Accelerated recovery of lake macroinvertebrates in the third decade since the reversal of acidification.

Chemical reversal from acidification has been progressing in European freshwaters since the late 1980s, responding to successful control of atmospheric pollution by acidifying emissions. However, biological recovery is often delayed after improvements in water composition. We studied macroinvertebrate recovery from acidification in eight glacial lakes in the Bohemian Forest (central Europe) between 1999 and 2019. The chemical composition of these lakes reflects a complex of environmental changes, dominated by a very steep decline in acid deposition and, currently, by elevated nutrient leaching following climate-induced tree dieback within their catchments. Temporal trends in species richness, abundance, species traits and community composition were evaluated with regard to water chemistry, littoral habitat properties and fish colonisation. The results showed accelerated recovery of macroinvertebrates following two decades of gradual improvement in water composition and slowly progressing biological rehabilitation. We observed a significant increase in macroinvertebrate species richness and abundance, coupled with distinct changes in community composition, the extent of changes varying between lakes, reflecting different littoral habitat properties (vegetated vs. stony) and water chemistry. Overall, the communities shifted toward more specialised (grazers, filterers, and phytophilous species) and acid-tolerant taxa at the expense of detritivorous, eurytopic and acid-resistant taxa. Where fish reappeared, open-water taxa declined greatly. Compositional changes were likely driven by the combined effects of water chemistry reversal, rehabilitation of habitat conditions and fish colonisation. Despite favourable trends, communities in recovering lakes still lack several biotic elements, particularly less vagile, acid-sensitive taxa and specialised herbivores known from the regional species pool. It is expected that future progress in lake recovery will be further promoted or inhibited by stochastic colonisation or disturbance events.

[Prolonged culture in a humid chamber increases the yields of pathogenic bacteria from the respiratory tract samples of patients suffering from cystic fibrosis].

Current standards of care for cystic fibrosis (CF) patients lack unequivocal recommendations concerning the duration of primary culture of bacteriological samples. With the exception of Burkholderia cepacia (5 days), the minimum recommended duration of primary culture varies between 48 and 72 hours. Our aim was to evaluate the effect of an extended 10-day period of primary culture in a humid chamber in samples acquired from the respiratory tract of patients suffering from CF. Compared to standard culture, prolonged culture in a humid chamber yielded 1.85 times more isolates of pathogenic species in pharyngeal swabs (76 versus 41 isolates) and 1.4 times more isolates in sputum samples (116 versus 82), but only 1.14 times more isolates in nasal swabs (25 versus 22). Prolonged culture was most beneficial for Achromobacter spp. (6 versus 0), Stenotrophomonas maltophilia (16 versus 5) and Pseudomonas aeruginosa (69 versus 49), whereas there was little or no benefit at all for Staphylococcus aureus (87 versus 73) and Moraxella catarrhalis (10 versus 10). Therefore, prolonged culture in a humid chamber may definitely be recommended for pharyngeal swabs and sputum samples obtained from patients suffering from CF to achieve the maximum recovery rate of pathogenic bacteria, in particular non-fermenting Gram-negative rods.