Using segmental isotope analysis of teleost fish vertebrae to estimate trophic discrimination factors of bone collagen

Abstract

We conducted feeding experiments with sardine (Sardinops melanostictus) and Japanese flounder (Paralichthys olivaceus) to investigate trophic discrimination factors (TDFs) in bone collagen using retrospective isotope analysis. Sardines and Japanese flounder were fed a single diet for 9 months and 4 months, respectively. At the end of the experiments, we extracted vertebral centra from six sardines and seven Japanese flounder and subdivided them into multiple sections. We extracted bone collagen from each section, and measured the δ13C and δ15N of each vertebral section and food source. In all fish samples, the δ13C and δ15N values of bone collagen increased from the centers of vertebrae to the marginal sections. This trend was consistent with the predicted isotopic shift in the diets of these fishes. The TDFs for sardines were estimated at 5.58 ± 0.25‰ (mean ± SD) for δ13C and −0.70 ± 0.25‰ for δ15N; those for Japanese flounder were 3.89 ± 0.14‰ for δ13C and 1.18 ± 0.35‰ for δ15N. Our results show that segmental analysis of vertebrae can reconstruct δ13C and δ15N values for multiple life‐stages of both fish species and is useful for estimating TDFs and turnover times of fish bone collagen.

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

“…Second, isotope values in each vertebral section are unchanged from the values at the time when each section was created. Matsubayashi et al (2017, 2019) provided evidence of a minimal effect from replacement‐based turnover in collagen from vertebral bone in fishes. Third, the natal river of individual salmon is the same as the sampled river.…”

“…Recent studies have developed a method to perform retrospective δ 15 N analysis in teleost fishes using their vertebrae (Matsubayashi et al 2017, 2019). Fish vertebrae exhibit incremental growth, and isotopes incorporated into the bone collagen of each vertebral section remain in place for a long time in the absence of active metabolic tissue replacement.…”

“…We constructed an isoscape of δ 15 N Base in the North Pacific using the δ 15 N Bulk and δ 15 N AAs of copepods collected from the migration area of chum salmon. Then, we performed retrospective δ 15 N AAs analysis of vertebral sections extracted from bodies of spawning salmon, and measured δ 15 N Base for successive growth stages of each fish (Matsubayashi et al 2017, 2019). Finally, we developed a state‐space model to estimate migration routes of individual salmon by using δ 15 N Base isoscapes in the North Pacific and δ 15 N Base time‐series in salmon, and compared the results with a known migration route of chum salmon from Japan to the Bering Sea.…”

Effects of formalin preservation on carbon and nitrogen stable isotopes of seaweeds: A foundation for looking back in time

“…The use of preserved seaweeds to study nutrient loading and energy flow in marine food webs is an underutilized tool that would complement an already rich assemblage of studies of historical trophic structure. In lieu of using seaweeds as a nutrient baseline, some recent studies of marine systems have applied compound‐specific stable isotope analysis of amino acids (CSIA), which eliminates the need for nutrient baselines from nitrogen isotopes (Chikaraishi et al 2014; Ruiz‐Cooley et al 2014; Matsubayashi et al 2018; Wu, et al 2018; Phillips et al 2020; Quillfeldt and Masello 2020); however, this method is considerably more expensive than bulk tissue isotope analysis. The less expensive option of using preserved macroalgae and cyanobacteria as a nutrient baseline, where applicable, would allow studies of historical marine trophic structure to be more widespread and accessible.…”

Using geostatistical analysis for simultaneous estimation of isoscapes and ontogenetic shifts in isotope ratios of highly migratory marine fish

“…Understanding isotopic offsets between isoscape and target animal requires feeding experiments over several months (e.g. Matsubayashi et al, 2019;Canseco et al, 2021). Furthermore, in the case of highly migratory piscivorous species, understanding the ontogenetic shifts of d 13 C and d 15 N is particularly difficult because isoscapes and ontogenetic dietary shifts have mutual interactions.…”