Oxygen and carbon stable isotopes in the otoliths of wild and laboratory-reared Australian salmon (Arripis trutta)

Abstract

Australian salmon, Arripis trutta, collected from the east coast of Tasmania, Australia, in 1987, were weighed and measured and their otoliths marked by immersing fish in an oxytetracycline hydrochloride/seawater solution before placement in constant-temperature aquaria. Individual somatic and otolith growth rates were determined for input into mass balance models. Mass balance models were used to determine the oxygen and carbon isotopic composition of otolith material produced during captivity. There was a significant relationship between filsO measured in the otolith aragonite and ambient temperature (r 2 = 0.77). The linear relationship between these data, where 6180 = 6.69 -0.326 (T, °C), was not significantly different from a relationship indicative of equilibrium deposition of oxygen isotopes in aragonite. Otolith carbon was significantly depleted in 13C relative to equilibrium deposition, with depletions > 6.0%o at all temperatures. There was no relationship between 6~3C and temperature. It was estimated that > 30% of the otolith carbon was from metabolically derived sources. Significant differences in otolith carbon isotopes among wild juvenile Australian salmon were hypothesised to be attributable to differences in diet. Levels of variability for both oxygen and carbon isotopes in laboratory-maintained and wild fish were similar to that found by other researchers for foraminifera and these results highlight the importance of large sample sizes when estimating environmental temperatures from oxygen isotopes measured in fish otoliths.

Environmental influences on the recruitment process inferred from otolith stable isotopes in Merluccius merluccius off the Balearic Islands

“…However, our estimated values of δ c -δ w are consistent with previous studies on different fish species carried out in laboratory conditions (Kalish 1991b, Thorrold et al 1997, Gao et al 2001, Høie et al 2004b). All those investigations concluded that deposition occurs at or near equilibrium in fish otoliths.…”

Chemistry and composition of fish otoliths:pathways, mechanisms and applications

“…In otoliths, stable isotope ratios have been used to reconstruct temperature history (Devereux 1967. Mulcahy et al 1979, Kalish 1991b. Patterson et al 1993, Thorrold et al 1997b, differentiate among groups of fish (Edmonds & Fletcher 1997, Kennedy et al 1997, Dufour et al 1998, Thorrold et al 1998b, infer metabolic history , Kalish 1991c, Gauldie 1996a, Schwarcz et al 1998, and reconstruct migration history (Northcote et al 1992).…”

Interdecadal variation in seawater d13C and d18O recorded in fish otoliths

“…Similarly, atmospheric and oceanic d 18 O reservoirs appear to be coupled (Jouzel et al 2002), and carbonates precipitated in equilibrium with these reservoirs are affected by ambient concentrations as well as physicochemical conditions (Kim and O'Neil 1997;Thorrold et al 1997 Thorrold et al 1997;Elsdon and Gillanders 2002), and can lead to variability of otolith isotope signatures within and across years. Although otolith composition is also regulated by metabolic and physiological processes (Radtke et al 1987;Kalish 1991), these properties still yield consistent isotope signatures in otolith cores over annual time periods, justifying their use as natural tracers for specific water masses (Kerr et al 2007;Rooker et al 2008). Given the potential usefulness of otolith d 13 C and d 18 O for historical reconstructions (i.e., climate, physicochemical) and as natural tracers, evaluating the temporal variability of these signatures over decadal periods is critically needed.…”

“…Temperature, salinity, and ambient ocean isotope concentration have all been linked to changes in otolith d 13 C and d 18 O (Kalish 1991;Thorrold et al 1997;Elsdon and Gillanders 2002), and can lead to variability of otolith isotope signatures within and across years. Although otolith composition is also regulated by metabolic and physiological processes (Radtke et al 1987;Kalish 1991), these properties still yield consistent isotope signatures in otolith cores over annual time periods, justifying their use as natural tracers for specific water masses (Kerr et al 2007;Rooker et al 2008).…”