Dynamics of microbiotic patterns reveal surface water groundwater interactions in intermittent and perennial streams.

Exchange between groundwater (GW), hyporheic zone waters (HZ) and surface waters (SW) is critical for water quality, quantity, and the ecological health and functioning of all three ecosystems. Hydrological exchange is particularly important in intermittent creeks, such as in the Murray Darling Basin, Australia, where stream reaches shift from losing to gaining depending on the volume of surface flows. In this study we used hydrochemistry to identify SW-GW exchange and combined this with eDNA data to analyse the response of eukaryote and prokaryote communities to differing flow conditions within intermittent and perennial stream reaches. Our study suggested that SW and GW microbial communities were only around 30% similar. Differences in microbiota between SW, HZ and GW habitats were driven by changes in relative abundances of surface water dominant organisms (such as those capable of photosynthesis) as well as anaerobic taxa typical of GW environments (e.g., methanogens), with GW and HZ microbial communities becoming increasingly different to those in SW as flow ceased in intermittent creeks. Fine-scale hydrologic changes were identified through microbial communities in the perennial Maules Creek, indicating the importance of GW-SW exchange to biotic communities. This study highlights the importance of flow in shaping microbial communities and biogeochemical cycling within intermittent creeks and their connected alluvial aquifers. Our results suggest that microbiota may prove a useful indicator of SW-GW exchange, and in some circumstances, may be more sensitive in demonstrating fine-scale changes in SW-GW interactions than water chemistry. This knowledge furthers our understanding of GW-SW exchange and its impacts on ecological health.

Cryptic speciation in two widespread subterranean amphipod genera reflects historical drainage patterns in an ancient landscape.

The landscape of the Pilbara region of Western Australia has been relatively unchanged for 100 million years. The ancient river systems of this region might be expected to be sources of isolation and divergence for aquatic species. Hence, the occurrence of widespread groundwater taxa in this landscape offers the opportunity to examine associations between genetic diversity and drainage patterns. Pilbarus and Chydaekata are two widespread genera of subterranean amphipods endemic to the Pilbara, each occupying multiple tributaries. We used molecular data to examine the roles of drainage patterns in structuring genetic diversity. Gene flow within a tributary may be facilitated by the occasional occurrence of these amphipods in springs, which results in their downstream dispersal during episodic flooding. However, tributary boundaries may form hydrological barriers to gene flow, resulting in localised isolation of populations and divergence. Samples of both genera, collected throughout three river basins, were examined for sequence divergence in the cytochrome c oxidase I mitochondrial gene. There was no evidence of contemporary gene flow among populations of either genus, and each tributary contained highly divergent lineages, which were not associated with similar morphological differentiation. This suggests cryptic speciation has occurred, and similar phylogenetic signals in both taxa imply similar evolutionary histories. Surface populations may have been driven into subterranean refugia by the cessation of flow in the rivers, associated with Tertiary climate change, while morphological evolution may have been constrained by stabilising selection. The lack of congruence between molecular diversity and morphology raises important practical issues for conservation.

[Powerlessness and apathy in digitalis intoxication]. / Adynamie und Apathie bei Digitalisintoxikation.

A 85 year old female was hospitalized because of a bronchopulmonary infection. During the hospitalization she developed a progressive stupor. There was no sign of an intracerebral pathology, an electrolyte disorder, a new infection or a psychiatric diagnosis. Evaluation of the past history made a recently started digitalis medication responsible for the stupor. After discontinuation of digitalis the patient regained complete consciousness within two weeks. In the Holter-EKG we found once an asystole of four seconds duration without any symptoms.

[Magnetic resonance tomography in osteoid osteoma: more confusion than benefit?]. / Magnetresonanztomographie beim Osteoid-Osteom: mehr Verwirrung als Nutzen?

The purpose of this evaluation was the description of potentially misleading MR appearances of osteoid osteoma. The MR images of 10 patients with osteoid osteoma were retrospectively evaluated and compared to radiographic, intraoperative and histologic findings. 4 of the 10 abnormalities were located in the proximal femur, two in the lumbar spine, and one each in the tibial plateau, in the cervical spine, in the sacrum and in the first metacarpal. 8 of the 9 nidi visible on standard radiographs and/or CT scans were demonstrated on MR images. Edema was visible within the bone marrow in 3, within soft tissue in 2 and in both locations in 4 MR examinations. The soft tissue abnormalities were circumscribed in 3 patients and could be misdiagnosed as soft tissue tumors or an abscess in these patients. One of 5 osteoid osteomas located in the proximity of a joint mimicked septic arthritis. The MR appearance of osteoid osteoma may be misleading. However, false diagnoses usually can be avoided with a careful search of a nidus. MR imaging in osteoid osteoma is important for differential diagnosis.