G. Triantafyllou, S. Somarakis |
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| Títol: | Seasonal changes in otolith increment width trajectories and the effect of temperature on the daily growth rate of young sardines |
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| Revista: | FISHERIES OCEANOGRAPHY |
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| ISSN: | 1054-6006 |
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| JCR Impact Factor: | 1.578 |
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| Volum: | 25 |
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| Número: | 4 |
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| Pàgines: | 362-372 |
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| D.O.I.: | 10.1111/fog.12158 |
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| Web: | http://onlinelibrary.wiley.com/doi/10.1111/fog.12158/abstract |
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| Resum: | We studied the otolith microstructure and growth of sardine, Sardina pilchardus,
in the North Aegean Sea (eastern Mediterranean Sea), using samples of
larvae and juveniles that had hatched in winter (November–January) and
winter–spring (February–May), respectively. The juveniles had developed
during an extended period coinciding with marked pelagic ecosystem
changes (from winter, mixed conditions to summer, stratified waters). To
examine the relationship between environmental changes and the observed
variability in their otolith increment–width trajectories
(width-at-age), we summarized the shape of trajectories with a
four-parameter set estimated from a growth model fit to each width
trajectory. The individual parameter sets were then related to the
potential oceanographic conditions that fish experienced during their
development, derived from a hydrodynamic–biogeochemical model
(POM-ERSEM), implemented in the sampling area. Substantial seasonal
effects were demonstrated on the otolith microstructure (platykurtic
versus leptokurtic trajectories in winter-mixed versus summer-stratified
conditions), which were related to the progressive sea surface warming.
In a subsequent step, in order to study the effect of oceanographic
conditions on larval and juvenile daily growth rates, a GAM (Generalized
Additive Model) analysis of otolith increment widths was carried out,
using model-derived oceanographic parameters and taking into account the
‘inherent otolith growth’, expressed by the explanatory variables
‘previous increment width’ and ‘Age’. Results showed a strong and
positive, linear effect of temperature on the growth rate of
winter-caught larvae, whereas in juveniles, which had developed within a
wide range of temperatures, an optimum temperature for growth was
observed at around 24°C. |
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