Abstract Cold waves restrict the distribution of mangroves. This study examined the contribution of PSII heterogeneity and stomatal functioning to sustaining photochemistry and photoprotection in mangroves during a cold wave. We exposed eight populations of Kandelia obovata (cold-tolerant) and, Bruguiera gymnorhiza (cold-susceptible) from different latitudes to 27/20°C (favorable) and 10/3°C (chilling; simulated cold wave) day and night temperatures. Multiple trait responses imply that cold waves affected K. obovata the least. Significant changes in chlorophyll fluorescence transients (photosystem II [PSII]) with a slight decrease in the redox status of P700 (photosystem I [PSI]) imply a greater impact of a cold wave on PSII. During the cold wave, photochemical efficiency of PSII, efficiency of the water-splitting complex, light absorptance, stomatal pore area, cyclic electron flow, nonphotochemical quenching, and number of active PSIIα and PSII QB reducing centers decreased, while light transmittance, night respiration, and inactive PSII QB nonreducing, PSIIβ, and γ centers increased in both species. The population of K. obovata from the coldest latitudinal site (Fujian, China) was least affected by cold wave due to local evolutionary adaptations. Modulation of PSII heterogeneity and stomatal functioning is important to sustaining photochemistry and photoprotection in mangroves to cope with cold waves. Highlights PSII heterogeneity and stomatal functioning support mangroves to cope with cold waves. Local evolutionary adaptations promote the cold tolerance of mangrove populations.
We evaluated a digital learning programme for non-specialists to develop knowledge-based competencies in a problem-solving intervention for adolescents to examine the overall impact of training on knowledge-based competencies among learners; and to compare the effects of two training conditions (self-guided digital training with or without coaching) in a nested parallel, two-arm, individually randomised controlled trial. Eligible participants were 18 or older; fluent in Hindi or English; able to access digital training; and had no prior experience of delivering structured psychotherapies. 277 participants were enrolled from 31 March 2022 to 19 June 2022 of which 230 (83%) completed the study. There was a significant increase in competency score from pre-training (Mean = 7.01, SD = 3.29) to post-training (Mean = 8.88, SD = 3.80), 6 weeks after the pre-training assessment. Knowledge competency scores showed larger increase among participants randomised to the coaching arm (AMD = 1.09, 95% CI 0.26–1.92, p = 0.01) with an effect size (d) of 0.33 (95% CI 0.08–0.58). More participants completed training in the coaching arm (n = 96, 69.6%) compared to the self-guided training arm (n = 56, 40.3%). In conclusion, a coach-supported remote digital training intervention is associated with enhanced participation by learners and increased psychotherapeutic knowledge competencies.