Age-related trends in otolith chemistry of Merluccius merluccius from the north-eastern Atlantic Ocean and the western Mediterranean Sea

Abstract

Sagittal otoliths of European hake obtained from five geographic locations in the north-eastern Atlantic and western Mediterranean were examined using laser ablation and inductively coupled plasma mass spectrometry. Otolith sections were analysed for the isotopes 24 Mg, 55 Mn, 66 Zn, 85 Rb, 86 Sr, 138 Ba and 208 Pb, measured relative to 43 Ca counts. These analyses considered only age 0 (core area) and ages 1 to 3. Age-related trends in otolith elemental composition were observed in hake from all areas, but were masked by variability between locations. Elemental concentrations generally decreased outside the core, with some increase at age 3. The composition of the otolith core was very distinct from that of the other growth increments. In the Mediterranean, part of this differentiation was a result of Mn, which was present in the core at high concentrations compared with the rest of the otolith. Mediterranean otoliths also had higher concentrations of Sr, Zn and Ba in the core. For most samples a similar trend was observed, although samples from one of the Mediterranean areas showed some differences, mainly in the concentrations of Mg and Sr. These results provide new empirical evidence of the variation in elemental concentrations across hake otoliths with age, at least throughout the first 3 years of life.

Interactive effects of ontogeny, food ration and temperature on elemental incorporation in otoliths of a coral reef fish

“…Few studies have experimentally validated ontogenetic effects on elemental incorporation, although several investigators have reported age-related changes in otolith composition in transects of wild caught fish. Ontogenetic variation in elemental concentrations has been observed in several species (e.g., Papadopoulou et al 1980;Kalish 1989;Hoff and Fuiman 1993;Fuiman and Hoff 1995;Morales-Nin et al 2005). Considerable evidence has also shown that distinct chemical changes accompany metamorphosis and settlement (e.g., Otake et al 1997;de Pontual et al 2003;Chen et al 2008;Sandin et al 2005).…”

Seasonal and ontogenic migrations of meagre (Argyrosomus regius) determined by otolith geochemical signatures

“…We were not able to make direct measurements of Sr concentrations in the areas likely to be inhabited by these meagre, but this area of Spain is known for its metal and mining activities, and natural strontium sources are abundant (Hanor, 2000;Cánovas et al, 2007). Physiological processes also affect otolith Sr:Ca ratios, especially those associated with metamorphosis, sexual maturation, and annual cycles of gonad maturation and spawning (Campana, 1999;Kalish, 1989Kalish, , 1991Morales-Nin et al, 2005). Metamorphosis can produce short-term increases in otolith Sr:Ca (Arai et al, 1997;de Pontual et al, 2003;Lin et al, 2011), but we were unlikely to observe these because our transects rarely included the inner portions of the first year's zone.…”

Large scale-variability in otolith microstructure and microchemistry: The case study ofDiplodus sargus sargus(Pisces: Sparidae) in the Mediterranean Sea

“…With regard to the otolith microchemistry, similarly, a few studies have been published in the Mediterranean Sea and mainly concerned pelagic species, such as Trachurus mediterraneus (Turan 2006) and Thunnus thynnus (Rooker et al 2008), or fish targeted by trawling such as Merluccius merluccius and Helicolenus dactylopterus (Morales-Nin et al 2005;Swan et al 2006). Only Gillanders et al (2001) carried out chemical analyses on otoliths of littoral species in the Mediterranean, such as Diplodus vulgaris along the Spanish coast, but integrated assays across the entire lifetime of fish by performing elemental analyses on whole dissolved otoliths (i.e.…”