Anthropogenic Change Research Articles

Subtle changes in plant diversity in the Bavarian Alps over the past eight decades.

Historical resurveys represent a unique opportunity to analyze vegetation dynamics over longer timescales than is typically achievable. Leveraging the oldest historical dataset of vegetation change in the Bavarian Alps, Germany, we address how environmental conditions, vegetation composition, and functional diversity in the calcareous grasslands of the Schachen region have changed across different elevational ranges over an 83-year timeframe. We document changes in regional average temperature and precipitation. We use indicator values (IV) for species' ecological preferences and their palatability to grazers to infer local conditions (temperature, soil moisture/fertility, and grazing regime). We further estimate changes in temporal beta-diversity and functional trait community composition between historical (1936) and contemporary (2019) surveys in two elevational (subalpine and alpine) belts. Both subalpine and alpine sites became drier; subalpine sites also became warmer with more palatable plants. Species occurrence and abundance in the Schachen region has not changed substantially over time despite changing macroclimate and local environmental conditions under anthropogenic change. Yet these grasslands have experienced several "invisible" changes in functional composition over the past 80 years. As the Schachen has become drier, species with traits related to drought tolerance and animal-based dispersal have increased in dominance. Specifically, in alpine sites, community-weighted means revealed that with low fecundity, higher potential for endo- and epizoochory (seed dispersal via animal gut and fur, respectively), higher foliar frost tolerance, and deeper dormancy increased in dominance. Similar trends were found for increasing dominance of low fecundity, epizoochorous species in subalpine sites. Vegetation data from resurveying historical plots in combination with changes in local conditions, classic biodiversity indices, and functional trait indices can provide more holistic insights into changes in the environment and potential impacts of those environmental changes on long-term plant community and functional diversity.

Assessing the Impact of Anthropogenic and Climate Change on Spider Diversity in Garhwal Himalaya

The state of Uttarakhand in India was created in the year 2000 with Dehradun as its capital, prompting increased human activity in the Doon Valley and dramatic shifts in land use patterns. Spiders are good indicator species for habitat quality and they can offer insights into disturbances in habitat either due to anthropogenic activities or climate change phenomenon. To assess the impact of anthropogenic activity in the Doon Valley, we conducted a long-term study, comparing it with Uttarkashi District. The study revealed 31 species and 28 genera of spiders across 13 families in the Doon Valley, while Uttarkashi District exhibited 37 species and 31 genera across 17 families, including the rare Asian Tarantulas (Haplocosmia himalayana, Pocock, 1899), a member of the Theraphosidae family. Pholcidae and Salticidae were consistently found in both regions, with Araneidae predominating. Changes in species distribution, influenced by anthropogenic activities and climate variations, indicate ongoing ecosystem shifts.

A consistent budgeting of terrestrial carbon fluxes

Accurate estimates of CO2 emissions from anthropogenic land-use change (ELUC) and of the natural terrestrial CO2 sink (SLAND) are crucial to precisely know how much CO2 can still be emitted to meet the goals of the Paris Agreement. In current carbon budgets, ELUC and SLAND stem from two model families that differ in how CO2 fluxes are attributed to environmental and land-use changes, making their estimates conceptually inconsistent. Here we provide consistent estimates of ELUC and SLAND by integrating environmental effects on land carbon into a spatially explicit bookkeeping model. We find that state-of-the-art process-based models overestimate SLAND by 23% (min: 8%, max: 33%) in 2012–2021, as they include hypothetical sinks that in reality are lost through historical ecosystem degradation. Additionally, ELUC increases by 14% (8%, 23%) in 2012–2021 when considering environmental effects. Altogether, we find a weaker net land sink, which makes reaching carbon neutrality even more ambitious. These results highlight that a consistent estimation of terrestrial carbon fluxes is essential to assess the progress of net-zero emission commitments and the remaining carbon budget.

Epigenetic responses of trees to environmental stress in the context of climate change.

In long-lived tree populations, when environmental change outpaces rates of evolutionary adaptation, plasticity in traits related to stress tolerance, dormancy, and dispersal may be vital for preventing extinction. While a population's genetic background partly determines its ability to adapt to a changing environment, so too do the many types of epigenetic modifications that occur within and among populations, which vary on timescales orders of magnitude faster than the emergence of new beneficial alleles. Consequently, phenotypic plasticity driven by epigenetic modification may be especially critical for sessile, long-lived organisms such as trees that must rely on this plasticity to keep pace with rapid anthropogenic environmental change. While studies have reported large effects of DNA methylation, histone modification, and non-coding RNAs on the expression of stress-tolerance genes and resulting phenotypic responses, little is known about the role of these effects in non-model plants and particularly in trees. Here, we review new findings in plant epigenetics with particular relevance to the ability of trees to adapt to or escape stressors associated with rapid climate change. Such findings include specific epigenetic influences over drought, heat, and salinity tolerance, as well as dormancy and dispersal traits. We also highlight promising findings concerning transgenerational inheritance of an epigenetic 'stress memory' in plants. As epigenetic information is becoming increasingly easy to obtain, we close by outlining ways in which ecologists can use epigenetic information better to inform population management and forecasting efforts. Understanding the molecular mechanisms behind phenotypic plasticity and stress memory in tree species offers a promising path towards a mechanistic understanding of trees' responses to climate change.

Approaches and methods to study wildlife cancer.

The last few years have seen a surge of interest from field ecologists and evolutionary biologists to study neoplasia and cancer in wildlife. This contributes to the One Health Approach, which investigates health issues at the intersection of people, wild and domestic animals, together with their changing environments. Nonetheless, the emerging field of wildlife cancer is currently constrained by methodological limitations in detecting cancer using non-invasive sampling. In addition, the suspected differential susceptibility and resistance of species to cancer often make the choice of a unique model species difficult for field biologists. Here, we provide an overview of the importance of pursuing the study of cancer in non-model organisms and we review the currently available methods to detect, measure and quantify cancer in the wild, as well as the methodological limitations to be overcome to develop novel approaches inspired by diagnostic techniques used in human medicine. The methodology we propose here will help understand and hopefully fight this major disease by generating general knowledge about cancer, variation in its rates, tumour-suppressor mechanisms across species as well as its link to life history and physiological characters. Moreover, this is expected to provide key information about cancer in wildlife, which is a top priority due to the accelerated anthropogenic change in the past decades that might favour cancer progression in wild populations.

Long- and short-term coupling of sea surface temperature and atmospheric CO2 during the late Paleocene and early Eocene

The late Paleocene and early Eocene (LPEE) are characterized by long-term (million years, Myr) global warming and by transient, abrupt (kiloyears, kyr) warming events, termed hyperthermals. Although both have been attributed to greenhouse (CO2) forcing, the longer-term trend in climate was likely influenced by additional forcing factors (i.e., tectonics) and the extent to which warming was driven by atmospheric CO2 remains unclear. Here, we use a suite of new and existing observations from planktic foraminifera collected at Pacific Ocean Drilling Program Sites 1209 and 1210 and inversion of a multiproxy Bayesian hierarchical model to quantify sea surface temperature (SST) and atmospheric CO2 over a 6-Myr interval. Our reconstructions span the initiation of long-term LPEE warming (~58 Ma), and the two largest Paleogene hyperthermals, the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) and Eocene Thermal Maximum 2 (ETM-2, ~54 Ma). Our results show strong coupling between CO2 and temperature over the long- (LPEE) and short-term (PETM and ETM-2) but differing Pacific climate sensitivities over the two timescales. Combined CO2 and carbon isotope trends imply the carbon source driving CO2 increase was likely methanogenic, organic, or mixed for the PETM and organic for ETM-2, whereas a source with higher δ13C values (e.g., volcanic degassing) is associated with the long-term LPEE. Reconstructed emissions for the PETM (5,800 Gt C) and ETM-2 (3,800 Gt C) are comparable in mass to future emission scenarios, reinforcing the value of these events as analogs of anthropogenic change.

An efficient and generalisable approach for mapping paddy rice fields based on their unique spectra during the transplanting period leveraging the CIE colour space

As one of the most important staple foods globally, rice sustains nearly half of the world's population. Accurate and timely paddy rice mapping is, thus, essential for rice-related policy-making to ensure food security in the context of anthropogenic, environmental and climate changes. However, paddy rice mapping remains a challenging task since it usually has similar spectral characteristics to other land covers. In this research, for the first time, an entirely new approach, called RiceTColour, was proposed for mapping rice fields within the Commission Internationale de l'Eclairage (CIE) colour space based on their unique spectra during the rice transplanting period as observed in remotely sensed imagery. We demonstrate that transplanted rice fields, representing a mixture of soil, water and rice seedlings, consistently exhibit relatively low spectral values in both SWIR and NIR bands across various geographical locations, leading to their unique dark green colours in the false-colour image composed of SWIR, NIR and Red bands. Based upon this, we transformed these three spectral bands into the CIE colour space where paddy rice was found to be readily and completely separated from the other land covers. Straightforward, but specific classification criteria were established within the CIE colour space to differentiate paddy rice from the other land covers. The proposed RiceTColour, thus, represents a new approach for paddy rice identification, that is mapping paddy rice using the CIE colour space based upon the previous underexplored remotely sensed spectra of paddy fields during the transplanting season. The effectiveness of the proposed method was investigated over five rice-planting regions distributed across different geographical regions, characterised by different climates, rice cropping intensities, irrigation schemes and cultural practices. Specifically, the mapping criteria established in a training site (S1) were directly generalised to the other four sites (S2 to S5) for paddy rice mapping. Experimental results demonstrated that the RiceTColour method consistently achieved the most accurate and balanced classifications across all five sites compared with four benchmark comparators: a SAR-based method, an index-based method and two supervised classifier-based methods. In particular, the RiceTColour method performed relatively stable, producing an overall accuracy exceeding 95% in the training site (S1) as well as the four generalised sites (S2 to S5), which is an encouraging result. Such efficient yet stable rice mapping results across various rice-planting regions suggest a very strong generalisation capability of the proposed RiceTColour method. In consideration of the relatively large planting area of paddy rice fields globally, the proposed parameter-free, efficient, and generalisable RiceTColour method, thus, holds great potential for widespread application in various rice-planting areas worldwide.

Characterization of biotic and abiotic signatures of modern lake sediments of western India, and its palaeo-environmental implications

A multi-proxy study of biotic and abiotic components was conducted on surface sediment samples from six lakes/wetlands located along the western transitional boundary of the contemporary Indian Summer Monsoon (ISM) in the Indian Subcontinent. The primary goal is to assess the suitability of various proxies as representatives of modern vegetation, environmental and climatic conditions. The collected data indicate significant variations in the composition and density of pollen in response to climate-induced and anthropogenic ecological changes throughout the northwest India transect. The palynological studies from eastern Rajasthan shows high forest elements in comparison to western Haryana and western Uttar Pradesh. In addition, the palynological data was juxtaposed with other biotic proxies such as diatom and isotopic studies, along with geochemical proxies and paleomagnetic data of the surface lake sediments. The presence of marker pollen taxa including Cerealia type Poaceae, Chenopodiaceae, and Brassicaceae, allows for distinct recognition of anthropogenic activities throughout the whole transect. The diversity and distribution of diatoms also support the palynological data in response to climate-induced and anthropogenic ecological changes. Furthermore, grain size, geochemistry (TOC/TN ratio with stable carbon isotope), and magnetic susceptibility data offer crucial insights about the sediment's depositional settings and general mineralogical composition. Stable carbon isotope data shows C3 dominance in relatively humid areas and C4 dominance in semi-arid areas, suggesting climate-driven control over sediment organic matter composition. Canonical correspondence analysis (CCA) indicates that biotic variables (pollen, diatom, stable isotopic composition) are significantly controlled by modern precipitation and temperature. Redundancy analysis reveals a significant influence of current average temperature and precipitation on major element oxide variations in surface lake sediments. Therefore, we propose using palynological, stable carbon isotope, diatom data, along with grain size, environmental magnetism, and geochemistry, to establish a multiproxy modern analogue for quantitative palaeoclimatic reconstructions. As a result, this study provides the first modern analogues from a climate-sensitive region that separates the area under ISM influence from an area with meager precipitation in western India.

Using joint species distribution modelling to identify climatic and non‐climatic drivers of Afrotropical ungulate distributions

The relative importance of the different processes that determine the distribution of species and the assembly of communities is a key question in ecology. The distribution of any individual species is affected by a wide range of environmental variables as well as through interactions with other species; the resulting distributions determine the pool of species available to form local communities at fine spatial scales. A challenge in community ecology is that these interactions (e.g. competition, facilitation, etc.) often are not directly measurable. Here, we used hierarchical modelling of species communities (HMSC), a recently developed framework for joint species distribution modelling, to estimate the role of biotic effects alongside environmental factors using latent variables. We investigate the role of these factors determining species distributions in communities of Artiodactyla, Perissodactyla and Proboscidea in the Afrotropics, an area of peak species richness for hoofed mammals. We also calculate pairwise trait dissimilarity between these species, from a mixture of morphological and behavioural traits, and investigate the relationship between dissimilarity and estimated residual co‐occurrence in the model. We find that while ungulate distributions appear to be predominantly determined (~ 70%) by climatic variables, such as precipitation, a substantial proportion of the variance in ungulate species distributions (~ 30%) can also be attributed to modelled latent variables that likely represent a combination of dispersal barriers and biotic factors. Although we find only a weak relationship between residual co‐occurrence and trait dissimilarity, we suggest that our results may show evidence that biotic factors, likely influenced by historical barriers to species dispersal, are important in determining species communities over a continental area. The HMSC framework can be used to provide insight into factors affecting community assembly at broad scales, and to make more powerful predictions about future species distributions as we enter an era of increasing impacts from anthropogenic change.

Ecogeomorphological Investigation of Anthropogenic Changes in the Kızılırmak River Mouth, Türkiye

Ecogeomorphological Investigation of Anthropogenic Changes in the Kızılırmak River Mouth, Türkiye

Transformation of Ecosystems of Floodplain Water Bodies under Current Natural and Anthropogenic Changes and Possible Strategies for their Conservation

Transformation of Ecosystems of Floodplain Water Bodies under Current Natural and Anthropogenic Changes and Possible Strategies for their Conservation

Hyperspectral characterization of vegetation in hemiboreal, boreal and Arctic peatlands using a geographically extensive field dataset

Northern peatlands store up to 25% of global soil organic carbon and function as important hotspots for biodiversity. However, they are facing degradation from climate change driven by human activities as well as anthropogenic land use changes, up to the point of endangering the ecosystems' functioning and the storage of soil organic carbon entailed within them. The surface vegetation of northern peatlands is an important indicator of the ecosystem's functioning and ecohydrology, highlighting the importance of its large-scale, continuous monitoring. Approaches utilizing hyperspectral data for monitoring vegetation health and species composition can also be applied to peatland vegetation. To support the development of methods for interpreting hyperspectral satellite data from peatlands, we conducted a comprehensive in situ study of hemiboreal, boreal, sub-Arctic and Arctic peatland vegetation. We measured the reflectance spectra (350–2500 nm), soil moisture, and various vegetation-related attributes from a total of 446 vegetation plots in Estonia and Finland, from a 1500 km south-north interval. We then investigated (i) the spectral variation in surface vegetation of hemiboreal, boreal, sub-Arctic and Arctic peatlands and (ii) explored its connection to plant functional types (PFTs) and soil moisture, as well as evaluated the potential of hyperspectral data in estimating PFT cover using simple vegetation indices and partial least square (PLS) regression. Our results indicate that (i) the best spectral regions to retrieve information regarding the PFT vary greatly especially between vascular plants and bryophytes, (ii) the reflectance at an individual wavelength as well as simple vegetational index can, to some extent, predict the PFT, and that (iii) the PLS regression can predict the PFT with good accuracy. Overall, our findings demonstrate the potential of using hyperspectral data in monitoring PFTs in northern peatlands. The spectral library and the ancillary data from the peatland sites collected for this study are available as open data.

Increasing environmental variability inhibits evolutionary rescue in a long-lived vertebrate

Evolutionary rescue, whereby adaptive evolutionary change rescues populations from extinction, is theorized to enable imperiled animal populations to persist under increasing anthropogenic change. Despite a large body of evidence in theoretical and laboratory settings, the potential for evolutionary rescue to be a viable adaptation process for free-ranging animals remains unknown. Here, we leverage a 38-year dataset following the fates of 53,959 Magellanic penguins (Spheniscus magellanicus) to investigate whether a free-ranging vertebrate species can morphologically adapt to long-term environmental change sufficiently to promote population persistence. Despite strong selective pressures, we found that penguins did not adapt morphologically to long-term environmental changes, leading to projected population extirpation. Fluctuating selection benefited larger penguins in some environmental contexts, and smaller penguins in others, ultimately mitigating their ability to adapt under increasing environmental variability. Under future climate projections, we found that the species cannot be rescued by adaptation, suggesting similar constraints for other long-lived species. Such results reveal how fluctuating selection driven by environmental variability can inhibit adaptation under long-term environmental change. Our eco-evolutionary approach helps explain the lack of adaptation and evolutionary rescue in response to environmental change observed in many animal species.

Does polymixis complicate prediction of high‐frequency dissolved oxygen in lakes and reservoirs?

AbstractAs lake and reservoir ecosystems transition across major environmental regimes (e.g., mixing regime) resulting from anthropogenic change, setting predictive expectations is imperative. We tested the hypothesis that (dissolved) oxygen is more predictable in monomictic reservoirs that thermally stratify throughout the summer (warm) season compared to polymictic reservoirs that stratify intermittently. Using two‐hourly vertical profiles of oxygen, we compared daily‐aggregated errors of oxygen predictions from random forests across and within two monomictic and two polymictic reservoirs in the south‐central (subtropical) USA. Although one monomictic reservoir was typically more predictable than the polymictic reservoirs, the hypereutrophic, small monomictic reservoir had less predictable oxygen patterns potentially related to rapid oxygen cycling and intrusions of oxygenated waters in the hypolimnion without mixing. Daily mixing did not relate strongly to model errors. Water temperature, depth, and wind were the most important predictors, but were not clearly related to season or mixing. Lastly, we compared multiple model types (regression, neural network, and process‐based) in one polymictic reservoir to test how our interpretations of oxygen predictability were sensitive to model type, finding that the models generally agreed; however, the process‐based model poorly predicted oxygen in the middle of the vertical profiles (5 m) where most models performed poorly due to a temporally unstable, vacillating metalimnion. Our results suggest predicting reservoir oxygen dynamics may be easier in stratified reservoirs, but eutrophication and complex hydrodynamics may cause forecasting surprises especially for those who use or manage water resources in mono‐ or dimictic reservoirs.

Cost-efficient PCR based DNA barcoding of marine invertebrate specimens with NovaSeq amplicon sequencing.

The marine environment harbors high biodiversity; however, it is poorly understood. Nucleotide sequence data of all marine organisms should be accumulated before natural and/or anthropogenic environmental changes jeopardize the marine environment. In this study, we report a cost-effective and easy DNA barcoding method. This method can be readily adopted without using library preparation kits. It includes multiplex PCR of short targets, indexing PCR, and outsourcing to a sequencing service using the NovaSeq system. We targeted four mitochondrial genes [cytochrome c oxidase subunit I (COI), COIII, 16S rRNA (16S), and 12S rRNA (12S)] and three nuclear genes [18S rRNA (18S), 28S rRNA (28S), internal transcribed spacer 2 (ITS2)] in 95 marine invertebrate specimens, which were primarily annelids. The primers, including adapters and indices for NovaSeq sequencing, were newly designed. Two PCR runs were conducted. The 1st PCR amplified specific loci with universal primers and the 2nd added sequencing adapters and indices to the 1st PCR products. The gene sequences obtained from the FASTQ files were subjected to BLAST search and phylogenetic analyses. One run using 95 specimens yielded sequences averaging 2816bp per specimen for a total length of six loci. Nuclear genes were more successfully assembled compared with mitochondrial genes. A weak but significantly negative correlation was observed between the average length of each locus and success rate of the assembly. Some of the sequences were almost identical to the sequences obtained from specimens collected far from Japan, indicating the presence of potentially invasive species identified for the first time. We obtained gene sequences efficiently using next-generation sequencing rather than Sanger sequencing. Although this method requires further optimization to increase the success rate for some loci, it is used as a first step to select specimens for further analyses by determining the specific loci of the targets.

The Effects of Oxidative Stress on RNA Editing with Insight into the Relationship Between Air Pollution and Alzheimer's Disease

Human interactions with the environment today add pressure on the world’s resources and ecosystems, which in turn harm human health. Many anthropogenic environmental changes, including climate change, biodiversity loss, and pollution, have accelerated morbidity and mortality. Research across multiple countries have found correlations between anthropogenic air pollution exposure and neurological degeneration, particularly with Alzheimer’s disease (AD). RNA editing induced by oxidative stress is one possible mechanism in which air pollution increases the risk of AD. To study this further, RNA adenosine-to-inosine (A-to-I) alterations were analyzed to identify a mechanism linking air pollution to neurological degeneration. These alterations occur in RNA, most prevalently in the central nervous system (CNS). Adenosine deaminase acting on RNA (ADAR) enzymes mediate A-to-I alterations and are essential for mammalian development and survival. ADAR mediated alterations have been associated with AD and the A-to-I occurrence frequency may increase in polluted environments that trigger increased oxidative stress. To test this possibility, wildtype (WT) and ADAR knockout (adr-2(-) Caenorhabditis elegans in their first larval (L1) developmental stage were exposed to juglone solution for 0, 15, and 60 minute experimental settings. For the two worm strains, WT and adr-2(-), the 0 minute treatment was the control, the 15 minute treatment represented acute oxidative stress exposure, and the 60 minute treatment represented chronic exposure. RNA was extracted from both groups and quantitative Real Time PCR (qRT-PCR) was used to measure the expression of gst-4, an Alzheimer’s associated gene (sel-12), and adr-2 normalized to the expression of gpd-3, the housekeeping gene that corrected for systemic errors. The gst-4 gene expression confirmed that oxidative stress occurred. Lack of adr-2 gene significantly decreased sel-12 expression at acute exposure, but adr-2 gene expression in WT worms did not significantly change across treatments. It remains to be determined whether oxidative stress impacts RNA editing of target mRNAs. Future studies are needed to explore the role of adr-2 in promoting sel-12 expression.

Ancestral lineages of dietary exposure to an endocrine disrupting chemical drive distinct forms of transgenerational subfertility in an insect model

Across the globe, many species of insects are facing population decline. This is largely driven by anthropogenic changes to the environment, including the widespread exposure of invertebrates to endocrine disrupting chemicals (EDCs), which impair fertility. To test whether generations of Drosophila melanogaster born from parents exposed to a common dietary EDC, equol, could recover reproductive function, we quantified the reproductive capacity of the two subsequent generations. Using a novel suite of flow cytometry assays to assess sperm functionality in real time, we find that sperm function is compromised across three generations, even after non-exposed in individuals contribute to the breeding population. Though the sex ratio alters in response to EDC exposure, favouring the survival of female offspring, most lineages with ancestral EDC exposure exhibit persistent subfertility in both the male and female. Male offspring with ancestral EDC exposure present with reduced fertility and dysfunctional spermatozoa, whereby spermatozoa are metabolically stressed, lack DNA integrity and present with permanent epigenetic alterations. Across generations, male and female offspring demonstrate distinct patterns of reproductive characteristics, depending upon the specific lineage of EDC exposure. Our results illustrate how dietary EDCs present in agricultural plants could promote transgenerational subfertility and contribute to declining insect populations.

Historical Southern Hemisphere biomass burning variability inferred from ice core carbon monoxide records

Biomass burning plays an important role in climate-forcing and atmospheric chemistry. The drivers of fire activity over the past two centuries, however, are hotly debated and fueled by poor constraints on the magnitude and trends of preindustrial fire regimes. As a powerful tracer of biomass burning, reconstructions of paleoatmospheric carbon monoxide (CO) can provide valuable information on the evolution of fire activity across the preindustrial to industrial transition. Here too, however, significant disagreements between existing CO records currently allow for opposing fire histories. In this study, we reconstruct a continuous record of Antarctic ice core CO between 1821 and 1995 CE to overlap with direct atmospheric observations. Our record indicates that the Southern Hemisphere CO burden ([CO]) increased by 50% from a preindustrial mixing ratio of ca. 35 ppb to ca. 53 ppb by 1995 CE with more variability than allowed for by state-of-the-art chemistry-climate models, suggesting that historic CO dynamics have been not fully accounted for. Using a 6-troposphere box model, a 40 to 50% decrease in Southern Hemisphere biomass-burning emissions, coincident with unprecedented rates of early 20th century anthropogenic land-use change, is identified as a strong candidate for this mismatch.

Temporal dynamics in gastrointestinal helminth infections of sympatric mouse lemur species (Microcebus murinus and Microcebus ravelobensis) in Northwestern Madagascar

Madagascar's lemur populations are declining in dwindling habitats due to anthropogenic expansion and changing climatic conditions. Gastrointestinal parasites can be important indicators to assess the health status of threatened species. However, parasites, hosts and the environment are connected in complex interactions. The present study aimed to disentangle the impact of seasonal and several host-specific factors (sex, species, age, reproductive status, and body mass) on endoparasitism in two small-bodied, co-occurring lemur species (Microcebus murinus and Microcebus ravelobensis) in the Ankarafantsika National Park. Helminth prevalence and egg shedding intensity was investigated via copromicroscopic examination of 810 fecal samples that were obtained from 178 individuals across an 11-month period with a longitudinal approach via repeated captures in a 30.6 ha forest area. Both mouse lemur hosts shed seven morphologically distinct egg types (assigned to Subulura baeri, unidentified Enterobiinae, Spirura sp., Lemuricola sp., two Hymenolepididae spp., one unidentified ascarid). Postmortem examination of two deceased individuals enabled assignment of adult worms to egg morphotypes of S. baeri, Spirura sp. and one Hymenolepididae sp., supported by molecular analysis. A significant seasonal variation was observed in the occurrence of the three most common helminth species S. baeri (total prevalence 71%), unidentified Enterobiinae (46%) and Spirura sp. (38%), with a higher likelihood of infection with advancing dry season. Neither host species, sex nor reproductive status had a significant effect on gastrointestinal helminth infections. Host body mass showed pronounced seasonal changes but did not differ significantly between infected and non-infected individuals. The pathogenic effects of gastrointestinal helminths therefore likely remained within compensable limits in the studied mouse lemur populations. Our findings highlight the prominent influence of seasonal changes on helminth communities. The results of combined morphologic and genetic approaches can furthermore help to overcome limitations of parasite identification via copromicroscopy by linking egg morphology to DNA sequences.

Recent and projected changes in global climate may increase nicotine absorption and the risk of green tobacco sickness

BackgroundDermal transfer of nicotine during tobacco harvest can cause green tobacco sickness (GTS), characterized by nausea, vomiting, headache and dizziness. Rainfall and high temperatures are etiological factors known to increase the prevalence of GTS. We analyzed recent and projected trends in these factors for major tobacco-growing regions to assess potential exacerbation in GTS occurrence.MethodsWe analyzed climate parameters, including recent trends (since the 1970s) in temperature and precipitation metrics during the tobacco harvest period for Southern Brazil; Yunnan Province, China; Andhra State, India; and North Carolina, USA. We applied Shared Socio-economic Pathways (SSPs) based scenarios for Tier 1 Scenario Model Intercomparison Project (ScenarioMIP) within the Coupled Model Intercomparison Project phase 6 (CMIP6), (SSPs of 1–2.6, 3–7.0 and 5–8.5 from 2020 to 2100). Established protocol for nicotine dermal patches and temperature were used as a proxy to estimate potential nicotine absorption.ResultsFor three locations, cumulative maximum temperatures during harvest and temperature extremes rose significantly since the 1970s as did cumulative rainfall during harvest. Projected maximum temperatures at SSP 3–7.0 and 5–8.5 projections through 2100 did increase for all locations. Estimates of nicotine skin absorption with rising temperature show significant increases for both recent changes in three locations, and for all locations for SSP projections of 3–7.0 and 5–8.5 from 2020 to 2100.ConclusionsThis study across multiple continents, highlights a potential link between recent and projected anthropogenic change and potential increases in GTS risk. Under SSP 5–8.5, nicotine absorption could increase by ~50% by the end of the century, which may have widespread impacts on the incidence of GTS, especially among younger tobacco workers.