Effects of submerged vegetation on water clarity across climates

A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate lakes. Recent work suggests differences in biotic interactions between (sub)tropical and cooler lakes might result in a less pronounced clearing effect in the (sub)tropics. To assess whether the effect of submerged vegetation changes with climate, we sampled 83 lakes over a gradient ranging from the tundra to the tropics in South America. Judged from a comparison of water clarity inside and outside vegetation beds, the vegetation appeared to have a similar positive effect on the water clarity across all climatic regions studied. However, the local clearing effect of vegetation decreased steeply with the contribution of humic substances to the underwater light attenuation. Looking at turbidity on a whole-lake scale, results were more difficult to interpret. Although lakes with abundant vegetation (>30%) were generally clear, sparsely vegetated lakes differed widely in clarity. Overall, the effect of vegetation on water clarity in our lakes appears to be smaller than that found in various Northern hemisphere studies. This might be explained by differences in fish communities and their relation to vegetation. For instance, unlike in Northern hemisphere studies, we find no clear relation between vegetation coverage and fish abundance or their diet preference. High densities of omnivorous fish and coinciding low grazing pressures on phytoplankton in the (sub)tropics may, furthermore, weaken the effect of vegetation on water clarity

Knowledge, attitudes and practices of medical staff towards obesity management in patients with spinal cord injuries: an International survey of four western European countries

Objective: To (1) examine the opinions of medical staff working in spinal cord injury (SCI) centres (SCICs); (2) evaluate their knowledge, attitudes and practices towards obesity prevention and management; (3) report the number of beds and dietitians available at each SCIC. Methods: A 37-item questionnaire was sent to 23 SCICs in the UK, the Netherlands, Belgium and the Republic of Ireland between September 2012 and January 2013. Results: Eighteen SCICs returned the questionnaires for analysis. All respondents stated that they had an interest in obesity treatment but only 2.3% of the respondents received training in obesity management. Sixty-one percent of staff did not consider body mass index (BMI) to be appropriate for use in SCI patients and subsequently less than half of the respondents use BMI routinely. The majority of respondents reported that they are confident in dealing with overweight (74.5%) and obese (66.1%) SCI adults, less than half (44.1%) are confident in treating overweight and obese SCI children. Respondents also indicated the need for nationally adopted guidelines and a lack of physical activity provision. There were 17.5 whole-time equivalent (WTE) dietitians recorded in 22 SCICs, equivalent to 47.8 beds per WTE dietitians (range 10–420). Non-UK SCIC dietitians are significantly better resourced than in UK SCICs (beds per WTE dietitian: 36 vs 124, P=0.035). Conclusion: Medical staff expressed the need to participate in obesity prevention and management. Appropriate training should be considered for all medical staff and the development of specific weight management guidelines and dietetic provision should be considered

Early warning of climate tipping points from critical slowing down: comparing methods to improve robustness

We address whether robust early warning signals can, in principle, be provided before a climate tipping point is reached, focusing on methods that seek to detect critical slowing down as a precursor of bifurcation. As a test bed, six previously analysed datasets are reconsidered, three palaeoclimate records approaching abrupt transitions at the end of the last ice age and three models of varying complexity forced through a collapse of the Atlantic thermohaline circulation. Approaches based on examining the lag-1 autocorrelation function or on detrended fluctuation analysis are applied together and compared. The effects of aggregating the data, detrending method, sliding window length and filtering bandwidth are examined. Robust indicators of critical slowing down are found prior to the abrupt warming event at the end of the Younger Dryas, but the indicators are less clear prior to the Bølling-Allerød warming, or glacial termination in Antarctica. Early warnings of thermohaline circulation collapse can be masked by inter-annual variability driven by atmospheric dynamics. However, rapidly decaying modes can be successfully filtered out by using a long bandwidth or by aggregating data. The two methods have complementary strengths and weaknesses and we recommend applying them together to improve the robustness of early warnings

Foreseeing the future of mutualistic communities beyond collapse

International audienc

Language differences in qualitative research: is meaning lost in translation?

This article discusses challenges of language differences in qualitative research, when participants and the main researcher have the same non-English native language and the non-English data lead to an English publication. Challenges of translation are discussed from the perspective that interpretation of meaning is the core of qualitative research. As translation is also an interpretive act, meaning may get lost in the translation process. Recommendations are suggested, aiming to contribute to the best possible representation and understanding of the interpreted experiences of the participants and thereby to the validity of qualitative research

The Clumping Transition in Niche Competition: a Robust Critical Phenomenon

We show analytically and numerically that the appearance of lumps and gaps in the distribution of n competing species along a niche axis is a robust phenomenon whenever the finiteness of the niche space is taken into account. In this case depending if the niche width of the species $\sigma$ is above or below a threshold $\sigma_c$, which for large n coincides with 2/n, there are two different regimes. For $\sigma > sigma_c$ the lumpy pattern emerges directly from the dominant eigenvector of the competition matrix because its corresponding eigenvalue becomes negative. For $\sigma </- sigma_c$ the lumpy pattern disappears. Furthermore, this clumping transition exhibits critical slowing down as $\sigma$ is approached from above. We also find that the number of lumps of species vs. $\sigma$ displays a stair-step structure. The positions of these steps are distributed according to a power-law. It is thus straightforward to predict the number of groups that can be packed along a niche axis and it coincides with field measurements for a wide range of the model parameters.Comment: 16 pages, 7 figures; http://iopscience.iop.org/1742-5468/2010/05/P0500

Use of probiotics in preventing antibiotic associated diarrhoea and Clostridium difficile associated diarrhoea in spinal injury centres: An international survey of four western European countries

Probiotics may prevent antibiotic-associatedand Clostridium difficile-associated- diarrhoea (AAD/CDAD). Many spinal cord injury centres (SCICs) practitioners consider probiotics generically and may not realise that efficacy can be strain-, dose-, and disease-specific. One to four SCICs per country (depending on population size) were contacted (UK:4; the Netherlands:3; Belgium: I; Republic of Ireland: 1) to (a) determine if they stocked probiotics; (b) determine whether the use of those probiotics was evidence-based; and (c) document their C. difficile infection (CDI) practices. All nine SCICs responded to the survey (7 physicians, 3 microbiologists, 1 nurse and 2 dietitians). Five (55.5%) stocked probiotics; five different probiotics were identified. Four probiotics were preferred choice prevention o f AAD/CDAD were Lactobacillus casei Shirota (44.4%), L. casei D N -114001 (22.2%), L. acidophilus (22.2%) and a mixed-strains probiotic (Ecologic Pro-AD) (11.1%). Only one evidence base study was identified supporting the use of probiotic for prevention of AAD in SCI patients. Mean CDI cases per 10,000 patient-days were 0.307 (s.d: 0.486, range 0.00 to 1.08). Definitions of diarrhoea and CDI varied among SCICs. Stocking probiotics for the prevention of AAD / CDAD is not common. There is only one single study showing efficiency of a particular strain in SCI populations. The study highlighted the importance of using a standardised definition o f diarrhoea when conducting AAD/CDAD research