During the first two years of the project, the MitoRescue project progressed in line with its core objectives, completing WP1 and WP2 and initiating WP3. WP1 examined bioenergetic capacity, osmoregulation, and redox homeostasis of native (European) and invasive (Australian) Carcinus maenas populations under different pollution and temperature regimes. Sampling was conducted across multiple pristine and polluted sites, integrating physiological, biochemical, histological, and genetic analyses. Results revealed higher respiration rates in cold-adapted crabs, but similar osmotic and redox profiles across native populations. Invasive Australian crabs exhibited lower metabolism yet elevated antioxidant defences, with principal component analysis showing distinct physiological profiles. Genetic analyses linked these differences to high genetic variability, providing a first mechanistic link between genetic diversity and redox adaptation in invasive populations.
WP2 assessed mitochondrial tolerance to cadmium and copper, both well-known mitotoxicants. Results showed that historically cadmium-exposed crabs displayed pro-adaptive mitochondrial traits (elevated OXPHOS, ETS capacity, complex II activity, antioxidant defences), whereas naïve crabs exhibited acute shifts in complex activity likely aimed at reducing the production of reactive oxygen species, deleterious for cellular components and responsible for the induction of oxidative stress. These findings suggest long-term metal exposure fosters mitochondrial adaptations enhancing invasion success in polluted environments.
Methodological innovations included developing a permeabilized gill tissue protocol for marine invertebrates, improving in vivo relevance of mitochondrial assays. The project integrated whole-animal, tissue, and molecular approaches, incorporating sex as a biological variable and revealing sex-specific biochemical responses. WP3 sample collection was completed ahead of schedule, with imaging and gene expression analyses underway. The work has generated multiple conference presentations, one peer-reviewed publication, and several manuscripts in preparation, advancing evolutionary toxicology by establishing mitochondrial plasticity as a key factor in invasive species resilience to pollution and climate stress.