Mercury (Hg) concentrations and stable isotope signatures in golden eagle eggs 2009-2013: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Mercury (Hg) is a neurotoxin and there has been global concern over its impact on humans and wildlife. It has been predicted that global Hg emissions may rise in the future because of increased coal-fired power generation, but, in 2013, the United Nations Environment Programme (UNEP) agreed The Minamata Convention on Mercury, a global treaty to protect human health and the environment from the adverse effects of mercury. An overarching aim of the convention is to control the anthropogenic releases of Hg to the environment. Therefore, long-term trends in environmental Hg concentrations are uncertain. One cost-effective means of assessing such trends is to monitor exposure in sentinel wildlife species. Golden eagles Aquila chrysaetos breed and forage in the Scottish uplands and could prove a sentinel for changing Hg deposition in upland terrestrial areas and associated wildlife exposure. We measured Hg residues in failed golden eagle eggs with the aim of providing baseline data on current levels of exposure. Specifically, we measured Hg concentrations in failed eggs laid between 2009 and 2013 in inland (> 3km from the coast) and coastal (<3 km from the coast) nests. We distinguished nests in this way because coastal nesting birds can feed on seabirds that can accumulate high levels of Hg themselves. Marine dietary Hg inputs could potentially obscure any changes in Hg accumulation associated with altered upland terrestrial Hg deposition, and so we hypothesized that only eggs from inland nests may be useful sentinels. In conjunction with Hg measurements, we examined stable isotope (SI) signatures (carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S)) to determine if they differed between eggs from inland and coastal nests in a manner consistent with feeding primarily on terrestrial and marine prey, respectively. We also examined Hg concentrations and SI signatures of failed white-tailed sea eagle (Haliaeetus albicilla) eggs from nests on the west coast of Scotland. We used these measurements as a comparator against which to assess the extent to which SI and Hg measurements in eggs from coastal golden eagle nests might be indicative of feeding on marine prey and scavenge. We found that SI signatures (particularly δ34S isotopic ratios) and Hg concentrations were similar in golden eagle eggs from coastal nests and white tailed sea eagle eggs. SIs and Hg concentrations in eggs from inland nests were much more variable, and a third had SI signatures that were the same as those of eggs from coastal nests, suggesting that they too were laid by females feeding on a coastal diet. A cluster of seven eggs from inland nests had distinctive δ34S and δ15N values (below 11.0 ‰ and 5.7 ‰ respectively) and it was inferred that these were most likely laid by females feeding terrestrially. Hg concentrations were non-detectable in these seven eggs whereas the median concentration in golden eagle eggs associated with coastal feeding was 0.412 µg/g dry weight, similar to that (0.569 µg/g dry weight) in white tailed sea eagle eggs. Hg concentrations in all eggs were below those thought to be associated with embryotoxic effects. The lack of detectable Hg concentrations in GE eggs associated with upland terrestrial feeding is problematic if these eggs are to be used as sentinels of change in upland Hg concentrations. Re-analysis of a set of eggs using a more sensitive analytical technique may resolve this issue and should be explored, otherwise other sentinels may need to be investigated

Mercury (Hg) concentrations in predatory bird livers and eggs as an indicator of changing environmental concentrations: a Predatory Bird Monitoring Scheme (PBMS) report

Concern over the potential health effects of mercury (Hg) has prompted an international agreement, the Minamata Convention on Mercury, that aims to control anthropogenic releases to the environment and reduce potential impacts on humans and wildlife. Monitoring is required to determine to what extent the convention is successful. The PBMS has monitored long-term trends in environmental Hg concentration using raptors and fish-eating birds as sentinels to track changes in exposure. Overall, PBMS monitoring of Hg in predatory birds provides an evidence base by which the impact of the Minamata Convention on environmental mercury concentrations in Britain can be assessed. The current study consisted of four main aims that would help rationalize and inform our long-term Hg monitoring. (i) Updating long-term data for liver Hg concentrations in sparrowhawks, (Accipiter nisus), a sentinel for exposure in lowland terrestrial habitats. (ii) Exploration of the use of alternative tissues for monitoring Hg in sparrowhawks. (iii) Comparison of trends in liver Hg residues in sparrowhawks and kestrels (Falco tinnunculus) to examine if trends in sparrowhawks, which feed on relatively mobile avian prey, reflect those in kestrels which mainly feed on small mammals that are more likely to reflect local contamination. (iv) Completion of work initiated last year to explore the potential for using Hg concentrations in the eggs of inland-feeding golden eagles (Aquila chrysaetos) as a sentinel to track changes in Hg bioavailability and uptake by biota in upland terrestrial systems. We measured liver Hg residues in sparrowhawks that had died in 2013 and 2014 to quantify current Hg exposure in lowland terrestrial habitats and to add to previously reported long-term data. Mercury residues in birds that died in 2013 and 2014 were largely consistent with those reported in recent previous years and were below those associated with mortalities. Three birds had residues higher than those associated with potential adverse effects on reproduction. Analysis of long-term data (1990-2014) indicated liver Hg residues in sparrowhawks vary with age and sex; concentrations are highest in adult males. Starvation also elevates liver Hg concentrations. Taking age and sex into account and using only data for non-starved birds, we investigated temporal trends and found that, although there has been between-year variation in liver Hg concentrations, there has been no consistent upward or downward trend. We used the long-term dataset to define “current baseline” liver Hg concentrations against which levels in future years, and consistent time trends, can be quantitatively and rapidly assessed. We found that total Hg concentrations in sparrowhawk liver, kidney and brain were closely related. We conclude it is possible to transfer our long-term monitoring of Hg in sparrowhawks (including retrospective calculation of “current baseline concentrations”) to analysis of kidney or brain. This would preserve [what are relatively small] sparrowhawk livers for other analyses. Comparison of historic trends in liver Hg in sparrowhawks and kestrels indicated that rates of decline during 1980-1998 were similar in the two species. This is consistent with the premise that sparrrowhawks are as likely as kestrels to be representative of changes in environmental exposure to (and associated bioaccumulation of) Hg in lowland terrestrial systems. The conclusion of our work on Hg concentrations in golden eagle eggs enabled us to quantify a “baseline concentration” for eggs laid by females feeding predominantly on terrestrial prey. We can use this to identify significant changes in future exposure and associated bioaccumulation and thereby use our measurements as sentinel of future change in Hg bioavailability in upland habitats in northern Britain

Ecosystem CO2 and CH4 exchange in a mixed tundra and a fen within a hydrologically diverse Arctic landscape: 1. Modeling versus measurements

CO2 and CH4 exchange are strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for these effects in the model ecosys were tested by comparing modeled CO2 and CH4 exchange with CO2 fluxes measured by eddy covariance from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008, along a topographic gradient at Daring Lake, NWT. In an upland tundra, rises in net CO2 uptake in warmer years were constrained by declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5kPa and by rises in CO2 effluxes with greater active layer depth. Consequently, net CO2 uptake rose little with warming. In a lowland fen, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake were greater than those in the tundra. Greater declines in CO2 influxes with warming in the tundra were modeled from greater soil-plant-atmosphere water potential gradients that developed under higher D in drained upland soil, and smaller rises in CO2 effluxes with warming in the fen were modeled from O2 constraints to heterotrophic and belowground autotrophic respiration from a shallow water table in poorly drained lowland soil. CH4 exchange modeled during July and August indicated very small influxes in the tundra and larger effluxes characterized by afternoon emission events caused by degassing of warming soil in the fen. Emissions of CH4 modeled from degassing during soil freezing in October-November contributed about one third of the annual total

Indium-111-labeled polyclonal human immunoglobulin: identifying focal infection in patients positive for human immunodeficiency virus

Contains fulltext : 4753.pdf (publisher's version ) (Open Access

A randomised controlled trial to assess the antithrombotic effects of aspirin in type 1 diabetes : role of dosing and glycaemic control

Background The enhanced thrombotic milieu in diabetes contributes to increased risk of vascular events. Aspirin, a key antiplatelet agent, has inconsistent effects on outcomes in diabetes and the best dosing regimen remains unclear. This work investigated effects of aspirin dose and interaction with glycaemia on both the cellular and protein components of thrombosis. Methods A total of 48 participants with type 1 diabetes and 48 healthy controls were randomised to receive aspirin 75 or 300 mg once-daily (OD) in an open-label crossover study. Light transmittance aggregometry and fibrin clot studies were performed before and at the end of each treatment period. Results Aspirin demonstrated reduced inhibition of collagen-induced platelet aggregation (PA) in participants with diabetes compared with controls, although the higher dose showed better efficacy. Higher aspirin dose facilitated clot lysis in controls but not individuals with diabetes. Collagen-induced PA correlated with glycaemic control, those in the top HbA1c tertile having a lesser inhibitory effect of aspirin. Threshold analysis suggested HbA1c levels of > 65 mmol/mol and > 70 mmol/mol were associated with poor aspirin response to 75 and 300 mg daily doses, respectively. Higher HbA1c was also associated with longer fibrin clot lysis time. Conclusions Patients with diabetes respond differently to the antiplatelet and profibrinolytic effects of aspirin compared with controls. In particular, those with elevated HbA1c have reduced inhibition of PA with aspirin. Our findings indicate that reducing glucose levels improves the anti-thrombotic action of aspirin in diabetes, which may have future clinical implications. Trial registration EudraCT, 2008-007875-26, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2008-007875-26

Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

Genetic, abiotic and social influences on sex differentiation in cichlid fishes and the evolution of sequential hermaphroditism

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73799/1/j.1467-2979.2005.00184.x.pd