Spatial models cannot compensate for sampling designs unstructured relative to isotopic variation: implications for baseline isoscape development in the Mediterranean Sea
Özet
Isoscapes – spatial models of stable isotope ratios – are powerful tools for understanding biogeochemical cycles, food web structure, and ecological connectivity. In marine systems, however, broad-scale isoscapes are difficult to constrain because reference datasets are typically heterogeneous and opportunistic. Bayesian hierarchical models implemented through Integrated Nested Laplace Approximation (INLA) provide an efficient framework for modeling spatial patterns while accounting for non-spatial variance. We tested whether broad-scale geographic baseline isoscapes could be constrained for the Mediterranean Sea using INLA models applied to an opportunistically compiled dataset from this semi-enclosed basin, where strong environmental gradients are expected but spatially explicit baselines remain lacking. We assembled the most comprehensive dataset of δ13C and δ15N values to date for low-trophic-level, primarily epipelagic food web compartments (> 6,000 samples from > 600 sites). Although discrete regions of relatively high and low δ values were identified, particularly for δ15N, semivariograms and model outputs indicated only short-range spatial autocorrelation (ca. 40 km for δ13C; 65 km for δ15N) within this large dataset. Environmental covariates improved model fit for δ15N values but did not enhance predictive performance or alter spatial predictions. Our results demonstrate that even advanced spatial models may not compensate where sampling design is structurally mismatched relative to unknown but structured spatial and non-spatial sources of isotopic variation. Coordinated sampling designed to capture spatial variability while accounting for major sources of non-spatial variance is required to develop robust marine isoscapes supporting ecological and management applications in the Mediterranean Sea and similar regions.
Anahtar kelimeler
Atıf için künye
Magozzi, S., Trueman, C. N., Cobain, M. R., MacKenzie, K. M., John Glew, K. S., Canseco, J. A., Díaz-Delgado, E., Fanelli, E., Rumolo, P., Cartes, J. E., Espinasse, B., Agnetta, D., Albo-Puigserver, M., Alomar, C., Alvisi, F., Badalamenti, F., Bănaru, D., Berto, D., Bonanno, A., … Willis, T. J. (2026). Spatial models cannot compensate for sampling designs unstructured relative to isotopic variation: implications for baseline isoscape development in the Mediterranean Sea. Progress in Oceanography, 248. https://doi.org/10.1016/j.pocean.2026.103794
BibTeX
@article{magozzi2026-293998,
author = {Magozzi, Sarah and Trueman, Clive N. and Cobain, Matthew R.D. and MacKenzie, Kirsteen M. and John Glew, Katie St. and Canseco, José A. and Díaz-Delgado, Eric and Fanelli, Emanuela and Rumolo, Paola and Cartes, Joan E. and Espinasse, Boris and Agnetta, Davide and Albo-Puigserver, Marta and Alomar, Carme and Alvisi, Francesca and Badalamenti, Fabio and Bănaru, Daniela and Berto, Daniela and Bonanno, Angelo and Bonaviri, Chiara and Bongiorni, Lucia and BÜYÜKATEŞ, YEŞİM and Calafat Frau, Antonio M. and Camatti, Elisa and Cantoni, Carolina and Cardona, Luis and Carlier, Antoine and Castellano, Michela and Chaikalis, Spyros and Chiggiato, Jacopo and Cibic, Tamara and Conan, Pascal and Conese, Ilaria and Coppari, Martina and Costalago, David and Cresson, Pierre and D'Ambra, Isabella and Dähnke, Kirstin and Darnaude, Audrey M. and Deudero, Salud and Ezgeta-Balić, Daria and Giani, Michele and Gogou, Alexandra and Grégori, Gérald and Guy-Haim, Tamar and Harmelin-Vivien, Mireille L. and Jennings, Simon and Karageorgis, Aristomenis P. and Koppelmann, Rolf and Lampadariou, Nikolaos and Langone, Leonardo and Liénart, Camilla and Mazzocchi, Maria Grazia and Mazzola, Antonio and Meador, Travis B. and Merquiol, Louise and Metzke, Marc and Miserocchi, Stefano and Möbius, Jürgen and Mostajir, Behzad and Mousseau, Laure and Navarro, Joan and Ogrinc, Nives and Pansera, Marco and Pantoja-Gutiérrez, Silvio and Papiol, Vanesa and Parinos, Constantine and Pasqual, Catalina and Pavlidou, Alexandra and Pedrosa-Pàmies, Rut and Pinnegar, John and Polunin, Nicholas V.C. and Protopapa, Maria and Repeta, Daniel J. and Sabatino, Nadia and Sachs, Julian P. and Sanchez-Vidal, Anna and Sarà, Gianluca and Savoye, Nicolas and Schroeder, Anna and Skylaki, Ester and Sigman, Daniel M. and Signa, Geraldina and Sisma-Ventura, Guy and Stavrakaki, Ioanna and Struck, Ulrich and Tesán-Onrubia, Javier A. and Tesi, Tommaso and Uzundumlu, Sinan and Valls, Maria and Vizzini, Salvatrice and Zervoudaki, Soultana and Zgozi, Salem W. and Zoppini, Annamaria and Zorica, Barbara and Willis, Trevor J.},
title = {Spatial models cannot compensate for sampling designs unstructured relative to isotopic variation: implications for baseline isoscape development in the Mediterranean Sea},
journal = {Progress in Oceanography},
year = {2026},
volume = {248},
issn = {0079-6611},
doi = {10.1016/j.pocean.2026.103794},
url = {https://akademik.atauni.edu.tr/yayinlar/293998-spatial-models-cannot-compensate-for-sampling-designs-unstructured-relative-to}
}