[1] Feedback between vegetation growth, water flow, and landform is important for the biogeomorphic evolution of many landscapes, such as tidal marshes, alluvial rivers, and hillslopes. While experimental studies often focus on flow reduction within static homogeneous vegetation, we concentrate on flow acceleration around and between dynamically growing vegetation patches that colonize an initially bare landscape, with specific application to Spartina anglica, a pioneer of intertidal flats. Spartina patches were placed in a large-scale flow facility of 16 × 26 m, simulating the growth of two vegetation patches by increasing the patch diameter (D = 1-3 m) and decreasing the interpatch distance (d = 2.3-0 m). We quantified that the amount of flow acceleration next to vegetation patches, and the distance from the patch where maximum flow acceleration occurs, increases with increasing patch size. In between the patches, the accelerated flow pattern started to interact as soon as D/d ≥ 0.43-0.67. As the patches grew further, the flow acceleration increased until D/d ≥ 6.67-10, from which the flow acceleration between the patches was suppressed, and the two patches started to act as one. These findings are in accordance with theory on flow around and between nonpermeable structures; however, the threshold D/d values found here for permeable vegetation patches are higher than those for nonpermeable structures. The reported flow interactions with dynamic vegetation patches will be essential to further understanding of the larger-scale biogeomorphic evolution of landscapes formed by flowing water, such as tidal flats, floodplain rivers, and hillslopes.

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Uranium (U) causes oxidative stress in Arabidopsis thaliana plants grown at pH 5.5. However, U speciation and its toxicity strongly depend on environmental parameters, for example pH. It is unknown how different U species determine U uptake and translocation within plants and how they might affect the oxidative defense mechanisms of these plants. The present study analyzed U uptake and oxidative stress-related responses in A. thaliana (Columbia ecotype) under contrasted U chemical speciation conditions. The 18-d-old seedlings were exposed for 3 d to 25 µM U in a nutrient solution of which the pH was adjusted to 4.5, 5.5, 6.5, or 7.5. Results indicate that there is a different rate of U uptake and translocation at the different pHs, with high uptake and low translocation at low pH and lower uptake but higher translocation at high pH. After U exposure, an increased glutathione reductase activity and total glutathione concentration were observed in U-exposed roots, pointing toward an important role for glutathione in the root defense system against U either by chelation or by antioxidative defense mechanisms. In leaves, antioxidative defense mechanisms were activated on U exposure, indicated by increased superoxide dismutase and catalase activity. As it seems that U toxicity is influenced by pH, it is important to consider site-specific characteristics when making U risk assessments.

BackgroundIn the past few years, the use of social media has gradually become an important part of our daily lives. While some might see this as a threat to our productivity or as a source of procrastination, social media as a whole have unquestionably changed the way in which information and knowledge disseminate in our society.Social media guideThis article is meant to serve as a guide for scientists who would like to establish their online presence and includes an outline of the benefits of using social media as well as strategies for establishing and improving your presence in social media. Environmental scientists in particular can benefit enormously from this approach, since this field of science deals with topics that directly impact our daily lives.Case studyTo highlight these approaches for our fellow scientists in the field of environmental science and toxicology and in order to better engage with our own peers, we describe the outreach methods used by the student advisory councils of the Society of Environmental Toxicology and Chemistry (SETAC) and how we have worked towards an improved social media presence. In this article we present our initiatives to increase social media usage and engagement within SETAC. This includes joint social media accounts organized by the SETAC student advisory councils from various SETAC geographical units. We also led a course on social media usage at the SETAC Nashville meeting in 2013 and are currently developing other outreach platforms, including high school student-oriented science education blogs.ConclusionThe Students of SETAC will continue to increase communication with and among SETAC students on a global level and promote the use of social media to communicate science to a wide variety of audiences.

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HighlightsMigration is effective in compensating for vole deaths at high levels of radiation exposure.Long term effects simulated include a small historic dose component.Adaptation can account for low dose radio-hypersensitivity and increased radio-resistance.Current radiation dose assessment benchmarks are protective for the modelled vole population.