Journal Article

Interdecadal Variation in Seawater δ¹³C and δ¹ɸO Recorded in Fish Otoliths

Neilson, John D., Louchuoarn, Patrick, Secor, David H., Schloesser, Rayan W., Rooker, Jay R.

2009

Overview

Stable carbon (δ¹³C) and oxygen (δ¹ɸO) in the otolith cores of Atlantic bluefin tuna (Thunnus thynnus) vary temporally, with changes that quantitatively follow interdecadal variation in atmospheric and oceanic reservoirs. Both carbon and oxygen isotopic signatures vary significantly by year of birth over the range investigated (1947–2006), with δ¹³C decreasing and δ¹ɸO increasing (- 2.56 × 10 ¯ 2 ‰ and 4.3 × 10⁻³% o yr⁻¹, respectively). The rate of change in otolith δ¹³C was similar to reported rates of atmospheric δ¹³C depletion, attributed to deforestation and the burning of fossil fuels (referred to as the Suess effect), suggesting a close link between atmospheric and oceanic carbon pools. Increases in otolith δ¹ɸO were evident but less pronounced, with observed variation possibly attributable to changing salinity in the Atlantic Ocean. Otolith cores of bluefin tuna effectively track interdecadal trends and record past seawater δ¹³C and δ¹ɸO.

• Publisher: American Society of Limnology and Oceanography