Biodiversity and Environmental Stressors: Some applications to mud volcanoes

Halophytic species thriving in these environments display remarkable phytochemical resilience through specialized metabolite production. In Atriplex sagittata Borkh. (Nirano), 64 compounds, including flavonoids and phenylethylamine alkaloids, were identified. Sulfated flavonoids and alkaloids were enriched in populations exposed to higher salt inputs (Na⁺, Cl⁻, Br⁻). Similarly, Puccinellia fasciculata (Torr.) E.P.Bicknell exhibited enhanced production of sulfated flavonoids and alkaloids in the more saline soil of Ferdinando cone, and its polar extract inducing up to 85.3% mortality in Drosophila melanogaster, indicating environmentally triggered bioactive defenses. We studied the metabolome of Lavatera agrigentina Tineo and Suaeda vera Forssk. ex J.F.Gmel collected in Maccalube Nature Reserve and in a nearby stress-free environment. Analysis of the hydroalcoholic extract of S. vera using by LC-MS revealed a rich phytochemical profile, including flavonoids and sulphated flavonoids, phenylethylamine alkaloids and phenolic compounds. Similarly, HR-ESI-MS analysis of L. agrigentina identified metabolites such as flavonoids, coumarins, and terpenes. Comparative analysis showed that plants from the stress-free environment  produced lower levels of abscisic acid, glycosylated, and sulphated derivatives.

Radionuclide measurements in soils, mud and water pools complemented the botanical observations, revealing significant site-specific behavior. High concentrations of radon (²²²Rn) were detected exclusively at active mud emission centers, correlating with gas bubbling flows. Gamma spectrometry of mud, soil, and plant tissues (²²⁶Ra, ²³²Th, ⁴⁰K, ¹³⁷Cs) indicated generally homogeneous distributions; however, ⁴⁰K levels in dried plants were linked to biological activity, suggesting an interplay between vegetation and the radioactive properties of volcanic substrates.

This study, conducted on both Nirano and Maccalube Nature Reserves, was supported by the PROMUD (PROtocol for MUD volcanoes) project, funded by the Italian Ministry of University and Research INGV Pianeta Dinamico Project. The results show how the  plant species, particularly halophytes, can modulate their specialized metabolite pathways in response to environmental stressors in sedimentary volcanic settings. These findings underscore the value of sedimentary mud volcanoes as natural laboratories for studying environmental stress adaptation and biogeochemical interactions.