Heatwave Responses in Native and Allochthonous Sporobolus: A Multi-Disciplinary Perspective

Submission 40

Oral-02

Presented by: Filippo Drigo

Filippo Drigo ^{1, 2}, Pietro Antolini ¹, Isabella Moro ^{1, 2, 5}, Cristiano De Pittà ^{1, 2}

¹ Department of Biology, University of Padova

² National Biodiversity Future Centre (NBFC)

³ Centro de Ciências do Mar do Algarve, Universidade do Algarve

⁴ Pediatric Research Institute “Città della Speranza”

⁵ Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn

The Venice Lagoon is a transitional environment, highly impacted by anthropogenic activities and global climate change. It is also considered a hot spot for biodiversity and biological invasion. Here, Sporobolus maritimus is a native halophyte, currently threatened by the spreading of the non-indigenous species S. anglicus and extreme climatic events, like heatwaves, which are reported with increasing frequency in the Venice Lagoon.

We exposed S. maritimus and S. anglicus organisms to a simulated five-day heatwave and assessed the morphological, physiological and biochemical responses. These data were integrated with gene expression and metabolite profiling. To identify differentially expressed genes, we also generated and annotated a de novo transcriptome for Sporobolus species.

We observed a decline in the survival rate of S. maritimus, whereas S. anglicus showed no increase in mortality. Consistent with this pattern, morphological (structure of the photosynthetic apparatus), physiological (photosynthetic efficiency and pigment content) and biochemical assays (antioxidant enzyme activity) indicated that the native species is more susceptible to heatwave stress and exhibits limited recovery. In contrast, S. anglicus demonstrated greater tolerance and a clear capacity to recover for all analysed parameters. Gene expression analyses further suggest that the response of S. maritimus is slower and more severely impacted, whereas S. anglicus shows a faster and more effective response, highlighting the greater resilience of the non-indigenous species.

Overall, our results indicate that the non-indigenous species S. anglicus responds more rapidly to heat stress, limiting damage to the photosynthetic apparatus and coping more effectively with prolonged stress, compared to the native species S. maritimus. Taken together, these findings indicate that S. anglicus is more resilient to heat stress than S. maritimus, raising serious concerns about its persistence in the Venice Lagoon under future climate scenarios and related ecological impacts.

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