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Zircon megacrysts are locally abundant in 1–40 cm-thick orthopyroxenite veins within peridotite host rocks in the Archaean Lewisian gneiss complex from NW Scotland. The veins formed by metasomatic interaction between the ultramafic host and Si-rich melts are derived from partial melting of the adjacent granulite-facies orthogneisses. The interaction produced abundant orthopyroxene and, within the thicker veins, phlogopite, pargasite and feldspathic bearing assemblages. Two generations of zircon are present with up to 1 cm megacrystic zircon and a later smaller equant population located around the megacryst margins. Patterns of zoning, rare earth element abundance and oxygen isotopic compositions indicate that the megacrysts crystallized from crustal melts, whereas the equant zircon represents new neocryst growth and partial replacement of the megacryst zircon within the ultramafic host. Both zircon types have U–Pb ages of ca. 2464 Ma, broadly contemporaneous with granulite-facies events in the adjacent gneisses. Zircon megacrysts locally form > 10% of the assemblage and may be associated to zones of localized nucleation or physically concentrated during movement of the siliceous melts. Their unusual size is linked to the suppression of zircon nucleation and increased Zr solubility in the Si-undersaturated melts. The metasomatism between crustal melts and peridotite may represent an analog for processes in the mantle wedge above subducting slabs. As such, the crystallization of abundant zircon in ultramafic host rocks has implications for geochemistry of melts generated in the mantle and the widely reported depletion of high field strength elements in arc magmas.

The spatial distribution of greenschist-facies retrograde reaction products in metabasic gneisses from Iona, western Scotland, has been investigated. The retrograde products may be broadly accounted for by a single reaction, but their different spatial and temporal development indicates that a series of reactions occur with significantly different scales of metasomatic transfer. After initial fluid influx linked to deformation-induced high permeability, reaction-enhanced permeability, coupled to cycling of fluid pressure during faulting, strongly controls the pervasive retrogression. Ca-plagioclase and pyroxene in the gneisses are replaced by albite and chlorite in pseudomorphic textures, and this is followed by localized epidotization of the albite. Two main generations of epidote are formed in the gneisses. Epidosite formation is associated with prominent zones of cataclasite indicating a strong link between faulting and fluid influx. In contrast, complete alteration of albite to epidote in the host metabasic gneisses is spatially complex, and areas of pervasive alteration may be constrained by both epidote-rich veins and cataclasites. In other instances, reaction fronts are unrelated to structural features. Volume changes associated with individual stages of the reaction history strongly control the localized distribution of epidote and the earlier more widespread development of chlorite and albite. Such behaviour contrasts with adjacent granitic gneisses where epidotization is restricted to local structural conduits. Many small-scale mineralized fractures with evidence of having previously contained fluids do not enhance the pervasive retrogression of the metabasic gneisses and represent conduits of fluid removal. Retrogression of these basement gneisses is dominated by a complex combination of reaction-enhanced and reaction-restricted permeability, kinetic controls on the nucleation of reaction products, changes in fluid composition buffered by the reactions, and periodic local migration of fluids associated with fault movements. This combination generates spatially complex patterns of epidotization that are limited by cation supply rather than fluid availability and alternations between focused and pervasive types of retrogression.

Outgrowths of zircon and xenotime are abundant on detrital zircon in a greenschist facies regional metamorphic slate from the Scottish Highlands. Back-scattered electron images reveal that ca. 3-μm wide zircon outgrowths are porous, inclusion-rich and contain fine-grained intergrowths with xenotime. Focused ion beam milling, transmission electron microscopy and low-voltage scanning transmission electron microscopy show that the outgrowth microstructure is complex, composed of mis-orientated nano-crystalline zircon and a poorly crystalline zircon–xenotime complex. Well-defined micron-sized xenotime is also present within the outgrowth. Micro-textures show that the outgrowth developed in a polyphase history during cooling and exhumation. Accommodation space for the outgrowth is probably generated by a combination of thermal decompaction and the migration of defects in adjacent quartz driven by the force of crystallisation. Zircon may be unique in its ability to record textural evidence of events during uplift and exhumation that are not recorded in major silicate phases.

The response of garnet and zircon to prograde amphibolite-facies metamorphism in late Proterozoic mica schists from the Scottish Highlands has been investigated. Spatial analysis of zircon populations using scanning electron microscopy was undertaken in Dalradian Schists that have undergone a sequence of prograde garnet growth and localised breakdown reactions involving coupled dissolution–reprecipitation. Fluid availability and matrix permeability strongly control this metamorphic response and different generations of garnet contain radically different populations of metamorphic micro-zircon and associated changes in the detrital zircon population. Micro-zircon abundance increases during garnet growth, whereas that of detrital zircon decreases. The mineralogy of the matrix influences zircon abundance in porphyroblast phases, where garnet overgrows a micaceous matrix zircon-rich garnet forms and where it overgrows a quartzofeldspathic matrix the result is zircon-poor garnet. Following garnet growth, micro-zircon abundance decreases at each stage of the prograde reaction history, with sillimanite-zone schists containing the lowest abundance, suggesting micro-zircons are texturally less stable at staurolite- and sillimanite-grade metamorphism. Micro-zircons are distributed evenly across host minerals in the matrix, with the exception of retrograde chlorite where micro-zircons are absent due to fluids removing Zr before new zircon can precipitate. There is an overall decrease in the mode of zircon at each stage of the reaction history, indicating that zircon is a highly reactive phase during amphibolite-facies metamorphism and is very sensitive to individual prograde and retrograde reactions.

The thermal history of the Hebridean Igneous Province has been determined through the application of low-temperature thermochronology to the four central complexes in the province. The zircon (U-Th)/He age (59.4±3.3 Ma, 1σ, n=18) and the ages from each complex (60.7±2.3 Ma for Skye; 58.0±0.4 Ma for Mull; 55.9±3.2 Ma for Ardnamurchan; 55.6±2.7 Ma for Rum) are indistinguishable from the crystallization ages. Apatite fission-track ages (61.2-57.2 Ma, mean of 59.3±3.4 Ma) from the major plutonic units also overlap crystallization ages, implying that on a regional scale the Hebridean Igneous Province cooled rapidly to near-surface temperatures immediately after emplacement. However, apatite fission-track ages and track lengths and apatite (U-Th)/He ages from some small-volume intrusions in the Skye and Rum central complexes identify localized mid-Eocene (45-47 Ma) cooling. Forward and inverse modelling suggests a discrete heating-cooling event at c. 47 Ma, which may have been caused by structurally controlled localized advection of heat above shallow emplacement. This is the first suggestion of Eocene magmatism in the Hebridean Igneous Province.

Apatite fission-track analysis of rocks from the Sierra Nevada basement, southern Spain reveals a detailed record of Neogene denudation. This is combined with evidence of the accumulation of clastic sedimentary rocks in the adjacent Granada Basin to provide a comprehensive record of the denudation of the emerging mountain block. Fission-track ages of c. 9-10 and 4 Ma obtained from the basement reveal periods of rapid cooling linked to tectonic denudation of the metamorphic core. The first major pulse of erosion from the Sierra Nevada produced proximal conglomerates in the marine basin and is constrained at c. 7 Ma using Sr-isotope stratigraphy. No major signal of rapid cooling is preserved by the fission-track systems in the basement block associated with this event. Apatite fission-track data from the conglomerates show young ages and short track lengths indicative of reheating. Modelling of the data suggests that heating occurred at around 4 Ma and is linked to movement of hot fluids through the basin. The ability of thermochronometers to record erosional events during the early stages of orogenesis is critically examined and we suggest that in young rising mountain blocks surface processes are incapable of keeping pace with rock uplift, and denudation principally occurs via tectonic processes.

BackgroundObesity, a major global health problem, is associated with increased cardiometabolic morbidity and mortality. Protein glycosylation is a frequent posttranslational modification, highly responsive to inflammation and ageing. The prospect of biological age reduction, by changing glycosylation patterns through metabolic intervention, opens many possibilities. We have investigated whether weight loss interventions affect inflammation- and ageing-associated IgG glycosylation changes, in a longitudinal cohort of bariatric surgery patients. To support potential findings, BMI-related glycosylation changes were monitored in a longitudinal twins cohort.MethodsIgG N-glycans were chromatographically profiled in 37 obese patients, subjected to low-calorie diet, followed by bariatric surgery, across multiple timepoints. Similarly, plasma-derived IgG N-glycan traits were longitudinally monitored in 1680 participants from the TwinsUK cohort.ResultsLow-calorie diet induced a marked decrease in the levels of IgG N-glycans with bisecting GlcNAc, whose higher levels are usually associated with ageing and inflammatory conditions. Bariatric surgery resulted in extensive alterations of the IgG N-glycome that accompanied progressive weight loss during 1-year follow-up. We observed a significant increase in digalactosylated and sialylated glycans, and a substantial decrease in agalactosylated and core fucosylated IgG N-glycans (adjusted p value range 7.38 × 10−04–3.94 × 10−02). This IgG N-glycan profile is known to be associated with a younger biological age and reflects an enhanced anti-inflammatory IgG potential. Loss of BMI over a 20 year period in the TwinsUK cohort validated a weight loss-associated agalactosylation decrease (adjusted p value 1.79 × 10−02) and an increase in digalactosylation (adjusted p value 5.85 × 10−06).ConclusionsAltogether, these findings highlight that weight loss substantially affects IgG N-glycosylation, resulting in reduced glycan and biological age.HighlightsObesity is associated with inflammation-related agalactosylated and bisected IgG glycoforms.IgG bisected glycoforms decrease after low-calorie diet.IgG galactosylation and sialylation increase after bariatric surgery-induced weight loss.Progressive decrease of BMI is associated with increased IgG galactosylation, implying a reduction of biological age.

Aquaculture is an increasingly important food-producing sector, providing protein for human consumption. However, marine aquaculture often struggles for space due to the crowded nature of human activities in many marine coastal areas, and because of limited attention from spatial planning managers. Here, we assess the need for coastal spatial planning, emphasising the establishment of suitable areas for the development of marine aquaculture, termed Allocated Zones for Aquaculture (AZAs), in which aquaculture has secured use and priority over other activities, and where potential adverse environmental impacts and negative interactions with other users are minimised or avoided. We review existing examples of marine aquaculture spatial development worldwide and discuss the proper use of site selection in relation to different legal and regulatory requirements. National or regional authorities in charge of coastal zone management should carry out spatial planning defining optimal sites for aquaculture to promote development of sustainable marine aquaculture and avoid conflict with other users, following a participatory approach and adhering to the principles of ecosystem-based management.

If eradication has become infeasible, containment of an invasive species may be a practical alternative. Like all management actions, however, containment comes with costs, so it is important to quantify the potential benefits accruing from a proposed containment action. Here we examine the ongoing spread of the toxic, invasive cane toad ( Rhinella marina ) across northern Australia, and a proposal to contain their spread and prevent their arrival in Australia’s Pilbara bioregion (178,000 km 2 ), ca. 500 kms south of the toad’s 2024 invasion front. We then evaluate the likely biodiversity costs if toads spread to the Pilbara. Under a ‘do-nothing’ scenario, toads are predicted to arrive via natural dispersal in the Pilbara between 2035 and 2055. They are predicted to colonise almost the entirety of the Pilbara bioregion. We predict that 25 vertebrate taxa resident in the Pilbara are likely to show population declines driven by lethal poisoning. Of the 25 at-risk taxa, eight are endemic to the Pilbara. A further two taxa are not endemic to the region but toad colonisation of the Pilbara will result in > 90% of their range being occupied by toads. Hence, we predict that the spread of toads to the Pilbara will cause an additional five mammals and four reptile species to be added to the threatened species list, and cause another species to be upgraded in threat status. These likely losses will also have cultural impacts for the First Nations people of the Pilbara, and cause economic impacts for the Pilbara’s primary industry; mining. Overall, our results show that predicted losses of the no-action option are high, and likely justify an attempt to exclude toads through establishment of a containment zone.

Coastal aquaculture is a globally expanding enterprise. Currently, 1200 salmon farms operate in coastal Norway, yet their capacity to aggregate and subsequently modify wild fish distributions is poorly known. Aggregations of wild fish at 9 farms and 9 control locations were counted on 3 separate days in June to August 2007. On each sampling occasion, 6 counts were made at 5 distinct depth-strata at each farm and control location. Wild fish were 1 to 3 orders of magnitude more abundant at farms than at control sites, depending on the location. Gadoid fish (Pollachius virens,Gadus morhuaandMelanogrammus aeglefinus) dominated farm-associated assemblages and were present across a wide range of sizes, from juveniles to large adults. Estimated total farm-aggregated wild fish biomass averaged 10.2 metric tonnes (t) per farm across the 9 farms (range: 600 kg to 41.6 t). Applied across the geographical range of Norway’s 1200 salmon farms, our estimates indicate that salmon farms attract and aggregate over 12 000 t of wild fish into a total of just 750 ha of coastal waters on any given day in summer. Possible consequences of these persistent, substantial aggregations of wild fishes at farms include a heightened potential for the transfer of pathogens from salmon farms to wild fish and among adjacent salmon farms, and altered availability of wild fish to fisheries. Restrictions on fishing in the immediate surrounds of salmon farms may avoid farms acting as ecological traps, particularly for species with depressed populations such asG. morhua, which are highly attracted to farms.