Miriam Ferretti1, Elena Maggi1, Lisandro Benedetti Cecchi1, Francesca Rossi2
1Università di Pisa, Italy - 2Stazione Zoologica Anton Dohrn, Italy
Man-made structures are often equipped with Artificial Light At Night (ALAN). Yet, evidence of the ecological impact of ALAN within artificial substrates is limited. This study examines how ALAN affects the trophic ecology of the intertidal marble crab Pachygrapsus marmoratus inhabiting breakwaters. At two sites along the French Mediterranean coast, we selected dark and lit areas. Crab specimens and macroalgal samples were collected at each area and analysed for the stable isotopes of carbon (13C) and nitrogen (15N). Generalized Linear Mixed Models (GLMMs) and isotopic niche metrics using the R package SIBER were used to assess changes in diet, isotopic niche and trophic position of P. marmoratus according to the presence of light at night. The isotopic niches were narrower in lit than dark areas, although some variation occurred among sites. ALAN effects were mainly due to changes in the 13C range, indicating a restriction in diet items under lit conditions. Observed ALAN-induced diet changes could be due to a change in crab movement or to indirect effects on food sources. This is the first study to report changes in the isotopic composition of a secondary consumer under ALAN exposure, highlighting potential cascading impacts on food web structures in coastal ecosystems.
Biography
Ferretti graduated in Marine Biology at the University of Naples Federico II (2020). She is finishing a PhD in Marine Ecology at the University of Pisa focusing on benthic community responses to ALAN and urbanization via field experiments, isotope analysis, and ecoacoustics. She joined the AQUACOSM project (2019) on heatwave effects on pelagic communities in the Thau Lagoon (FR). She worked as a research fellow at Stazione Zoologica A. Dohrn as technical support for monitoring activities (2021)