Recent advances in understanding and measurement of mercury in the environment: Terrestrial Hg cycling

This review documents recent advances in terrestrial mercury cycling. Terrestrial mercury (Hg) research has matured in some areas, and is developing rapidly in others. We summarize the state of the science circa 2010 as a starting point, and then present the advances during the last decade in three areas: land use, sulfate deposition, and climate change. The advances are presented in the framework of three Hg "gateways" to the terrestrial environment: inputs from the atmosphere, uptake in food, and run off with surface water. Among the most notable advances:The Arctic has emerged as a hotbed of Hg cycling, with high stream fluxes and large stores of Hg poised for release from permafrost with rapid high-latitude warming.The bi-directional exchange of Hg between the atmosphere and terrestrial surfaces is better understood, thanks largely to interpretation from Hg isotopes; the latest estimates place land surface Hg re-emission lower than previously thought.Artisanal gold mining is now thought responsible for over half the global stream flux of Hg.There is evidence that decreasing inputs ofHg to ecosystems may bring recovery sooner than expected, despite large ecosystem stores of legacy Hg.Freshly deposited Hg is more likely than stored Hg to methylate and be incorporated in rice.Topography and hydrological connectivity have emerged as master variables for explaining the disparate response of THg and MeHg to forest harvest and other land disturbance.These and other advances reported here are of value in evaluating the effectiveness of theMinamata Convention on reducing environmental Hg exposure to humans and wildlife. (C) 2020 The Authors. Published by Elsevier B.V

Venous ulcers associated with superficial venous insufficiency

A 59-year-old female secretary was referred for evaluation and treatment of a non-healing painful ulcer on the medial aspect of her right lower leg. The ulcer had been recurrent almost every year for the past 9 years, often healing during the winter season. She had since early childhood been overweight (currently 87 kg, 170 cm, body mass index 30) and had difficulty in using compression stocking. She was otherwise healthy. She had two children, the first child born when she was 32 year of age and her second child 2 years later. After the birth of her second child she began to notice varicose veins on the lower leg on both sides and she often felt tiredness and heaviness in the leg in the afternoon. There was no history of deep venous thrombosis. She had been on birth control pills for 10 years and was currently on hormone replacement therapy because of severe postmenopausal symptoms. She had been treated at a local dermatological clinic for the past 2 years and was now being evaluated by a vascular surgeon. Clinical evaluation showed that she had 5 × 5 cm well-granulated ulceration above the right median malleolus which was surrounded by brownish leathery skin. She had slight swelling of the right leg with large varicosities below the knee. The left leg had large varicosities below the knee but no swelling or skin changes. Doppler examination revealed clear reflux in the groin that could be followed over both great saphenous veins (GSV) down the thigh. A possible minimal reflux was also noted in the popliteal fossa on the right side, although it was difficult to confirm this when the Doppler examination was repeated. Foot arteries were palpable on the dorsum of the foot on both sides

Trophically Unique Species Are Vulnerable to Cascading Extinction

Understanding which species might become extinct and the consequences of such loss is critical. One consequence is a cascade of further, secondary extinctions. While a significant amount is known about the types of communities and species that suffer secondary extinctions, little is known about the consequences of secondary extinctions for biodiversity. Here we examine the effect of these secondary extinctions on trophic diversity, the range of trophic roles played by the species in a community. Our analyses of natural and model food webs show that secondary extinctions cause loss of trophic diversity greater than that expected from chance, a result that is robust to variation in food web structure, distribution of interactions strengths, functional response, and adaptive foraging. Greater than expected loss of trophic diversity occurs because more trophically unique species are more vulnerable to secondary extinction. This is not a straightforward consequence of these species having few links with others but is a complex function of how direct and indirect interactions affect species persistence. A positive correlation between a species’ extinction probability and the importance of its loss defines high‐risk species and should make their conservation a priority

Cochlear implants before 9 months of age led to more natural spoken language development without increased surgical risks

Aim Evidence suggests that cochlear implants are beneficial for language development, but there is no consensus about the ideal age for surgery. We investigated how language development and surgical safety were affected by patients’ ages. Methods This study comprised 103 children (52 boys) aged 4.3‐16 years who received cochlear implants at 5‐29 months at the Karolinska University Hospital, Stockholm, Sweden, between 2002 and 2013. All showed typical development and were from monolingual homes. Bilateral implants were common (95%). The children were regularly assessed on language understanding, vocabulary and speech recognition by a multi‐disciplinary team for 10.0 ± 3.7 (4.7‐16.0) years. Results There were no associations between complications after surgery and the age when children had their first implant. Children implanted at 5‐11 months reached an age‐equivalent level of language understanding and better vocabulary outcome sooner than subgroups implanted later. Children who had surgery at 12‐29 months demonstrated more atypical and delayed language abilities over time. Early implantation, preferably before 9 months, may lead to a more typical trajectory of spoken language development. Conclusion Our findings showed that cochlear implantation before 9 months was safe. Early implantation may reduce the negative effects of auditory deprivation and promotes more natural and synchronised language development

The importance of species interactions in eco-evolutionary community dynamics under climate change

Eco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes. Understanding the dynamics of species interactions can help predict community responses to climate change. A spatially explicit model finds that species interactions and competition mitigate the harmful impacts of climate change, and that temperature-dependent competition makes communities more variable and responsive to changing climates.Funding Agencies|Swedish Research CouncilSwedish Research CouncilEuropean Commission [FORMAS 2015-01262, VR 2017-05245]</p

Robustness to secondary extinctions: Comparing trait-based sequential deletions in static and dynamic food webs

Number of words in manuscript: 6768 Number of words in abstract: 260 Number of words in title: 14 Curtsdotter et al. Basic and Applied Ecology 2 Abstract The loss of species from ecological communities can unleash a cascade of secondary extinctions, the risk and extent of which are likely to depend on the traits of the species that are lost from the community. To identify species traits that have the greatest impact on food web robustness to species loss we here subject allometrically scaled, dynamical food web models to several deletion sequences based on species&apos; connectivity, generality, vulnerability or body mass. Further, to evaluate the relative importance of dynamical to topological effects we compare robustness between dynamical and purely topological models. This comparison reveals that the topological approach overestimates robustness in general and for certain sequences in particular. Top-down directed sequences have no or very low impact on robustness in topological analyses, while the dynamical analysis reveals that they may be as important as high-impact bottom-up directed sequences. Moreover, there are no deletion sequences that result, on average, in no or very few secondary extinctions in the dynamical approach. Instead, the least detrimental sequence in the dynamical approach yields an average robustness similar to the most detrimental (non-basal) deletion sequence in the topological approach. Hence, a topological analysis may lead to erroneous conclusions concerning both the relative and the absolute importance of different species traits for robustness. The dynamical sequential deletion analysis shows that food webs are least robust to the loss of species that have many trophic links or that occupy low trophic levels. In contrast to previous studies we can infer, albeit indirectly, that secondary extinctions were triggered by both bottom-up and topdown cascades