Interactions between Aquatic Plants and Cyanobacterial Blooms in Freshwater Reservoir Ecosystems

Climate change and nutrient pollution are echoed by worldwide increasing trends in the frequency, duration, and toxicity of cyanobacterial (blue-green algal) blooms. Therefore, searching for the best options to mitigate blooms is relevant and timely. Aquatic vascular plants offer a promising solution through biological control. In this study, we use reservoirs regularly affected by intensive blooms (the Kyiv and Kaniv Reservoirs of the Dnipro River, Ukraine) to investigate whether macrophytes may inhibit or reduce the massive development of cyanobacteria. Special attention was paid to plants with floating leaves and free-floating plants since data on their effects on cyanobacteria are controversial. On the basis of field and satellite observations, the spatial distribution of cyanobacterial blooms and aquatic macrophyte patches was assessed. Multispectral images captured by satellites Sentinel-2a (S2A) and Sentinel-2b (S2B) were used. In addition, based on data from field observations, a comparative analysis of phytoplankton and physical and chemical parameters between areas of the reservoirs overgrown and not overgrown by macrophytes was carried out. The obtained results indicate that in macrophyte patches phytoplankton structure differed from that observed in open waters. However, in areas of reservoirs dominated by floating-leaf plants or free-floating plants, a significant decrease in phytoplanktic or cyanobacterial biomass was not observed. This is most likely due to the fact that these macrophytes did not reduce the concentration of biogenic substances to a level that would limit cyanobacterial growth. On the contrary, intensive overgrowth of floating-leaf plants (in particular, Trapa natans) along the river sections of the reservoirs, as well as other factors, contributed to nitrogen and phosphorus enrichment. Therefore, in the face of relevant nutrient supply, these ecological groups of macrophytes (floating-leaf plants and free-floating plants) have not shown statistically significant effectiveness in controlling the process of cyanobacterial blooms in reservoir ecosystems

Association between mental health, psychological characteristics, and motivational functions of volunteerism among Polish and Ukrainian volunteers during the Russo-Ukrainian War

Abstract The Russo-Ukrainian War has led to a humanitarian crisis, and many people volunteered to help affected refugees. This cross-sectional survey study investigates the relationships between the psychological impact of participation, coping mechanisms, and motivational functions of volunteering during the Russo-Ukrainian War among 285 Ukrainian and 435 Polish volunteers (N = 720). Multivariate linear regression was used to examine relationships between motivational functions and psychosocial and demographic characteristics. Ukrainian volunteers reported significantly higher Hyperarousal and Avoidance, Depression, Anxiety, and Stress, Problem-focused, Emotion-focused, and Avoidant coping, as well as total scores of Hardiness and Psychological Capital than Polish counterparts. Linear regression analysis found that Impact of the Event Scale results, Coping with Stress, being a female, unemployed, and religious were significantly associated with higher motivational functions. Ukrainian volunteers could significantly reduce negative feelings and strengthen social networks and religious faith by volunteering, while Polish volunteers were significantly more likely to gain skills and psychosocial development from helping others