Strategies of echinoderms in response to ocean acificacion: An "omics" approach from a natural laboratoryBiology & Ecophysiology

Vanessa Arranz¹, Robert Vilert-Fernandez¹, Marta Martin-Huete¹, Lea Schmütsch¹, Cinta Pegueroles², Rocio Pérez-Portela¹

¹ Universitat de Barcelona, Spain, ² Universitat Autonoma de Barcelona, Spain,

Ocean acidification (OA), driven by the rapid increase in atmospheric CO2 since the Industrial Revolution, presents a significant threat to marine biodiversity. By 2100, ocean acidity is predicted to rise by 100-150%, potentially disrupting half of marine species. The resilience, adaptability, and survival potential of marine organisms under OA conditions vary greatly across species, and the broader ecological consequences remain poorly understood. Marine CO2 vents, which create natural pH gradients over short geographical distances, serve as a proxy to study long-term OA effects and provide a glimpse into future ocean scenarios. In this study, we focus on Arbacia lixula, an important echinoderm species, collected from both ambient (pH 8.1) and CO2 vent sites (pH 7.4) along a natural pH gradient in La Palma, Canary Islands. We employed a multidisciplinary approach that integrates transcriptomics, microbiome profiling, and metabolic analysis to uncover the biological mechanisms underpinning adaptation and plasticity to OA. By examining intra- and inter-specific processes, we highlight the complex biological characteristics that determine the species’ capacity to survive in rapidly changing environments. This includes exploring adaptive evolution versus phenotypic plasticity, and the role of the holobiont—the host and its associated microbiota—in influencing these responses. We present data on genomic variation, gene expression changes, metabolic rates, and shifts in microbiota composition under natural and experimental conditions. Our findings provide insight into the buffering systems and adaptive strategies used by A. lixula to cope with OA, contributing to our understanding of the resilience potential of marine organisms. This research fills critical gaps in ecological genomics and offers predictions about the capacity of marine species to withstand future OA scenarios, with important implications for biodiversity conservation.