Morphological and physiological effects of lead exposure on thalli of Iridaea cordata (Turner) Bory collected in Antarctica

Antarctica, even if it’s considered as the last pristine continent on Earth, is contaminated by different environmental pollutants, among which heavy metals released by human activity, cause serious changes in the aquatic environments. The concern by lead pollution is increasing due to its high toxicity even at low concentrations. Lead (Pb) is one of the major contaminants arising from human activities in Antarctica and it is not an essential element for photosynthesis, but it can be easily absorbed and accumulated by photosynthetic organisms. This work is aimed to evaluate the morphological and physiological effects of lead in the Antarctic rhodophycean species: Iridaea cordata (Turner) Bory. To evaluate the toxicity of this pollutant, different analyses have been carried out, such as the evaluation of photosynthetic pigments, the determination of enzymes antioxidants (as catalase, superoxide dismutase, glutathione-S-transferase and ascorbate peroxidase), the untarged metabolomics and the analysis of morphology and ultrastructure through the use of the transmission electron microscope (TEM). The statistical method used is the one-way ANOVA test. Iridaea cordata thalli exposed in Antarctica to two different concentrations of lead showed discolouration of thallus pigmentation, decrease in photosynthetic pigments and increase in antioxidant enzymes.