The crater lake of Ilamatepec (Santa Ana) volcano, El Salvador: insights into lake gas composition and implications for monitoring

We here present the first chemical characterization of the volcanic gas plume issuing from the Santa Ana crater lake, a hyper-acidic crater lake (pH of − 0.2 to 2.5) in north-western El Salvador. Our results, obtained during regular surveys in 2017 and 2018 using a Multi-GAS instrument, demonstrate a hydrous gas composition (H2O/SO2 ratios from 32 to 205) and SO2 as the main sulfur species (H2S/SO2 = 0.03–0.1). We also find that gas composition evolved during our investigated period, with the CO2/SO2 ratio decreasing by one order of magnitude from March 2017 (37.2 ± 9.7) to November 2018 (< 3). This compositional evolution toward more magmatic (SO2-rich) compositions is interpreted in the context of the long-term evolution of the volcano following its 2005 and 2007 eruptions. We find that, in spite of reduced (background-level) seismicity, the magmatic gas supply into the lake was one order of magnitude higher in March 2017 (total volatile flux: 20,200–30,200 t/day) than in the following periods (total volatile flux: 900–10,167 t/day). We propose that the elevated magmatic/hydrothermal transport in March 2017, combined with a 15% reduction in precipitation, caused the volume of the lake to decrease, ultimately reducing its sulfur absorbing and scrubbing capacity, and hence causing the gas plume CO2/SO2 ratio to decrease. The recently observed increases in temperature, acidity, and salinity of the lake are consistent with this hypothesis. We conclude that the installation of a continuous, fully-automated Multi-GAS is highly desirable to monitor any future change in lake plume chemistry, and hence the level of degassing activity

Tracking Formation of a Lava Lake From Ground and Space: Masaya Volcano (Nicaragua), 2014–2017

A vigorously degassing lava lake appeared inside the Santiago pit crater of Masaya volcano (Nicaragua) in December 2015, after years of degassing with no (or minor) incandescence. Here we present an unprecedented-long (3 years) and continuous volcanic gas record that instrumentally characterizes the (re)activation of the lava lake. Our results show that, before appearance of the lake, the volcanic gas plume composition became unusually CO2 rich, as testified by high CO2/SO2 ratios (mean: 12.2 ± 6.3) and low H2O/CO2 ratios (mean: 2.3 ± 1.3). The volcanic CO2 flux also peaked in November 2015 (mean: 81.3 ± 40.6 kg/s; maximum: 247 kg/s). Using results of magma degassing models and budgets, we interpret this elevated CO2 degassing as sourced by degassing of a volatile-rich fast-overturning (3.6–5.2 m3&nbsp;s−1) magma, supplying CO2-rich gas bubbles from minimum equivalent depths of 0.36–1.4 km. We propose this elevated gas bubble supply destabilized the shallow (&lt;1 km) Masaya magma reservoir, leading to upward migration of vesicular (buoyant) resident magma, and ultimately to (re)formation of the lava lake. At onset of lava lake activity on 11 December 2015 (constrained by satellite-based MODIS thermal observations), the gas emissions transitioned to more SO2-rich composition, and the SO2 flux increased by a factor ∼40% (11.4 ± 5.2 kg/s) relative to background degassing (8.0 kg/s), confirming faster than normal (4.4 versus ∼3 m3&nbsp;s−1) shallow magma convection. Based on thermal energy records, we estimate that only ∼0.8 of the 4.4 m3&nbsp;s−1 of magma actually reached the surface to manifest into a convecting lava lake, suggesting inefficient transport of magma in the near-surface plumbing system

Practical and clinical utility of non-invasive vagus nerve stimulation (nVNS) for the acute treatment of migraine. A post hoc analysis of the randomized, sham-controlled, double-blind PRESTO trial

Background: The PRESTO study of non-invasive vagus nerve stimulation (nVNS; gammaCore®) featured key primary and secondary end points recommended by the International Headache Society to provide Class I evidence that for patients with an episodic migraine, nVNS significantly increases the probability of having mild pain or being pain-free 2 h post stimulation. Here, we examined additional data from PRESTO to provide further insights into the practical utility of nVNS by evaluating its ability to consistently deliver clinically meaningful improvements in pain intensity while reducing the need for rescue medication. Methods: Patients recorded pain intensity for treated migraine attacks on a 4-point scale. Data were examined to compare nVNS and sham with regard to the percentage of patients who benefited by at least 1 point in pain intensity. We also assessed the percentage of attacks that required rescue medication and pain-free rates stratified by pain intensity at treatment initiation. Results: A significantly higher percentage of patients who used acute nVNS treatment (n = 120) vs sham (n = 123) reported a ≥ 1-point decrease in pain intensity at 30 min (nVNS, 32.2%; sham, 18.5%; P = 0.020), 60 min (nVNS, 38.8%; sham, 24.0%; P = 0.017), and 120 min (nVNS, 46.8%; sham, 26.2%; P = 0.002) after the first attack. Similar significant results were seen when assessing the benefit in all attacks. The proportion of patients who did not require rescue medication was significantly higher with nVNS than with sham for the first attack (nVNS, 59.3%; sham, 41.9%; P = 0.013) and all attacks (nVNS, 52.3%; sham, 37.3%; P = 0.008). When initial pain intensity was mild, the percentage of patients with no pain after treatment was significantly higher with nVNS than with sham at 60 min (all attacks: nVNS, 37.0%; sham, 21.2%; P = 0.025) and 120 min (first attack: nVNS, 50.0%; sham, 25.0%; P = 0.018; all attacks: nVNS, 46.7%; sham, 30.1%; P = 0.037). Conclusions: This post hoc analysis demonstrated that acute nVNS treatment quickly and consistently reduced pain intensity while decreasing rescue medication use. These clinical benefits provide guidance in the optimal use of nVNS in everyday practice, which can potentially reduce use of acute pharmacologic medications and their associated adverse events. Trial registration: ClinicalTrials.gov identifier: NCT02686034

Predicting effect of changes in ‘fishable’ areas on fish and fisheries

This report aims to investigate the available tools for predicting the impact of various spatial management options on fisheries distribution, yield, profitability, and selectivity. Such spatial plans may affect the remaining ‘fishable’ areas by displacing and concentrating the fishing pressure, and so may alter stock abundances, distributions, size- and species catch composition and fuel expenditure and cost. The report provides early insights into how spatial plans that exclude certain fishing activities may affect these outcomes. Spatially explicit approaches are used, along with scenarios of underlying stock productivities and distributions, to assess the performance of spatial management measures. Scenario-based testing is conducted to examine the interrelated effects of management options and stock productivity. A major aspect of the work involved gathering and organizing information on specific zones from several sources such as Natura2000, CDDA, SPA, SAC, and UK-defined areas. We found that most of these zones did not have any previous management plans in place that would outline fishing restrictions. Therefore, we developed a method of assigning limitations to certain fishing techniques based on the perceived vulnerability of specific areas to these practices. This approach has allowed for an examination of how these restrictions potentially affect fish and fisheries.Initially, we used a static approach in anticipating the potential fishing effort displacement to measure the impact of fishing in the Northeast Atlantic area. Our research shows that while such spatial management measures may reduce fishing opportunities, it may be possible to offset in the short term some of these spatial opportunity losses by fishing in nearby locations (Figure 1). On the Med side, an analysis of fishing effort displacement from restricted areas in the Adriatic Sea is exemplified in a before/after situation, showing that the effort is not reduced but redistributed and can further redistribute far from the restricted areas.If in the short term, spatial management may increase operating costs by displacing the effort, this may eventually be recovered in the long term if the stock is recovering from previous overfishing. To determine whether conservation measures (such as Marine Protected Areas) that limit specific fishing techniques and areas could help mitigate the negative effects of fishing, a more advanced approach to fisheries management is required. This involves using a dynamic approach deploying spatial bioeconomic models that consider changes in environmental drivers and spatial restrictions, allowing it to assess potential changes in fishing effort facing, for example, new regulatory or ecological conditions. While bioeconomic models require more data and assumptions to forecast "alternative futures", they offer a more comprehensive approach to fisheries management, which is particularly useful as testing MPAs effects in real life is a challenge. A suite of bioeconomic models has been deployed to provide preliminary findings about the effect of spatial restrictions on fish, fisheries, benthos and bycatch:•International fisheries active in the North Sea were modeled using DISPLACE, testing the implementation of spatial restrictions to specific fishing techniques. Based on the simulations, the benthos status improved in areas where bottom fishing was excluded from previously fished areas and decreased in newly fished areas. However, the gain by EU closure areas was limited and no change in fish size selectivity detected as these areas are not really significant for bottom fishing and have not been initially designated to modify selectivity.•In the eastern Ionian Sea, different spatial restrictions for fishing techniques were evaluated using the DISPLACE model. While there may have been advantages to the fishing restrictions, there has been an increase in both unwanted catch and fishing effort, and no significant improvements were observed in the harvesting of adult fish. The alternative scenarios tested were insufficient to make fishing fleets more selective. Additionally, certain fishing fleets were economically adversely affected.•East Adriatic trawlers may benefit from being forced closer to shore after the closure of their traditional fishing grounds while the Italian trawling fleet experiences higher steaming costs, likely due to the closure of nursery grounds and FRAs and redistribution to other areas. ECOSPACE predicted that the mean trophic level of fish caught in deeper waters, closed to bottom trawlers but still accessible to pelagic fisheries, will increase. ECOSPACE indicated a marked rise in biodiversity in the central Adriatic area under the closures scenario. The reported outcome for ECOSPACE should be considered preliminary as it may have been influenced by the assumptions used to build and parameterize the model.•ECOSPACE predicted a significant rise in biomass for the southern North Sea in response to area closures. Fish biomass could increase by up to 15%. However, this increase may not be sufficient to compensate for the decline in biomass outside the MPA from more pressure on specific fish species. This, in turn, caused a decrease in overall catches. Within the MPAs, all fishing fleets experienced losses of up to 50%, while outside the MPAs, there was an increase of up to 13% in catches. Nonetheless, the gains outside the MPAs did not compensate for the losses incurred due to the closures.•ECOSPACE investigation on how spatial fisheries management affects the food web and fisheries in the eastern Ionian Sea was used to evaluate the spatial distribution of fishing effort for two scenarios - one with existing closed areas and another with possible future closed areas. Preliminary findings indicate that if all fishing activities are restricted from MPAs (as in the second scenario), there is an increase in fishing effort throughout the study area, rather than just around the MPAs.•Using an agent-based model of the southern North Sea and the German fisheries, spatial restrictions were shown to possibly result in reduction in fishing effort, concentration of fishing effort in the remaining open areas, longer steaming times, and lower profits. The spatial scenarios heavily affect the German shrimp fishery due to large overlaps with coastal shrimp fishing grounds, while flatfish and Nephrops fisheries are less affected. Scenarios reduced the fishing effort of all métiers suggesting that switching métiers and relocating fishing effort could not negate the impact of spatial fishing closures.•In the North Sea, the OSMOSE model was used to test scenarios of effort redistribution and effort reduction. The results indicated a slight increase in the biomass of demersal species, but a significant decrease in the biomass of pelagic species. Both scenarios showed an increase in the relative biomass of protected, endangered, and threatened (PET) species when effort was reduced. Additionally, changes in the food web led to an increase in the catch of commercial species above minimum conservation size.•A spatial BEMTOOL is being implemented applied to the Adriatic and western Ionian Seas active and passive demersal gears fleet segments. The effort data for the main ports in the study area was explored to identify the fishing grounds that are more frequently visited by fishers and to gain insights into their fishing strategies.In summary, prohibition of certain fishing techniques in all currently designated MPAs has minimal impact on the fisheries economy of most fleet-segments examined and fish populations in the short term. This is primarily because these areas are preserved due to their significance as hotspots of EU marine biodiversity, rather than selected for a high abundance of commercial fish. Some segments, however, may require &gt;15% extra effort to break even. In an upcoming study, SEAwise partners will investigate conservation areas the selectivity of fish size

Tracking Formation of a Lava Lake From Ground and Space: Masaya Volcano (Nicaragua), 2014–2017

A vigorously degassing lava lake appeared inside the Santiago pit crater of Masaya volcano (Nicaragua) in December 2015, after years of degassing with no (or minor) incandescence. Here we present an unprecedented-long (3 years) and continuous volcanic gas record that instrumentally characterizes the (re)activation of the lava lake. Our results show that, before appearance of the lake, the volcanic gas plume composition became unusually CO 2 rich, as testified by high CO 2 /SO 2 ratios (mean: 12.2 ± 6.3) and low H 2 O/CO 2 ratios (mean: 2.3 ± 1.3). The volcanic CO 2 flux also peaked in November 2015 (mean: 81.3 ± 40.6 kg/s; maximum: 247 kg/s). Using results of magma degassing models and budgets, we interpret this elevated CO 2 degassing as sourced by degassing of a volatile-rich fast-overturning (3.6–5.2 m 3 &nbsp;s −1 ) magma, supplying CO 2 -rich gas bubbles from minimum equivalent depths of 0.36–1.4 km. We propose this elevated gas bubble supply destabilized the shallow (&lt;1 km) Masaya magma reservoir, leading to upward migration of vesicular (buoyant) resident magma, and ultimately to (re)formation of the lava lake. At onset of lava lake activity on 11 December 2015 (constrained by satellite-based MODIS thermal observations), the gas emissions transitioned to more SO 2 -rich composition, and the SO 2 flux increased by a factor ∼40% (11.4 ± 5.2 kg/s) relative to background degassing (8.0 kg/s), confirming faster than normal (4.4 versus ∼3 m 3 &nbsp;s −1 ) shallow magma convection. Based on thermal energy records, we estimate that only ∼0.8 of the 4.4 m 3 &nbsp;s −1 of magma actually reached the surface to manifest into a convecting lava lake, suggesting inefficient transport of magma in the near-surface plumbing system