Phytoplankton community responses in a shallow lake following lanthanum-bentonite application.

The release of phosphorus (P) from bed sediments to the overlying water can delay the recovery of lakes for decades following reductions in catchment contributions, preventing water quality targets being met within timeframes set out by environmental legislation (e.g. EU Water Framework Directive: WFD). Therefore supplementary solutions for restoring lakes have been explored, including the capping of sediment P sources using a lanthanum (La)-modified bentonite clay to reduce internal P loading and enhance the recovery process. Here we present results from Loch Flemington where the first long-term field trial documenting responses of phytoplankton community structure and abundance, and the UK WFD phytoplankton metric to a La-bentonite application was performed. A Before-After-Control-Impact (BACI) analysis was used to distinguish natural variability from treatment effect and confirmed significant reductions in the magnitude of summer cyanobacterial blooms in Loch Flemington, relative to the control site, following La-bentonite application. However this initial cyanobacterial response was not sustained beyond two years after application, which implied that the reduction in internal P loading was short-lived; several possible explanations for this are discussed. One reason is that this ecological quality indicator is sensitive to inter-annual variability in weather patterns, particularly summer rainfall and water temperature. Over the monitoring period, the phytoplankton community structure of Loch Flemington became less dominated by cyanobacteria and more functionally diverse. This resulted in continual improvements in the phytoplankton compositional and abundance metrics, which were not observed at the control site, and may suggest an ecological response to the sustained reduction in filterable reactive phosphorus (FRP) concentration following La-bentonite application. Overall, phytoplankton classification indicated that the lake moved from poor to moderate ecological status but did not reach the proxy water quality target (i.e. WFD Good Ecological Status) within four years of the application. As for many other shallow lakes, the effective control of internal P loading in Loch Flemington will require further implementation of both in-lake and catchment-based measures. Our work emphasizes the need for appropriate experimental design and long-term monitoring programmes, to ascertain the efficacy of intervention measures in delivering environmental improvements at the field scale.

[Anesthesia and intensive care of subarachnoid hemorrhage. A survey on practice in 32 centres]. / Anesthésie-réanimation de l'hémorragie sous-arachnoïdienne. Enquête sur les pratiques de 32 centres.

OBJECTIVE: To assess the current practices in anaesthesia and intensive care in patients experiencing subarachnoid haemorrhage (SAH). STUDY DESIGN: Analysis of questionnaire sent to the members of the French speaking Association of neuroanesthesia and intensive care. METHODS: The survey, performed in the summer of 1995, included questions on the composition of the neuroanesthesia team, anaesthesia, as well as medical and surgical treatments. RESULTS: Twenty-nine French and three non French centers answered the questionnaire. In 14 centers, more than 60 SAH had been treated in the previous year. Angiography was performed under sedation with a benzodiazepine associated with an opioid (54%). Criteria for choosing an endovascular approach were the site of the aneurysm (81%), its neck size (42%) and the underlying disease (42%). Anaesthesia was induced with either propofol (60%) or thiopentone (40%) associated with an opioid and a muscle relaxant. It was maintained with either isoflurane (59%) or propofol (41%). Nitrous oxide was often associated (62%). During anaesthesia, nimodipine (84%), mannitol (69%), anticonvulsants (47%), dopamine (31%) and lidocaine (9%) were also administered. Postoperatively, nimodipine was administered for prophylaxis of vasospasm (97%) and transcranial Doppler was employed to diagnose vasospasm (50%). Other techniques of care included hypervolaemia (89%), controlled arterial hypertension (36%) and haemodilution (36%).