Bioaerosols and atmospheric ice nuclei in a Mediterranean dryland: community changes related to rainfall

Certain biological particles are highly efficient ice nuclei (IN), but the actual contribution of bioparticles to the pool of atmospheric IN and their relation to precipitation are not well characterized. We investigated the composition of bioaerosols, ice nucleation activity, and the effect of rainfall by metagenomic sequencing and freezing experiments of aerosol samples collected during the INUIT 2016 campaign in a rural dryland on the eastern Mediterranean island of Cyprus. Taxonomic analysis showed community changes related to rainfall. For the rain-affected samples, we found higher read proportions of fungi, particularly of Agaricomycetes, which are a class of fungi that actively discharge their spores into the atmosphere in response to humidity changes. In contrast, the read proportions of bacteria were reduced, indicating an effective removal of bacteria by precipitation. Freezing experiments showed that the IN population in the investigated samples was influenced by both rainfall and dust events. For example, filtration and heat treatment of the samples collected during and immediately after rainfall yielded enhanced fractions of heat-sensitive IN in the size ranges larger than 5 µm and smaller than 0.1 µm, which were likely of biological origin (entire bioparticles and soluble macromolecular bio-IN). In contrast, samples collected in periods with dust events were dominated by heat-resistant IN active at lower temperatures, most likely mineral dust. The DNA analysis revealed low numbers of reads related to microorganisms that are known to be IN-active. This may reflect unknown sources of atmospheric bio-IN as well as the presence of cell-free IN macromolecules that do not contain DNA, in particular for sizes < 0.1 µm. The observed effects of rainfall on the composition of atmospheric bioaerosols and IN may influence the hydrological cycle (bioprecipitation cycle) as well as the health effects of air particulate matter (pathogens, allergens).

Sociocultural determinants of reproductive behaviour of ethnic groups

The article is devoted to consideration of sociocultural determinants of reproductive behavior of ethnic groups. Sociocultural determinants are those conditions (circumstances) that affect the nature of reproductive behavior of ethnic groups. These include social, economic and worldview factors. Depending on how the culture of ethnic community changes, the content of these factors changes. The gender and regional dimension is important in this case.

Vegetation community changes in response to phragmites management at Times Beach, Buffalo, New York

Management of invasive phragmites (Phragmites australis [Cav.] Trin. Ex Steud.) in the United States has proven challenging over the last several decades. Various methods for control exist, but integrated approaches appear to have the most success. However, documentation of vegetation community–wide responses to these approaches remains limited. This study monitored plant community changes at Times Beach, New York, over a five-year period. In concert with mowing and thatch removal in all areas, the study evaluated two herbicides separately and together, representing three experimental treatment areas (TAs), for control efficacy by measuring plant community structure. Phragmites was targeted for treatments, avoiding native and nonproblematic non-native species when possible, to preserve beneficial habitat during phragmites control efforts. Monitoring results showed significant drops in phragmites relative cover, relative frequency, and importance values due to integrated management, regardless of herbicide treatment, with corresponding increases in these same values for native and other plant species. This suggests that prudent removal of phragmites is compatible with beneficial plant restorative efforts to maintain and improve habitat in infested areas.