Ecologies

Climate change poses serious challenges to Mediterranean crops such as the olive tree (Olea europaea L. subsp. europaea), underscoring the need for cultivars with improved drought tolerance and disease resistance. This study investigates variability in leaf and wood traits among Moroccan and introduced olive cultivars and their crossbreed genotypes grown under similar conditions. Specifically, we assessed (1) variation in key functional traits, (2) the effects of crossbreeding combinations, and (3) trait syndromes shaped by selection. Results showed substantial intraspecific variation in leaf traits, including specific leaf area (SLA), specific leaf water content (SLWC), stomatal size (SS), and density (SD), indicating diverse strategies for resource use and plasticity. Crossbreed genotypes generally displayed higher SLWC and lower SLA, reflecting adaptation to water stress. Wood traits, particularly vessel size (SVS) and number (NVS), also varied, revealing trade-offs between hydraulic efficiency and safety. Notably, an increase in vessel size and hydraulic conductivity was correlated with oil content (OC%), while OC% increased with higher vessel and stomatal densities. Larger stomata increased conductance and fruit growth, while lower SLA was linked to higher yield. Multivariate analysis distinguished two genotype groups, consistent with parental combinations. Overall, crossbreeding generated novel functional diversity that may enhance adaptive potential. These findings highlight the value of integrating functional and anatomical traits into olive breeding programs to improve resilience and productivity under climate change.

Extracellular polymeric substances (EPS) are secreted by microalgae and contribute to protecting cells from damage induced by cadmium (Cd) exposure. However, the response mechanism of Chlorella sp. to Cd(II) stress as well as associated changes in the chemical properties (including functional groups and composition) of soluble EPS (SL-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB- EPS) in this microalga, remain unclear. This study aimed to investigate the role of EPS in enabling Chlorella sp. to resist Cd(II) stress. The results demonstrated that Cd(II) stress resulted in a significant inhibition of algal, chlorophyll a (Chl a) contents, and maximum photochemical quantum yield (Fv/Fm) of Chlorella sp., with 7 d EC₃₀ of 6 mg/L. Nevertheless, Cd(II) exposure significantly increased both superoxide dismutase (SOD) activity and EPS content. Fourier transform infrared (FTIR) spectroscopic analysis revealed that differences existed in the functional groups involved in Cd(II) binding across algal cell density, SL-EPS, LB-EPS, and TB-EPS. The carboxyl group was identified as the most prominent functional group and were found to play a crucial role in the adsorption of Cd(II). Additionally, Tryptophan-like protein substance in EPS may be the main component binding with Cd(II) in Chlorella sp. This study indicated that Chlorella sp. resisted Cd(II) stress by increasing SOD activity and EPS content, with protein-like substance containing tryptophan proteins in EPS which could also contribute to protection against Cd stress.

Microplastic (MP) pollution is an emerging environmental concern, yet its occurrence in remote high-mountain ecosystems remains poorly understood. This study investigated MP contamination in fish from Nero Lake, an alpine lake in northwestern Italy. Between 2023 and 2024, a total of 33 specimens of Salmo trutta, Phoxinus lumaireul, and Salvelinus fontinalis were analyzed. MPs were detected in 84% of specimens in 2023 and in 93% in 2024. Filaments were the predominant particle type, while polyethylene, polypropylene, and polyethylene terephthalate were the most common polymers. In 2024, polyamide was also detected and showed the highest Polymer Hazard Index (PHI = 12.22), indicating a high hazard risk (Grade III) and elevated toxicological potential. Contamination Factor values exceeded 10 in S. trutta, and Pollution Load Index values frequently surpassed 1, both suggesting established contamination. However, the limited number of specimens, particularly for P. lumaireul and S. fontinalis, reduces statistical power and increases the risk of Type II errors. Although no significant interspecific differences in MP counts were observed, results should be interpreted with caution. Larger sample sizes are recommended but remain difficult to obtain in alpine environments. These findings highlight the vulnerability of remote lakes to both local and long-range MP pollution sources.