Otolith δ18O of Pacific bluefin tuna Thunnus orientalis as an indicator of ambient water temperature

Marine Ecology Progress Series

Akira Shinoda¹  Takashi Kitagawa¹  Kotaro Shirai¹  Tsuguo Otake¹  Shingo Kimura¹  Rena Uozato¹  Toyoho Ishimura¹  Urumu Tsunogai¹  Yosuke Amano¹ 

关键词: Pacific bluefin tuna;    Thunnus orientalis;    Otolith;    δ18O;    Temperature indicator;   

DOI  :  10.3354/meps10202

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: To detect the relationship between ambient temperature and otolith stable oxygen isotope (δ¹⁸O), Pacific bluefin tuna Thunnus orientalis larvae were reared at 6 different temperatures (between 23 and 28°C at 35 psu; mean δ¹⁸O value, +0.31‰) for 2 to 8 d after hatching. For the first time, otolith δ¹⁸O was measured using a continuous-flow isotope ratio mass spectrometry system. The linear relationship between otolith δ¹⁸O and temperature was determined as follows: δ_otolith – δ_water = –2.70 (T°C) + 5.193 (r² = 0.806, p < 0.01). The temperature-dependent fractionation of otolith δ¹⁸O was close to that reported for inorganic aragonite, indicating that the vital effects of isotopes are small. The otolith δ¹⁸O values of juveniles reared at a mean of 26.5°C were not significantly different from those of larvae reared at 26°C. With regard to the 2 pairs of otoliths within an individual fish, the differences in δ¹⁸O values between the left and right otoliths were subtle. The otolith δ¹⁸O values of larvae reared in δ¹⁸O-depleted seawater (24 to 26°C at 32 psu; δ¹⁸O, –0.17‰) were lower, but were not significantly different from those of larvae reared in +0.31‰ water, which is the δ¹⁸O value of the water in which the spawners were raised. These results suggest that the sample size for the 32 psu experiment was too small and that the rearing durations were too short to affect the otoliths completely. Our results demonstrate that otolith δ¹⁸O values of Pacific bluefin tuna larvae can provide precise and accurate estimates of their ambient temperature experience.

【 授权许可】

Unknown