Fig. 3
From: Insights on long-term ecosystem changes from stable isotopes in historical squid beaks
Differences in δ13C values (a–d), estimated trophic position (e–h) and specialization index of δ13C (i, k) and trophic position (j, l) among different time series of Gonatus fabricii and Todarodes sagittatus between 1844 and 2023. a, e. Gonatus fabricii with mantle length (ML) 6.6–7.5 mm (= beak subsection 1). b, f. Gonatus fabricii ML 54.9–64.5 mm (= beak subsection 8). c, g. Todarodes sagittatus ML 9.1–10.0 mm (= beak subsection 1). d, h. Todarodes sagittatus ML 72.7–80.4 mm (= beak subsection 8). i. Specialization index of δ13C, entire beaks of G. fabricii. j. Specialization index of trophic position, entire beaks of G. fabricii. k. Specialization index of δ13C, entire beaks of T. sagittatus. l. Specialization index of trophic position, entire beaks of T. sagittatus. Boxplots indicate mean values (midlines), upper and lower quartiles (box limits) and standard errors (whiskers). All individual data points are shown. Figures from subsection 1 are labelled as small squid, and figures from subsection 8 are labelled as large squid