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.

Impact of cognitive rehabilitation therapy on neuropsychological impairments as measured by brain perfusion SPECT: a longitudinal study

Three patients, with known brain injury and neuropsychological impairments, are followed through an individualized cognitive rehabilitation programme and post discharge from the treatment programme. Single Photon Emission Computed Tomography (SPECT) of the brain was employed to evaluate resting relative cerebral blood flow (rCBF) during the process of recovery from brain injury. All patients experienced significant improvements on measures of neuropsychological functioning and improvements in rCBF during this longitudinal study. The specific changes in rCBF appear to be related to the location of the patient's brain injury and strategies particular to cognitive rehabilitation therapy. Continued improvements in rCBF, functional abilities, and cognitive skills were documented in these three cases up to 45 months post brain injury.