Species-specific variation in cuttlebone δ[sup.13]C and δ[sup.18]O for three species of Mediterranean cuttlefish

Stable carbon (δ[sup.13]C) and oxygen (δ[sup.18]O) isotopes in cuttlebones of three species of Mediterranean cuttlefish (Sepia elegans, S. officinalis, and S. orbignyana) with different life histories were contrasted. Cuttlebone δ[sup.13]C and δ[sup.18]O were quantified at both the core and edge (representing early life and recent deposition, respectively) for all three species sampled from the southern Adriatic Sea in 2010 (n = 28). For S. officinalis, cuttlebone δ[sup.13]C and δ[sup.18]O values were both lower relative to S. elegans and S. orbignyana at the core by approximately 1.0-2.0 and 3.0 %e, respectively. Differences between core and edge in cuttlebone δ[sup.13]C and δ[sup.18]O were also observed for S. officinalis with observed values at the cuttlebone edge (recent) exceeding core (early life) values by 2.5 %o for δ[sup.13]C and 1.4 %o for δ[sup.18]O. Differences in isotopic composition across S. officinalis cuttlebones are possibly reflective of ontogenetic migrations from nearshore nurseries (lower seawater δ[sup.13]C and δ[sup.18]O values) to offshore overwintering habitats (higher seawater δ[sup.13]C and δ[sup.18]O values). Overall, results from this study suggest that cuttlebone δ[sup.13]C and δ[sup.18]O hold promise as natural tags for determining the degree of spatial connectivity between nearshore and offshore environments used by cuttlefish.
Introduction Marine organisms often utilize both nearshore and offshore environments to complete their life cycle (Gillanders et al. 2003), and determining the degree of spatial connectivity among life stages is [...]