Photosynthetic performance, cell wall composition, and contaminant dynamics in intertidal Fucus vesiculosusBiology & Ecophysiology

Carme Pacín¹, Rubén Retuerto¹, Antonio Martínez-Cortizas¹, Irea Ferreiro¹, Teresa Boquete¹, Ángel Fernández¹, Antón Vázquez-Arias¹, Jesús R. Aboal¹

¹Universidade de Santiago de Compostela, Spain - ²Universidad Autónoma de Madrid, Spain

Intertidal seaweeds, such as Fucus vesiculosus, inhabit harsh environments characterized by fluctuating temperatures, variable levels of insolation, and periods of emersion. These stressors can impact their photosynthetic efficiency, biochemical composition, and interactions with other stressors, such as contaminants. Here, we investigated the physiological and biochemical responses of F. vesiculosus to emersion stress, focusing on the relationship between chlorophyll fluorescence, cell wall composition, and contaminant concentrations across thalli sections of different ages. The study specifically considered algae sampled along a grid spanning different distances from the shoreline, aiming to assess how desiccation stress varies with tidal exposure. Preliminary findings reveal significant effects of exposure time and dichotomy on photochemical efficiency, with younger tissues exhibiting enhanced fluorescence compared to older sections, especially in algae located farther from the shoreline. Furthermore, we hypothesize that younger tissues (apical most dichotomies), with higher regeneration capacity, exhibit lower contaminant levels and distinct alginate composition, again, showing a pronounced difference in individuals growing farther from the shoreline. This study provides insights into the interplay between tissue characteristics, pollutant dynamics and photosynthetic performance under dessication, contributing to our understanding of seaweed resilience in intertidal habitats.