Changes in microphytobenthos fluorescence over a tidal cycle: implications for sampling designs

Intertidal microphytobenthos (MPB) are important primary producers and provide food for herbivores in soft sediments and on rocky shores. Methods of measuring MPB biomass that do not depend on the time of collection relative to the time of day or tidal conditions are important in any studies that need to compare temporal or spatial variation, effects of abiotic factors or activity of grazers. Pulse amplitude modulated (PAM) fluorometry is often used to estimate biomass of MPB because it is a rapid, non-destructive method, but it is not known how measures of fluorescence are altered by changing conditions during a period of low tide. We investigated this experimentally using in situ changes in minimal fluorescence (F) on a rocky shore and on an estuarine mudflat around Sydney (Australia), during low tides. On rocky shores, the time when samples are taken during low tide had little direct influence on measures of fluorescence as long as the substratum is dry. Wetness from wave-splash, seepage from rock pools, run-off, rainfall, etc., had large consequences for any comparisons. On soft sediments, fluorescence was decreased if the sediment dried out, as happens during low-spring tides on particularly hot and dry days. Surface water affected the response of PAM and therefore measurements used to estimate MPB, emphasising the need for care to ensure that representative sampling is done during low tide

Social factors influencing Russian male alcohol use over the life course: a qualitative study investigating age based social norms, masculinity, and workplace context

The massive fluctuations occurring in Russian alcohol-related mortality since the mid-1980s cannot be seen outside of the context of great social and economic change. There is a dearth of qualitative studies about Russian male drinking and especially needed are those that address social processes and individual changes in drinking. Conducted as part of a longitudinal study on men’s alcohol consumption in Izhevsk, this qualitative study uses 25 semi-structured biographical interviews with men aged 33–60 years to explore life course variation in drinking. The dominant pattern was decreasing binge and frequent drinking as men reached middle age which was precipitated by family building, reductions in drinking with work colleagues, and health concerns. A minority of men described chaotic drinking histories with periods of abstinence and heavy drinking. The results highlight the importance of the blue-collar work environment for conditioning male heavy drinking in young adulthood through a variety of social, normative and structural mechanisms. Post-Soviet changes had a structural influence on the propensity for workplace drinking but the important social function of male drinking sessions remained. Bonding with workmates through heavy drinking was seen as an unavoidable and essential part of young men’s social life. With age peer pressure to drink decreased and the need to perform the role of responsible breadwinner put different behavioural demands on men. For some resisting social pressure to drink became an important site of self-determination and a mark of masculine maturity. Over the lifetime the place where masculine identity was asserted shifted from the workplace to the home, which commonly resulted in a reduction in drinking. We contribute to existing theories of Russian male drinking by showing that the performance of age-related social roles influences Russian men’s drinking patterns, drinking contexts and their attitudes. Further research should be conducted investigating drinking trajectories in Russian men

Growth form defines physiological photoprotective capacity in intertidal benthic diatoms

International audienceIn intertidal marine sediments, characterized by rapidly fluctuating and often extreme lightconditions, primary production is frequently dominated by diatoms. We performed a comparativeanalysis of photophysiological traits in 15 marine benthic diatom species belonging to the fourmajor morphological growth forms (epipelon (EPL), motile epipsammon (EPM-M) and non-motileepipsammon (EPM-NM) and tychoplankton (TYCHO)) found in these sediments. Our analysesrevealed a clear relationship between growth form and photoprotective capacity, and identified fastregulatory physiological photoprotective traits (that is, non-photochemical quenching (NPQ) and thexanthophyll cycle (XC)) as key traits defining the functional light response of these diatoms. EPMNMand motile EPL showed the highest and lowest NPQ, respectively, with EPM-M showingintermediate values. Like EPL, TYCHO had low NPQ, irrespective of whether they were grown inbenthic or planktonic conditions, reflecting an adaptation to a low light environment. Our resultsthus provide the first experimental evidence for the existence of a trade-off between behavioural(motility) and physiological photoprotective mechanisms (NPQ and the XC) in the four majorintertidal benthic diatoms growth forms using unialgal cultures. Remarkably, although motilityis restricted to the raphid pennate diatom clade, raphid pennate species, which have adopted anon-motile epipsammic or a tychoplanktonic life style, display the physiological photoprotectiveresponse typical of these growth forms. This observation underscores the importance of growthform and not phylogenetic relatedness as the prime determinant shaping the physiologicalphotoprotective capacity of benthic diatoms