043 | Hemocyte motility integrated into a multimarker ecophysiological approach for thermal stress assessment in native and invasive bivalve species

Gayatri Udayan, Claudio Calabrese¹, Daniele Arduini; Antonella Giacovelli¹, Maria Elena Giordano¹, Adriana Giangrande^1|2, Maria Giulia Lionetto^1|2 | ¹Dept Biological and Environmental Sciences and Technologies DiSTeBA, University of Salento; ²NBFC, National Biodiversity Future Center, Palermo, Italy.

Climate change is driving an increase in both the intensity and recurrence of marine heatwaves in the Mediterranean sea, representing a serious challenge for native benthic organisms while simultaneously promoting the spread of thermophilic non-indigenous species. In this context, the identification of responsive biomarkers of environmental stress is crucial for monitoring ecosystem health. Bivalve mollusks are widely recognized as reliable sentinels of environmental change due to their pronounced sensitivity to multiple stressors. Among their defense mechanisms, hemocytes play a pivotal role in immune responses, with controlled cell motility being essential for efficient migration and immune surveillance. This study examines the ecophysiological responses of two bivalve species, the native mussel Mytilus galloprovincialis and the invasive oyster Pinctada radiata, collected from the Mar Grande of Taranto during the summer season. In recent years, this coastal area has been characterized by anomalously elevated summer seawater temperatures, offering a natural experimental framework for evaluating organismal responses to realistic thermal stress conditions. Hemocyte motility was assessed by time-lapse microscopy as a functional biomarker of immune performance and sublethal stress. This cellular parameter was integrated by lysosomal membrane stability assessment and by a suite of biochemical biomarkers measured in the digestive gland, including the activity of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase and glutathione S-transferase) and total protein content Thermal stress induced species-specific alterations in hemocyte motility, with potential consequences for immune efficiency and overall resilience to environmental challenges in warming marine ecosystems. Consistently, differences between species were also observed in lysosomal membrane stability, antioxidant defense profiles and protein levels in digestive gland tissues. Overall, these results highlight hemocyte motility as a sensitive and informative biomarker that can be integrated into multimarker ecophysiological frameworks to evaluate organismal vulnerability and adaptive capacity under climate-related thermal stress.
This study was funded by NBFC (National Biodiversity Future Center) funded by European Union NextGenerationEU, PNRR, project n. CN00000033, CUP: F87G22000290001.