David T. Welsh results 26
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Organic matter accumulation drives methylotrophic methanogenesis and microbial ecology in a hypersaline coastal lagoonNARA Subscribed
Hypersalinity is common in coastal wetlands throughout warm, tropical, and arid regions. Climate‐induced changes in rainfall, sea level, and anthropogenic modification to basins and coastlines are likely to further increase salinization in these ecosystems. Yet, carbon cycling in hypersaline coastal wetlands is not well understood, and poorly constrained in climate models. In the Coorong, a eutrophic, hypersaline coastal lagoo...
Assessing the linkage between breeding and non-breeding areas has important implications for understanding the fundamental biology of and conserving animal species. This is a challenging task for marine species, and in sea turtles a combination of stable isotope analysis (SIA) and satellite telemetry has been increasingly used. The Northwest Atlantic (NWA) loggerhead ( Caretta caretta ) Regional Management Unit, one of the lar...
Prolonging survival in good health is a fundamental societal goal. However, the leading determinants of disability-free survival in healthy older people have not been well established. Data from ASPREE, a bi-national placebo-controlled trial of aspirin with 4.7 years median follow-up, was analysed. At enrolment, participants were healthy and without prior cardiovascular events, dementia or persistent physical disability. Disab...
Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severityNARA Subscribed
The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the pr...
Denitrification, anammox, and dissimilatory nitrate reduction to ammonium across a mosaic of estuarine benthic habitatsNARA Subscribed
Estuaries play a key role in moderating the flow of nitrogen (N) to marine ecosystems. However, the magnitude of this N removal can vary dramatically both within and between estuaries due to the benthic habitats present. Here, we compare denitrification, coupled nitrification–denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) across a mosaic of benthic habitats in the subtropical Noosa River Estua...
Laboratory mesocosm incubations were undertaken to investigate the influence of burrowing shrimp Trypaea australiensis (marine yabby) on sediment reworking, physical and chemical sediment characteristics and nutrients in sandy sediments receiving mangrove (Avicennia marina) leaf litter. Mesocosms of sieved, natural T. australiensis inhabited sands, were continually flushed with fresh seawater and pre-incubated for 17 days prio...
Symbiodinium mitigate the combined effects of hypoxia and acidification on a noncalcifying cnidarianNARA Subscribed
Anthropogenic nutrient inputs enhance microbial respiration within many coastal ecosystems, driving concurrent hypoxia and acidification. During photosynthesis, Symbiodinium spp., the microalgal endosymbionts of cnidarians and other marine phyla, produce O 2 and assimilate CO 2 and thus potentially mitigate the exposure of the host to these stresses. However, such a role for Symbiodinium remains untested for noncalcifying cnid...
Summary Modern microbial mats are highly complex and dynamic ecosystems. Diffusive equilibration in thin films ( DET ) and diffusive gradients in thin films ( DGT ) samplers were deployed in a modern smooth microbial mat from Shark Bay in order to observe, for the first time, two‐dimensional distributions of porewater solutes during day and night time. Two‐dimensional sulfide and alkalinity distributions revealed a strong spat...
Top‐down and bottom‐up influences of jellyfish on primary productivity and planktonic assemblagesNARA Subscribed
A manipulative mesocosm experiment was done in a saline coastal lake in Australia to compare the top‐down and bottom‐up influences of jellyfish on primary production and planktonic assemblages. We hypothesized that non‐zooxanthellate jellyfish ( Catostylus mosaicus ) would exert both ‘top‐down’ (grazing) and ‘bottom‐up’ (nutrient excretion) effects, whereas zooxanthellate jellyfish ( Phyllorhiza punctata ) would only exert top...
Sulphate reduction rates (SRR) and nitrogen fixation rates (NFR) associated with isolated roots, rhizomes and sediment from the rhizosphere of the marine macrophytes Zostera noltii and Spartina maritima , and the presence and distribution of Bacteria on the roots and rhizomes, were investigated. Between 1‰ and 3‰ of the surface area of the roots and rhizomes of both macrophytes were colonized by Bacteria. Bacteria on the surfa...