巴勒莫大学

Rare earth elements (REEs) are increasingly recognised as emerging contaminants, yet their transfer from sediment and water to biota remains poorly understood in coastal marine systems characterised by shallow-water hydrothermal vents. These vents release REEs at concentrations approaching those of anthropogenically impacted sites, providing a natural laboratory to investigate their transfer to marine biota. REE distribution and sediment-to-biota transfer were characterised along the pH gradient of the shallow CO2-vent system of Levante Bay (Vulcano Island, southern Tyrrhenian, Italy), combining sediment analyses with those of three co-occurring, functionally distinct organisms representing complementary exposure pathways: the seagrass Cymodocea nodosa, the sea anemone Anemonia viridis, and the benthic goby Gobius incognitus. REE concentrations decreased overall along the sequence: sediment > C. nodosa > G. incognitus > A. viridis. Biota-Sediment Accumulation Factor (BSAF) values were below unity in all matrices at both areas, indicating limited transfer despite hydrothermal enrichment. Post-Archean Australian Shale (PAAS) normalised REE patterns, diagnostic anomalies and multivariate ordination revealed three distinct biotic signatures in species sharing the same hydrothermally enriched environment: a sediment-like, light REE-enriched profile in A. viridis; a relatively heavy REE-enriched, biologically fractionated profile in C. nodosa; and a low, dispersive profile in G. incognitus. The latter was the only matrix showing higher BSAF at both low-pH sites, possibly reflecting the dietary pathway. Differences in REE accumulation among matrices exceeded those between the two pH conditions. These results indicate that co-occurring species exhibit distinct REE signatures and that the choice of bioindicator embeds a specific exposure pathway.

Studying erosion and sedimentation at different spatial scales, the concept of connectivity represents the physical linkage among different structural elements within a basin regarding flows and associated sediments. Sediment delivery ratio is considered a measure of sediment connectivity, and it can be related to the basin structural connectivity (morphological unit and travel time) and the hydrological connectivity (rainfall-runoff processes). In this study, sediment connectivity was assessed by the SEdiment Delivery Distributed (SEDD) model and sediment yield data for 73 events at the SPA2 experimental basin (Sicily, Italy) in the period 2000–2022. For this basin, the coefficient βL of the structural component of the sediment delivery ratio, SDRi, of each morphological unit was estimated using the frequency distribution of the travel time for each morphological unit. Subsequently, using event sediment yield data, the coefficient βF of the functional component of SDRi was estimated by SEDD. This analysis showed that the functional connectivity depends on the erosion event magnitude, and for low events, the global sediment connectivity is controlled by its structural component. At the annual scale, SEDD was calibrated establishing a relationship between the annual coefficient βF,a of the functional component and the rainfall erosivity. Finally, an uncertainty analysis was developed by Monte Carlo simulations to establish the influence of knowledge uncertainty and the stochastic variability of the model parameters on calculated sediment yield.

Marine protected area (MPA) implementation can alter fishing access and generate opposition to conservation efforts. Yet, evidence on how MPAs are associated with changes in small-scale fishing operations remains limited. Surveys and participatory mapping exercises (n = 93) were carried out with small-scale fishers in four Mediterranean and one Black Sea MPA to examine reported behavioural responses and perceptions associated with MPA implementation. Across the four MPAs investigated with implemented fisheries restrictions (for the one in Black Sea no changes in restrictions were recorded), respondents reported a reallocation of fishing activity away from newly restricted areas and most often towards areas previously known to them. A pattern consistent with regulatory displacement, but also with site-fidelity and cost-minimising spatial behaviour. Multinomial logistic regression highlighted that the number of fishing gears used and perceived effects of the MPA on access to productive fishing grounds were significantly associated with reported reallocation strategies: fishers using more gears (i.e., more diverse fishery portfolio) were more likely to fully reallocate elsewhere, whereas fishers who perceived that the MPA improved access to productive grounds were less likely to report partial or total reallocation. MPA implementation was not associated with changes in the mean number of fishing gears used. Most fishers reported low perceived adaptation to the MPA, while higher involvement in decision-making was associated with higher perceived level of adaptation. Our study highlights multiple elements influencing how fishers adjust to protection and their perceived capacity to adapt to changing management regimes.

Microbial strains belonging to the Actinomycetota phylum are known as plant growth-promoting (PGP) bacteria and are considered promising candidates for the development of biofertilizers due to their metabolic ability to produce diverse bioactive compounds. In this work, the actinomycetotal strains Kocuria rhizophila PA220 and Streptomyces violaceoruber DSM40783 were investigated using a two-step experimental approach: the first step focused on seed germination and provided visual evidence of initial seedling surface attachment via scanning electron microscopy (SEM); the second assessed PGP-associated responses in oregano rooted cuttings and relative differences in metabolite profiles, characterized through gas chromatography-mass spectrometry analysis of flowers volatilome. Seeds and rooted cuttings were inoculated (by priming or direct application, respectively) with the two individual strains or their consortium, alongside a non-inoculated control. For comparison, a commercial biofertilizer was included in the field experiment. Morpho-physiological parameters, including plant elongation and chlorophyll content, were monitored throughout growth. Both strains adhered to seedling surfaces, and S. violaceoruber was associated with higher seed germination rates. Under field conditions, S. violaceoruber was associated with higher chlorophyll content, whereas K. rhizophila was associated with increased shoot elongation at blooming. Increased relative abundances of p-cymene and terpinolene, monoterpenes with relevant bioactive properties, occurred alongside the actinobacterial consortium. Overall, these findings indicate that the tested actinomycetotal strains improved specific plant traits under both controlled and open-field conditions, and moreover align with changes on metabolite profiles. These results support further investigation of Actinomycetota-based biofertilizers as tools for sustainable management of Mediterranean aromatic crops.

This work investigates how toxin-mediated interactions and directed movements shape the emergence of coherent structures in plant-herbivore systems. The analysis focuses on a two-compartment model enclosing a toxin-dependent functional response and a cross-diffusion term that represents ecologically plausible herbivores' movement towards, or away from, vegetation. Two distinct dynamical regimes arise depending on toxicity strength. Under weak toxicity, the system admits at most one biologically feasible coexistence equilibrium, which may lose stability through a Hopf bifurcation generating small-amplitude temporal oscillations. Under strong toxicity, the nonlinear functional response becomes non-monotonic, allowing for multiple coexistence equilibria and abrupt regime shifts. The influence of cross-diffusion on stability is also examined, identifying the conditions under which Turing instabilities and mixed spatiotemporal patterns occur. Near the corresponding bifurcation thresholds, Stuart-Landau amplitude equations are derived via weakly nonlinear analysis, providing a unified framework for the modulation of oscillatory, stationary, and combined Turing-Hopf modes. Numerical simulations corroborate the theoretical predictions, illustrating transitions from spatially uniform states to oscillations, spatial patterns, and mixed behavior. Overall, this manuscript highlights how chemical defences, nonlinear feedbacks, and movement strategies jointly determine the emergence, selection, and robustness of coherent structures in plant-herbivore systems.