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Background and aims Mangrove species respond to variation in soil bulk density (BD). However, very little is known about the regulatory mechanisms that trigger these responses. Methods Endogenous concentrations of different phytohormones were measured in the roots of two mangrove species (Avicennia marina and Rhizophora stylosa) grown in low and high BD soils. The potential involvement of ethylene in regulating plant growth responses was tested by applying the ethylene biosynthesis inhibitors cobalt chloride (CoCl2) and aminoisobutyric acid (AIB). Results The two mangrove species responded differently to variation in soil BD. High BD decreased root growth of R. stylosa, but not A. marina. Soil BD had no effect on root phytohormone levels in R. stylosa, but loose soils increased 1-aminocyclopropane-1-carboxylic acid whilst decreasing salicylic acid and gibberellin in A. marina. Applying ethylene inhibitors enhanced R. stylosa root growth, while increasing indole-3-acetic acid but decreasing isopentenyl adenine levels. In contrast, AIB inhibited A. marina root growth, while increasing trans-zeatin levels. Ethylene inhibitors affected salicylic acid levels in both species. Conclusion Salicylic acid is central to root growth responses to variation in BD in A. marina. Conversely, the interaction of ethylene and gibberellin drives responses in R. stylosa. Hormonal interactions involving ethylene potentially reflect the adaptations of the two species to differing conditions within the intertidal zone, with A. marina behaving like an aquatic species and R. stylosa behaving like a terrestrial species.

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Conceptual models have described mangrove forest structure in response to tidal inundation, porewater salinity and mangrove water use, however, the importance of feedbacks have not been assessed. We assessed the processes underlying the feedback between water availability and plant water use in mangrove ecosystems by applying the process- and individual-based mangrove model MANGA, evaluating individual tree growth behavior, emerging forest structure, and mangrove species composition. We compared simulation data with field data collected at a field site with a monospecific mangrove forest that showed a strong gradient in tree height and biomass across the intertidal zone. While tidal inundation and the resulting porewater salinity gradient caused variation in mangrove forest structure within the MANGA model, the inclusion of tree water use in the model led to high similarity between model results and field observations. We further show the importance of the feedback between tree water use and porewater salinity for emergence of species zonation patterns. In accordance with particular site observations, we simulated the response to a broad spectrum of modelled porewater salinity inputs of an artificial forest. The modelled forest consists of two distinct species differing in their water use efficiency and salt tolerance. The modelled feedback mechanism produced a strong correlation between mangrove species zonation along the intertidal gradient and porewater salinity inputs at the system boundaries. The results of this study describe and demonstrate the absolute and relative importance of the implemented interacting processes on mangrove vegetation patterns. A better understanding of the role of tidal inundation and the feedback loops between plant water use and porewater salinity in determining mangrove forest structure will help to predict and manage the fate of mangrove ecosystems in a changing climate.

Plant–soil feedbacks are important as they provide valuable insights into ecosystem dynamics and ecosystems stability and resilience against multiple stressors and disturbances, including global climate change. In mangroves, plant–soil feedbacks are important for ecosystem resilience in the face of sea level rise, carbon sequestration, and to support successful ecosystem restoration. Despite the recognition of the importance of plant–soil feedbacks in mangroves, there is limited empirical data available. We reviewed empirical studies from mangrove ecosystems and evaluate numerical models addressing plant–soil feedbacks. The empirical evidence suggests that plant–soil feedbacks strongly influence ecological processes (e.g. seedling recruitment and soil elevation change) and forest structure in mangrove ecosystems. Numerical models, which successfully describe plant–soil feedbacks in mangrove and other ecosystems, can be used in future empirical studies to test mechanistic understanding and project outcomes of environmental change. Moreover, the combination of both, modelling and empirical approaches, can improve mechanistic understanding of plant–soil feedbacks and thereby ecosystem dynamics in mangrove ecosystems. This combination will help to support sustainable coastal management and conservation.

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Australia's tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia's tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha(-1) (range 14-963 Mg OC ha(-1)). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha(-1) yr(-1). Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia's 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr(-1), with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

Mangroves are valuable coastal habitats that are globally under pressure due to climate change and coastal development. Small-scale physical disturbance by tidal inundation and wave-induced sediment dynamics has been described as the main bottlenecks to mangrove seedling establishment on exposed tidal flats. However, such biophysical bottlenecks remain poorly studied.Mangrove progradation at our study site at the Firth of Thames (New Zealand) has been described as rapid but disturbance limited. For this site, we apply a mechanistic model according to the ‘Window of Opportunity’ (WoO) concept, which analyses real time series of external forcing for disturbance free periods. The model was parameterized with manipulative experiments on seedling stability and monitoring data. The modelled inundation free periods for initial anchoring were validated by a caging experiment with loose and tethered propagules.Although the time series of external forcing derived from monitoring data are simplified, our model confirms the absence of mangrove progradation due to failed recruitment events on the tidal flat since 1997. The model also shows, that a temporary reduction in external forcing would lead to a sudden progradation of the mangrove forest.WoO dynamics, where vegetation establishment requires temporarily benign conditions, may be of general importance to other ecosystems with stochastic external forcing. Understanding the biophysical interactions between vegetation and geomorphic processes is key to better manage and protect disturbance-driven ecosystems in times of changing wind pattern and accelerated sea-level rise.

Item does not contain fulltext, Spontaneous (non-traumatic) intracerebral haemorrhage (ICH) has a high case-fatality and leaves many survivors disabled. Clinical characteristics and outcome seem to vary according to the cause of ICH, but population-based comparisons are scarce. We studied two prospective, population-based cohorts to determine differences in outcome [case-fatality and modified Rankin Scale (mRS)] after incident ICH due to brain arteriovenous malformations (AVM) [Scottish Intracranial Vascular Malformation Study (SIVMS), n = 90] and spontaneous ICH [Oxford Vascular Study (OXVASC), n = 60]. Patients with AVM-ICH were younger, had lower pre-stroke and admission blood pressure (BP), higher admission Glasgow Coma Scale (GCS) and were more likely to have an ICH in a lobar location than patients with spontaneous ICH (sICH). Case fatality throughout 2-year follow-up was greater following sICH than AVM-ICH [34/56 (61%) versus 11/90 (12%) at 1 year, odds ratio (OR) 11 (95% Confidence Interval (CI) 5-25)], as was death or dependence (mRS >or= 3) [40/48 (83%) versus 26/65 (40%) at 1 year, OR 8 (3-19)]. Differences in outcome persisted following stratification by age and sensitivity analyses. In multivariable analyses of 1 year outcome, independent predictors of death were sICH (OR 21, 4-104) and increasing ICH volume (OR 1.03, 1.01-1.05), and independent predictors of death or dependence were sICH (OR 11, 2-62) and GCS on admission (OR 0.79, 0.67-0.93). Outcome after AVM-ICH is better than after sICH, independent of patient age and other known predictors of ICH outcome.

Saderne, V., Geraldi, N. R., Macreadie, P. I., Maher, D. T., Middelburg, J. J., Serrano, O., ... & Fourqurean, J. W. (2019). Role of carbonate burial in Blue Carbon budgets. Nature communications, 10(1), 1106. Available here