[eng] Human activities have significantly impacted Earth's ecosystems, leading to habitat changes
and species extinctions. Human civilization has historical and evolutionary links to the ocean
which has served as a vital source of essential biomolecules, sustenance and a key space for
transport and commerce. However, overfishing, pollution, and other stressors have dramatically
altered marine ecosystems globally. The Mediterranean is home to over 7% of global marine
biodiversity and has been overexploited for over 2000 years and, therefore, it is facing severe
degradation aggravated due to its semi-enclosed nature and high population density. Stable
isotopes provide crucial insights into trophic pathways and feeding interactions in aquatic
ecosystems. Analysing carbon (δ13C) and nitrogen (δ15N) isotopic signatures in tissues helps to
determine the organisms' position in the food web. This study aims to assess the impact of
human settlements over time on marine environments through stable isotope analyses on
archaeological and modern fishbones. Mandibular and premaxillary bones from Sparus aurata,
Pagrus pagrus, Pagellus erythrinus, Pagellus genus, Labrus genus and Diplodus genus were
collected. Archaeological bones were obtained from the Roman port city of Pollentia, while
modern samples were fished at the Bays of Palma and Alcúdia. All bones went through a
collagen extraction protocol for the subsequent δ13C and δ15N stable isotope analysis.
Additionally, regression models were employed to estimate the Standard Length (SL) of
archaeological specimens. Statistical analysis, performed using R, aimed to uncover isotopic
variations across species and time periods showed that, despite the C:N ratio suggesting that the
collagen quality of the samples does not meet standard thresholds, our results show a clear trend,
as all archaeological samples showed enriched δ13C and δ15N mean values compared to modern
samples. Moreover, archaeological samples exhibit a notable dispersion with very distinct
isotopic outcomes when compared to modern ones. In addition, archaeological species are
considerably larger than modern ones.