Laser ablation–accelerator mass spectrometry reveals complete bomb 14C signal in an otolith with confirmation of 60-year longevity for red snapper (Lutjanus campechanus)

Abstract

Bomb-produced 14C has been used to make valid estimates of age for various marine organisms for 25 years, but fish ages that lead to birth years earlier than the period of increase in 14C lose their time specificity. As a result, bomb 14C dating is limited to a minimum age from the last year of prebomb levels because the temporal variation in 14C in the marine surface layer is negligible for decades before c. 1958. The longevity of red snapper (Lutjanus campechanus) in the Gulf of Mexico remains unresolved despite various forms of support for ages near 50–60 years. Although the age and growth of red snapper have been verified or validated to a limited extent, some scepticism remains about longevity estimates that exceed 30 years. In this study, red snapper otoliths were analysed for 14C using a novel laser ablation–accelerator mass spectrometry technique to provide a continuous record of 14C uptake. This approach provided a basis for age validation that extends beyond the normal limits of bomb 14C dating with confirmation of a 60-year longevity for red snapper in the Gulf of Mexico.

Bomb-Produced Radiocarbon Across the South Pacific Gyre—a New Record From American Samoa With Utility for Fisheries Science

“…Alternatively, a full study can be facilitated with limited juvenile collections or otolith edge material of young fish that cover a portion of the decline period, with the assumption that the trend of otolith 14 C alignment continues in unison with the coral 14 C reference (i.e., Andrews 2020; Barnett et al 2018;Andrews et al 2020b, Andrews andScofield 2021). Use of the post-peak bomb 14 C decline has also evolved with a novel line of research that uses core material of fish eye lenses to validate age (Patterson et al 2020) and in the use of new technology (laser ablation accelerator mass spectrometry) to trace continuous bomb 14 C signals within an otolith (Andrews et al 2019b).…”

Eye lens Δ14C validates otolith-derived age estimates of Gulf of Mexico reef fishes

“…Typically, 100 g of C is required for robust analysis of  14 C with accelerator mass spectrometry (AMS), which translates to 1 mg of otolith material given otoliths are approximately 12% C by mass. Low-mass analysis is possible (to approximately 10 g), and recent advances in laser ablation-AMS provide a means to microsample ultra-low C masses from otolith sections (Andrews et al 2019). However, progressively greater measurement error typically occurs with decreasing sample mass.…”

Early overcounting in otoliths: a case study of age and growth for gindai (Pristipomoides zonatus) using bomb 14C dating

“…A method called bomb radiocarbon ( 14 C) dating can directly assess the accuracy of fish age estimates from otoliths and has evolved considerably over the last 28 years (Andrews et al, 2019b;Kalish, 1993). There is a long history of success with this approach where it has been used to validate or invalidate purported annual growth zones (Andrews et al, 2013;Campana, 1999;Kalish, 1995).…”