Novel approaches to monitoring light and noise pollution in subtidal coastal habitatsNovel Approaches

Martina Mulas¹, Francesca Rossi², Lucia Pini¹, Francesco Caruso², Simone Bava², Elena Maggi¹

¹University of Pisa, Italy - ²Stazione Zoologica ‘Anton Dohrn’, Italy

Artificial light at night (ALAN) and anthropogenic noise are two of the most concerning sensory pollutants of the 21st century. Scientific interest regarding the effect of marine light and noise pollution (LNP) has increased in the last two decades, nonetheless their combined effect is still poorly understood. Novel multimodal approaches following standardized protocols are needed to provide comparable measurements for preventing and mitigating their negative impacts at a global scale. Within this framework, the Horizon EU AquaPLAN project aims at investigating the consequences of these combined effects on different aquatic habitats, from freshwater to marine systems. The first step involves the implementation of a long-term monitoring program to characterize crossed LNP conditions: Low ALAN/High Noise, Low ALAN/Low Noise, High ALAN/High Noise, and High ALAN/Low Noise.
The joined team of Pisa University and the Zoological Station ‘Anton Dohrn’ focuses its research on two Mediterranean shallow subtidal habitats: Posidonia oceanica meadows and Cystoseira s.l. forests. These habitats are crucial in sustaining ecosystem functions and biodiversity, and their degradation could have broad implications for coastal resilience globally. P. oceanica meadows represent a biogenic habitat often exposed to human activity pressures, such as land illumination and vessel noise, with potential direct and indirect effects on both the plants and the epiphytic leaf assemblages they support. In summer 2024, we initiated the monitoring of seven P. oceanica meadows along the Tuscan and Ligurian coasts, from urbanized coastlines to MPAs, under different LNP conditions. Discrete ALAN measurements were collected during new-moon nights in the blue, green and red wavelengths with an underwater housed flatLAN, while soundscapes were recorded via passive acoustic monitoring throughout autonomous recorders. Seagrass samples coupled with in-situ measurements were collected to assess meadows health and identify the associated epiphytic communities. Epiphytes, known as stress sentinel, can serve to detect early responses to LNP stimuli. Here we present the first results of this novel monitoring approach with a special focus on the epiphyte community associated with P. oceanica leaf biogenic substrates.