Lichen response to ammonia deposition defines the footprint of a penguin rookery

Ammonia volatilized from penguin rookeries is a major nitrogen source in Antarctic coastal terrestrial ecosystems. However, the spatial extent of ammonia dispersion from rookeries and its impacts have not been quantified previously. We measured ammonia concentration in air and lichen ecophysiological response variables proximate to an Adèlie penguin rookery at Cape Hallett, northern Victoria Land. Ammonia emitted from the rookery was 15N-enriched (δ15N value +6.9) and concentrations in air ranged from 36–75 µg m−3 at the rookery centre to 0.05 µg m−3 at a distance of 15.3 km. δ15N values and rates of phosphomonoesterase (PME) activity in the lichens Usnea sphacelata and Umbilicaria decussata were strongly negatively related to distance from the rookery and PME activity was positively related to thallus N:P mass ratio. In contrast, the lichen Xanthomendoza borealis, which is largely restricted to within an area 0.5 km from the rookery perimeter, had high N, P and 15N concentrations but low PME activity suggesting that nutrient scavenging capacity is suppressed in highly eutrophicated sites. An ammonia dispersion model indicates that ammonia concentrations sufficient to significantly elevate PME activity and δ15N values (≥0.1 µg NH3 m−3) occurred over c. 40–300 km2 surrounding the rookery suggesting that penguin rookeries potentially can generate large spatial impact zones. In a general linear model NH3 concentration and lichen species identity were found to account for 72 % of variation in the putative proportion of lichen thallus N originating from penguin derived NH3. The results provide evidence of large scale impact of N transfer from a marine to an N-limited terrestrial ecosystem

Seabird Modulations of Isotopic Nitrogen on Islands

The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystems’ structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents) and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in δ15N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers

Proteomic Analyses of Host and Pathogen Responses during Bovine Mastitis

The pursuit of biomarkers for use as clinical screening tools, measures for early detection, disease monitoring, and as a means for assessing therapeutic responses has steadily evolved in human and veterinary medicine over the past two decades. Concurrently, advances in mass spectrometry have markedly expanded proteomic capabilities for biomarker discovery. While initial mass spectrometric biomarker discovery endeavors focused primarily on the detection of modulated proteins in human tissues and fluids, recent efforts have shifted to include proteomic analyses of biological samples from food animal species. Mastitis continues to garner attention in veterinary research due mainly to affiliated financial losses and food safety concerns over antimicrobial use, but also because there are only a limited number of efficacious mastitis treatment options. Accordingly, comparative proteomic analyses of bovine milk have emerged in recent years. Efforts to prevent agricultural-related food-borne illness have likewise fueled an interest in the proteomic evaluation of several prominent strains of bacteria, including common mastitis pathogens. The interest in establishing biomarkers of the host and pathogen responses during bovine mastitis stems largely from the need to better characterize mechanisms of the disease, to identify reliable biomarkers for use as measures of early detection and drug efficacy, and to uncover potentially novel targets for the development of alternative therapeutics. The following review focuses primarily on comparative proteomic analyses conducted on healthy versus mastitic bovine milk. However, a comparison of the host defense proteome of human and bovine milk and the proteomic analysis of common veterinary pathogens are likewise introduced

Biomass and morphology of fine roots in temperate broad-leaved forests differing in tree species diversity: is there evidence of below-ground overyielding?

Biodiversity effects on ecosystem functioning in forests have only recently attracted increasing attention. The vast majority of studies in forests have focused on above-ground responses to differences in tree species diversity, while systematic analyses of the effects of biodiversity on root systems are virtually non-existent. By investigating the fine root systems in 12 temperate deciduous forest stands in Central Europe, we tested the hypotheses that (1) stand fine root biomass increases with tree diversity, and (2) ‘below-ground overyielding’ of species-rich stands in terms of fine root biomass is the consequence of spatial niche segregation of the roots of different species. The selected stands represent a gradient in tree species diversity on similar bedrock from almost pure beech forests to medium-diverse forests built by beech, ash, and lime, and highly-diverse stands dominated by beech, ash, lime, maple, and hornbeam. We investigated fine root biomass and necromass at 24 profiles per stand and analyzed species differences in fine root morphology by microscopic analysis. Fine root biomass ranged from 440 to 480 g m−2 in the species-poor to species-rich stands, with 63–77% being concentrated in the upper 20 cm of the soil. In contradiction to our two hypotheses, the differences in tree species diversity affected neither stand fine root biomass nor vertical root distribution patterns. Fine root morphology showed marked distinctions between species, but these root morphological differences did not lead to significant differences in fine root surface area or root tip number on a stand area basis. Moreover, differences in species composition of the stands did not alter fine root morphology of the species. We conclude that ‘below-ground overyielding’ in terms of fine root biomass does not occur in the species-rich stands, which is most likely caused by the absence of significant spatial segregation of the root systems of these late-successional species

Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)

Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ(15)N). Animal excrement is known to impact plant δ(15)N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint.This paper presents isotopic (δ(13)C and δ(15)N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of (15)N enrichment in fertilized plants is very large, with δ(15)N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ(15)N values ranged between -0.3 and 5.7‰. Intraplant and temporal variability in δ(15)N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ(13)C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk.The results presented in this study demonstrate the very large impact of seabird guano on maize δ(15)N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must be considered when interpreting isotopic data from archaeological material

Nitrogen stable isotopes indicate differences in nitrogen cycling between two contrasting Jamaican montane forests

Background and aims The aim of this study is to enhance our knowledge of nitrogen (N) cycling and N acquisition in tropical montane forests through analysis of stable N isotopes (δ15N). Methods Leaves from eight common tree species, leaf litter, soils from three depths and roots were sampled from two contrasting montane forest types in Jamaica (mull ridge and mor ridge) and were analysed for δ15N. Results All foliar δ15N values were negative and varied among the tree species but were significantly more negative in the mor ridge forest (by about 2 ‰). δ15N of soils and roots were also more negative in mor ridge forests by about 3 ‰. Foliar δ15N values were closer to that of soil ammonium than soil nitrate suggesting that trees in these forests may have a preference for ammonium; this may explain the high losses of nitrate from similar tropical montane forests. There was no correlation between the rankings of foliar δ15N in the two forest types suggesting a changing uptake ratio of different N forms between forest types. Conclusions These results indicate that N is found at low concentrations in this ecosystem and that there is a tighter N cycle in the mor ridge forest, confirmed by reduced nitrogen availability and lower rates of nitrification. Overall, soil or root δ15N values are more useful in assessing ecosystem N cycling patterns as different tree species showed differences in foliar δ15N between the two forest types

Five insights from the Global Burden of Disease Study 2019

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a rules-based synthesis of the available evidence on levels and trends in health outcomes, a diverse set of risk factors, and health system responses. GBD 2019 covered 204 countries and territories, as well as first administrative level disaggregations for 22 countries, from 1990 to 2019. Because GBD is highly standardised and comprehensive, spanning both fatal and non-fatal outcomes, and uses a mutually exclusive and collectively exhaustive list of hierarchical disease and injury causes, the study provides a powerful basis for detailed and broad insights on global health trends and emerging challenges. GBD 2019 incorporates data from 281 586 sources and provides more than 3.5 billion estimates of health outcome and health system measures of interest for global, national, and subnational policy dialogue. All GBD estimates are publicly available and adhere to the Guidelines on Accurate and Transparent Health Estimate Reporting. From this vast amount of information, five key insights that are important for health, social, and economic development strategies have been distilled. These insights are subject to the many limitations outlined in each of the component GBD capstone papers.Peer reviewe