Major Disturbances Research Articles

Mapping the susceptibility of reefs to rubble accumulation across the Great Barrier Reef

Disturbance-induced rubble accumulations are described as “killing fields” on coral reefs as coral recruits suffer high post-settlement mortality, creating a bottleneck for reef recovery. The increasing frequency of coral bleaching events, that can generate rubble once coral dies, has heightened concerns that rubble beds will become more widespread and persistent. But we currently lack the tools to predict where rubble is most likely to accumulate. Here, we developed a modelling framework to identify areas that are likely to accumulate rubble on forereef slopes across the Great Barrier Reef. The algorithm uses new high-resolution bathymetric and geomorphic datasets from satellite remote sensing. We found that 47 km of reef slope (3% of the entire reef surveyed), primarily in the southern region, could potentially reach 50% rubble cover. Despite being statistically significant (p < 0.001), the effects of depth and aspect on rubble cover were minimal, with a 0.2% difference in rubble cover between deeper and shallower regions, as well as a maximum difference of 0.8% among slopes facing various directions. Therefore, we conclude that the effects of depth and aspect were insufficient to influence ecological processes such as larval recruitment and recovery in different coral communities. Maps of potential rubble accumulation can be used to prioritise surveys and potential restoration, particularly after major disturbances have occurred.

Movement ecology of an endangered mesopredator in a mining landscape

BackgroundEfficient movement and energy expenditure are vital for animal survival. Human disturbance can alter animal movement due to changes in resource availability and threats. Some animals can exploit anthropogenic disturbances for more efficient movement, while others face restricted or inefficient movement due to fragmentation of high-resource habitats, and risks associated with disturbed habitats. Mining, a major anthropogenic disturbance, removes natural habitats, introduces new landscape features, and alters resource distribution in the landscape. This study investigates the effect of mining on the movement of an endangered mesopredator, the northern quoll (Dasyurus hallucatus). Using GPS collars and accelerometers, we investigate their habitat selection and energy expenditure in an active mining landscape, to determine the effects of this disturbance on northern quolls.MethodsWe fit northern quolls with GPS collars and accelerometers during breeding and non-breeding season at an active mine site in the Pilbara region of Western Australia. We investigated broad-scale movement by calculating the movement ranges of quolls using utilisation distributions at the 95% isopleth, and compared habitat types and environmental characteristics within observed movement ranges to the available landscape. We investigated fine-scale movement by quolls with integrated step selection functions, assessing the relative selection strength for each habitat covariate. Finally, we used piecewise structural equation modelling to analyse the influence of each habitat covariate on northern quoll energy expenditure.ResultsAt the broad scale, northern quolls predominantly used rugged, rocky habitats, and used mining habitats in proportion to their availability. However, at the fine scale, habitat use varied between breeding and non-breeding seasons. During the breeding season, quolls notably avoided mining habitats, whereas in the non-breeding season, they frequented mining habitats equally to rocky and riparian habitats, albeit at a higher energetic cost.ConclusionMining impacts northern quolls by fragmenting favoured rocky habitats, increasing energy expenditure, and potentially impacting breeding dispersal. While mining habitats might offer limited resource opportunities in the non-breeding season, conservation efforts during active mining, including the creation of movement corridors and progressive habitat restoration would likely be useful. However, prioritising the preservation of natural rocky and riparian habitats in mining landscapes is vital for northern quoll conservation.

Feedback loops drive ecological succession: towards a unified conceptual framework.

The core principle shared by most theories and models of succession is that, following a major disturbance, plant-environment feedback dynamics drive a directional change in the plant community. The most commonly studied feedback loops are those in which the regrowth of the plant community causes changes to the abiotic (e.g. soil nutrients) or biotic (e.g. dispersers) environment, which differentially affect species availability or performance. This, in turn, leads to shifts in the species composition of the plant community. However, there are many other PE feedback loops that potentially drive succession, each of which can be considered a model of succession. While plant-environment feedback loops in principle generate predictable successional trajectories, succession is generally observed to be highly variable. Factors contributing to this variability are the stochastic processes involved in feedback dynamics, such as individual mortality and seed dispersal, and extrinsic causes of succession, which are not affected by changes in the plant community but do affect species performance or availability. Both can lead to variation in the identity of dominant species within communities. This, in turn, leads to further contingencies if these species differ in their effect on their environment (priority effects). Predictability and variability are thus intrinsically linked features of ecological succession. We present a new conceptual framework of ecological succession that integrates the propositions discussed above. This framework defines seven general causes: landscape context, disturbance and land-use, biotic factors, abiotic factors, species availability, species performance, and the plant community. When involved in a feedback loop, these general causes drive succession and when not, they are extrinsic causes that create variability in successional trajectories and dynamics. The proposed framework provides a guide for linking these general causes into causal pathways that represent specific models of succession. Our framework represents a systematic approach to identifying the main feedback processes and causes of variation at different successional stages. It can be used for systematic comparisons among study sites and along environmental gradients, to conceptualise studies, and to guide the formulation of research questions and design of field studies. Mapping an extensive field study onto our conceptual framework revealed that the pathways representing the study's empirical outcomes and conceptual model had important differences, underlining the need to move beyond the conceptual models that currently dominate in specific fields and to find ways to examine the importance of and interactions among alternative causal pathways of succession. To further this aim, we argue for integrating long-term studies across environmental and anthropogenic gradients, combined with controlled experiments and dynamic modelling.

Scientific approaches toward improving cervical cancer elimination strategies.

At the 2023 EUROGIN workshop scientific basis for strategies to accelerate the elimination of cervical cancer and its causative agent, human papillomavirus (HPV) were reviewed. Although some countries have reached key performance indicators toward elimination (>90% of girls HPV vaccinated and >70% of women HPV screened), most are yet to reach these targets, implying a need for improved strategies. Gender-neutral vaccination, even with moderate vaccination coverage was highlighted as a strategy to achieve elimination more rapidly. It is more resilient against major disturbances in vaccination delivery, such as what happened during the coronavirus pandemic. Further, an analysis of ethical/legal issues indicated that female-restricted vaccination is problematic. Extended catch-up of vaccination with concomitant screening, and outreach to vulnerable groups were highlighted. Although birth cohorts with high coverage of HPV vaccination at school are protected against HPV, and HPVs have a very low reproductive rate in women above age 35, adult women below age 30 have inadequate direct protection. In addition to herd protection from gender-neutral vaccination, this group can be protected by offering concomitant catch-up HPV vaccination and HPV screening. Furthermore, hepatitis B vaccination experiences indicate that elimination cannot be achieved without prioritizing vulnerable/migrant populations. The long-lasting durability of vaccination-induced antibody responses suggests prolonged protection with HPV vaccines when adequately administrated. Finally, cost-effectiveness modelling suggests that high-coverage HPV vaccination in multiple population segments will be resource-saving due to reduced need for screening. In summary, the workshop found that strategically optimal deployment of vaccination will accelerate elimination of HPV and cervical cancer.

Investigating the potential of aggregated mobility indices for inferring public transport ridership changes.

Aggregated mobility indices (AMIs) derived from information and communications technologies have recently emerged as a new data source for transport planners, with particular value during periods of major disturbances or when other sources of mobility data are scarce. Particularly, indices estimated on the aggregate user concentration in public transport (PT) hubs based on GPS of smartphones, or the number of PT navigation queries in smartphone applications have been used as proxies for the temporal changes in PT aggregate demand levels. Despite the popularity of these indices, it remains largely untested whether they can provide a reasonable characterisation of actual PT ridership changes. This study aims to address this research gap by investigating the reliability of using AMIs for inferring PT ridership changes by offering the first rigorous benchmarking between them and ridership data derived from smart card validations and tickets. For the comparison, we use monthly and daily ridership data from 12 cities worldwide and two AMIs shared globally by Google and Apple during periods of major change in 2020-22. We also explore the complementary role of AMIs on traditional ridership data. The comparative analysis revealed that the index based on human mobility (Google) exhibited a notable alignment with the trends reported by ridership data and performed better than the one based on PT queries (Apple). Our results differ from previous studies by showing that AMIs performed considerably better for similar periods. This finding highlights the huge relevance of dealing with methodological differences in datasets before comparing. Moreover, we demonstrated that AMIs can also complement data from smart card records when ticketing is missing or of doubtful quality. The outcomes of this study are particularly relevant for cities of developing countries, which usually have limited data to analyse their PT ridership, and AMIs may offer an attractive alternative.

Inhibition of Snake Venom Serine Proteases Activities by Specific Antibody

According to the World Health Organization, snake envenomation is a major neglected public health problem. In addition to deaths, these accidents cause other severe disabilities, such as amputations. Annually, around 2 million people worldwide are affected by snakebite, with Africa, Asia, and Latin America being the regions most affected. Snakes of the Bothrops genus are the main cause of snakebite accidents in Latin America. Serine proteases (SVSPs) are one of the main protein families that have been implicated in the alterations of the human hemostasis, which causes a tendency to increase thrombotic and hemorrhagic processes. Part of SVSPs, are thrombin-like enzymes (TLEs), which recognize and cleave human fibrinogen, but usually only releasing fibrinopeptide A or B and do not act on the coagulation Factor XIII. Consequently, these toxins contribute to coagulopathy by fibrinogen consumption, one of the major systemic hemostatic disturbances, frequently observed in snakebite victims. The bothropic antivenom is effective in reversing most of the systemic effects of envenomation when administered early in an adequate therapeutic dose. However, studies have demonstrated that, in some cases, antivenoms do not completely neutralize the action of SVSPs, which are co-responsible for systemic and local effects, such as coagulopathy and hemorrhage. In this context, a better understanding of SVSPs’ role in coagulopathy caused by envenomation, and developing new strategies to inhibit these toxins are important. To achieve this, we aimed in the current work to isolate an enriched pool of SVSPs from Bothrops jararaca and Bothrops atrox, to better understand the SVSPs’ interaction with murine monoclonal antibody (mAb) anti-SVSPs.

Ab. No. 59 Reliability of Dual Weighing Scale Biofeedback System (DWSBS), a New Apparatus for Assessment and Training of Weight Bearing Asymmetry (WBA)

Introduction: Weight bearing asymmetry leads to major impact on gait execution strategies post neurological conditions. A cheap and cost-effective apparatus which can be incorporated in routine use with less costs per session, will help treat asymmetry and enhance a near normal gait pattern with reduction in compensatory strategies. Introduction of new, cost effective and reliable apparatus against costly and cumbersome apparatus which is portable and needs less clinical expertise to use. Secondary objective is to target, population with neurological issues where weight bearing asymmetry leads to major gait disturbances. Methods: 56 Normal Healthy individuals (45-65 years) Instrumentation of DWSBS, by using 2 platforms for standing, measuring 12 x 12 inches each, embedded on a single platform, placed at a distance of 2 centimetres between them. A common display with digital output for both weighing scale was used. Reliability testing - 56 healthy individuals without any balance issues recruited and asked to stand bipedally, with eyes open on each of 2 weighing scales separately;post 3 trials, average of reading were documented. Data collected by 2 raters (Rater 1- reading on day 1 and 3; Rater 2 - reading on day 2) were analyzed using Cronbach’s alfa test in SPSS version 23 software. Result: Excellent reliability for Intrarater and interrater testing as per ICC values 0.9. neck ROM. Conclusion: The new apparatus has proven to be reliable and is fit to be tested for validity. Implications: DWSBS will help reduce to cost and execution-based burden for weight bearing asymmetry training.

Lower Ionospheric variations during the intense tectonic activity in the broader area of Greece on October of 2020

In this paper, we investigate the Lower ionospheric variations from TEC observations during the intense seismic activity of October 2020 in the area of Greece. The data were analysed using both, statistical analysis of TEC variations in order to detect uneven gross variations and Discrete Fourier analysis in order to investigate the TEC turbulence. The results of this investigation indicate that the High-Frequency limit fo of the ionospheric turbulence content, increases as aproaching the occurrence time of the earthquake, pointing to the earthquake epicenter, in accordance with our previous investigations. We conclude that the Lithosphere Atmosphere Ionosphere Coupling, LAIC, mechanism through acoustic or gravity waves could explain this phenomenology. In addition, the statistical analysis shows an excess greater than 3𝜎 from the mean TEC values, one and seven days before the earthquake. Since no major disturbance of the geomagnetic field occured during these days, we conclude that we probably observed precursory ionospheric variations in accordance to analogous findings from the variation of VH/VHF electromagnetic wave propagrations over strong earthquake areas.

Long COVID-19 Symptoms in People with Dementia or Mild Cognitive Impairment.

What is the impact of long COVID-19 on people with mild cognitive impairment (MCI) or dementia? Self-reported questionnaire was used for the report of long COVID-19 symptoms. People with MCI or dementia or their caregivers regarding patients' health were recruited COVID-19 throughout from the Athens Alzheimer's Association. We included 72 participants. Thirty had the diagnosis of MCI and 39 had dementia. Most symptoms lasted for 3-4 weeks. The majority of patients reported having all the symptoms, with fatigue being the major disturbance. The diagnosis and the management of long COVID-19 symptoms requires a more holistic and comprehensive approach.

Hypometabolism to survive the long polar night and subsequent successful return to light in the diatom Fragilariopsis cylindrus.

Diatoms, the main eukaryotic phytoplankton of the polar marine regions, are essential for the maintenance of food chains specific to Arctic and Antarctic ecosystems, and are experiencing major disturbances under current climate change. As such, it is fundamental to understand the physiological mechanisms and associated molecular basis of their endurance during the long polar night. Here, using the polar diatom Fragilariopsis cylindrus, we report an integrative analysis combining transcriptomic, microscopic and biochemical approaches to shed light on the strategies used to survive the polar night. We reveal that in prolonged darkness, diatom cells enter a state of quiescence with reduced metabolic and transcriptional activity, during which no cell division occurs. We propose that minimal energy is provided by respiration and degradation of protein, carbohydrate and lipid stores and that homeostasis is maintained by autophagy in prolonged darkness. We also report internal structural changes that manifest the morphological acclimation of cells to darkness, including the appearance of a large vacuole. Our results further show that immediately following a return to light, diatom cells are able to use photoprotective mechanisms and rapidly resume photosynthesis, demonstrating the remarkable robustness of polar diatoms to prolonged darkness at low temperature.

Long COVID‐19 symptoms in people with Dementia or Mild Cognitive Impairment

AbstractBackgroundLong COVID is broadly defined as signs, symptoms, and conditions that continue or develop after initial COVID‐19 or SARS‐CoV‐2 infection. What is its impact though on people with Mild Cognitive Impairment (MCI) or dementia?MethodSelf‐reported questionnaire was used for the report of the Long‐Covid 19 symptoms, regarding the duration, the exact symptoms, and the amount of the effect. People with MCI or dementia or their caregivers regarding patients’ health were recruited from the Athens Alzheimer’s Association.ResultOur sample consisted of 56 participants. Twenty‐two (39.3%) had the diagnosis of MCI, while 34 were people with dementia. Most of the people reported symptoms of Long Covid‐19 for 3‐4 weeks. Significant were all the symptoms reported (problem in breathing, fatigue, sore throat, and psychological distress/ depression), with the majority of the people answered the questionnaire reporting fatigue as the major disturbance. This was followed by the “Psychological distress/ depression”. The symptoms affected people significantly, with almost 40% reporting “Quite enough” disturbance.ConclusionLong Covid‐19 is reported to be similar to other geriatric syndromes, in that the exact mechanism that leads to the symptoms is complex and not clearly understood. Therefore, the diagnosis and the management of the Long Covid‐19 symptom requires a more holistic and comprehensive approach.

Asxl1-mutant Dominant Clones Have an Erythropoietic Lineage Deficiency through a Disturbed Epigenetic Landscape

Two hematologic features of red blood cells (RBCs) rank among the top three high risk factors associated with increased risk of malignant progression from clonal hematopoiesis (CH). These risk factors are macrocytosis as measured by elevated mean corpuscular volume (MCV) of 100 fL or greater and red cell distribution width (RDW) of 15% or greater. It is not known how these changes in RBC parameters are related to the leukemic transformation. Without major disturbance in the quantitative output of RBCs, these changes may reflect clone specific changes in erythropoiesis that are averaged in such measurements. We used an in vivo model of CH in zebrafish to study epigenetic and transcriptional changes in mutant clones, focusing on the erythropoietic program. In this model, mosaic somatic mutations in exon 12 of asxl1 with CRISPR-Cas9 mutagenesis are combined with color labeling of hematopoietic stem and progenitor cell (HSPC) clones. These mosaic asxl1 mutants exhibit an expansion of single-colored mutant clones to greater than 30% of hematopoietic output. No significant hematopoietic disturbance has been noted in these mutants by flow cytometric and morphologic analysis. To study clone specific effects of this epigenetic factor mutation, we sorted HSPCs from the dominant asxl1-mutant clone and compared it to HSPCs from control animals using transposase-accessible chromatin with sequencing (ATAC-seq) assay. Among over 22,000 peaks, we identified 998 (4.5%) that increased and 938 (4.2%) that decreased by 2-fold in asxl1-mutant clones compared to controls. Of the upregulated peaks, 73% were distal elements (+/- 100kb from transcriptional start sites, TSS) and 27% were proximal or promoter peaks (-2kb to +500bp from TSS), while in decreased peaks 67% were in distal elements and 33% in the proximal/promoter region. Pathway analysis of assigned genes related to decreased peaks identified a striking loss of the erythropoietic program and the heme biosynthesis process. HOMER analysis of sequences within the decreased peaks showed significant association with GATA ( q-value &amp;lt;0.001) and TRPS1 ( q-value &amp;lt;0.001) motifs. This was confirmed by individual assessment of gene loci for lineage-specifying transcriptional factors, such as tal1 and gata1a and genes in erythropoiesis, including alas2, cahz, tmod4 and the hemoglobin locus with known enhancers in nprl3 gene . Using an independently generated mutant zebrafish cohort, we performed bulk RNA-sequencing on sorted dominant clone and control HSPCs. Downregulated genes were consistent with a loss of erythroid differentiation program, with up to 16-fold downregulation of hbba1, hbaa1, alas2 and cahz although less pronounced or no significant changes were noted in erythroid transcription factors ( tal1, gata1a, lmo2) . Our data show that asxl1-mutant clones have an erythropoietic lineage defect with reduced epigenetic accessibility at lineage-specific loci with selective changes in gene expression. This ineffective erythropoiesis characterized by large MCV in mutant RBCs would increase the RDW due to the mixed contribution from mutant and wildtype clones in the peripheral blood. Our findings offer a biologic basis of the strong clinical association of abnormal RBC characteristics with higher risk CH for malignant transformation.

Ecological responses of epigaeic beetle composition to a volcanic eruption across temperate mountains featuring a forest‐steppe transition

Abstract Monitoring changes in species composition near active volcanoes is important to identify environmental factors that maintain biological diversity after major disturbances. We investigated the taxonomic composition of epigaeic beetles' assemblages in five mountains in north‐western Patagonia (Argentina) in the aftermath of the 2011 Puyehue Cordón‐Caulle Volcanic Complex eruption. The associations of beetle composition with the thermal environment, vegetation structure and soil characteristics were analysed using 10 m × 10 m plots with nine pitfall traps each, established 100 m apart in altitude on each mountain in 2005, 2006 (pre‐eruption) and 2012, 2015 and 2016 (post‐eruption). We found significant differences in beetle composition between forests and high‐Andean steppes before and after the eruption. The beetle composition of forests and high‐Andean steppes differed due to higher plant cover and lower pH and herb richness in forests. Six months after the eruption, the herbs almost disappeared and forests showed high ash accumulation and lower temperature than the high‐Andean steppes. In the medium term, plant cover, temperature and soil conditions—but not ash accumulation—remained as important correlates of beetle composition. Before the eruption, forest assemblages showed higher beetle diversity and Leiodidae indicator species, but Curculionidae predominated post‐eruption. Tenebrionidae and Carabidae were high Andean steppes indicators. Post‐eruption, the beetle composition in high‐Andean steppes did not change significantly except for an increase in Tenebrionidae indicator species. We concluded that the conservation of landscape diversity and environmental gradients maintaining the differentiation between ecoregions is essential to protect epigaeic beetle composition and for species survival after volcanic disturbances.

Responses of birds to observers holding popguns: Hunting history influences escape behavior of urban birds.

Human activities affect bird behavior both directly and indirectly. Birds constantly regulate their behavior in response to human disturbance. Gun hunting, a major directional disturbance, puts enormous selection pressure on birds. In China, gun bans have been in place for nearly 30 years, and little hunting using guns occurs in modern cities. However, little attention has been paid to whether a history of hunting still affects the behavioral adaptations of urban birds. In this study, we compared the flight initiation distance (FID) of the Eurasian tree sparrow Passer montanus, Azure-winged magpie Cyanopica cyanus, Common hoopoe Upupa epops and Eurasian magpie Pica pica in the presence of observers with or without popguns. The Eurasian tree sparrow, Azure-winged magpie, and Eurasian magpie effectively recognized the difference between the observers, and perceived the armed observer as a greater threat, exhibiting earlier escape behavior, but this phenomenon was not found in the Common hoopoe. The different expressions in FID of experimental bird species in China cities may be affected by the different levels of recognition of hunting pressure due to different hunting histories.

AusLAMP shines a light on space weather hazards in the Australian high-voltage power grid

A geomagnetic storm, also known as a geomagnetic disturbance (GMD), is a major disturbance of the Earth’s magnetic field caused by solar activity. A geomagnetic storm induces electric currents in the Earth that feed into power lines through substation neutral earthing, causing instabilities and even blackouts in electricity transmission systems. The intensity of geomagnetically induced currents (GICs) is closely associated with the electrical conductivity of the surrounding geology. In this paper, we analyse one of the most well-known geomagnetic storms, the 1989 “Québec storm” and 688 magnetotelluric (MT) survey sites from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) to gain insight into the space weather hazard posed for Australia's modern-day power grids. Transmission lines may exhibit local maxima at differing times depending on their spatial orientation and length with respect to the time-varying magnetic field. Localised peak voltages over 100 V can be observed on some individual lines. This assessment identifies the distribution of GICs in south-eastern Australia for the 1989 Québec storm and transmission lines that are more vulnerable to GICs. It is relevant to national strategies and risk assessment procedures to mitigate space weather hazards in the Australian high-voltage power grid and the design of a more resilient power transmission system. We also analyse the 2015 “St Patrick’s Day storm” to study under-estimation of the space weather hazard associated with the band-limited geomagnetic data and MT data sets. Key points The subsurface geology has a great influence on the intensity of geomagnetically induced electric fields, potentially causing up to three orders of magnitude difference between conductive basins and resistive cratonic regions in south-eastern Australia. Analysis using the 1989 “Québec geomagnetic storm” and AusLAMP magnetotelluric data shows the intensity of the geoelectric fields in south-eastern Australia could reach up to 5 [V/km]. Geomagnetically induced voltages in the Australian high-voltage power grid could be in excess of 100 V in some transmission lines for a geomagnetic storm with intensity comparable with the 1989 Québec geomagnetic storm.

Resistance of freshwater sediment bacterial communities to salinity disturbance and the implication for industrial salt discharge and climate change-based salinization

The impact of salinization on freshwater ecosystems became apparent during the 2022 ecological disaster in the Oder River, located in Poland and Germany, which was caused by salt discharge from mining activities. How bacterial communities respond to salinization caused by industrial salt discharge, or climate change-driven events, depends on the sensitivity of these complex bacterial communities. To investigate the sensitivity of bacterial communities to pulse salinization, we performed an experiment in the salinity range from 0.2 to 6.0. In addition, we sampled similar salinities in the littoral zone of the Baltic Sea where the bacterial communities are permanently exposed to the aforementioned salinities. To simulate a major disturbance, we included an ampicillin/streptomycin treatment in the experiment. Although the addition of antibiotics and increase in salinity had a significant impact on the water bacterial richness and community composition, only antibiotics affected the sediment bacterial community in the experiment. In contrast, sediment bacterial communities from the Baltic Sea littoral zone clustered according to salinity. Hence, sediment bacterial communities are more resistant to pulse changes in salinity than water bacteria but are able to adapt to a permanent change without loss in species richness. Our results indicate that moderate pulse salinization events such as industrial salt discharge or heavy storms will cause changes in the water bacterial communities with unknown consequences for ecosystem functioning. Sediment bacterial communities, however, will probably be unaffected in their ecosystem functions depending on the disturbance strength. Long-term disturbances, such as sea level rise or constant salt discharge, will cause permanent changes in the sediment bacterial community composition.

Ionospheric response over the Middle Asian region to the May 1967 geomagnetic storm

Ionospheric effects over the five Middle Asian ionospheric stations to the major space weather event of the May 25–26, 1967 geomagnetic storm with the Dst-index of −387 nT are studied based on ionosonde measurements that were not previously considered: Alma-Ata (43.25N, 76.92E), Karaganda (49.82N, 73.08E), Novokazalinsk (45.76N, 62.12E), Tashkent (41.33N, 69.62E), Ashkhabad (37.90N, 58.30E). The study presents a description of the geomagnetic storm effects on the ionosphere electron concentration from F-region down to the lower ionosphere, points out the storm effects in different ionospheric layers for the time period 22–31 May 1967. The observations indicate a major (≥50%) and long lasting (>28 h) negative ionospheric disturbance appeared during night- and daytime simultaneously at all five stations. The daytime foF2 values on 26 May were practically at the nighttime foF2 level on this day and well below the background daytime foF2 level. A rapid increase in h’F associated with reductions in foF2 occurred over all stations during the development of the main phase of the magnetic storm. Large changes in the critical frequencies foE, foEs, and fmin that is possible linked to the enhanced X-ray flux, increased intensity in solar cosmic rays, and precipitation of energetic neutral atoms at the respective latitudes were observed during 23–26 May 1967.

Loss and replacement of macroalgal standing stock and productivity after a major environmental disturbance

AbstractHabitat‐forming macroalgae are widely recognized as one of the most productive ecosystems on earth. However, relatively little is known about the variation in productivity over large spatiotemporal scales and the relative importance of environmental and biotic factors in influencing the quantity of carbon fixed. Here we leverage a large tectonic event to understand how fluctuations in the biomass of habitat‐forming macroalgae and changes in light availability influence primary productivity along 130 km of coastline over 5 years. We also quantify the effects of changes to species composition on primary productivity. This study revealed significant implications of a compromised light environment for the biomass of macroalgae and productivity rates. Immediately post‐earthquake, there was a substantial loss of biomass (an average of −83%) of a previously dominant large brown alga, Durvillaea spp., and very limited recovery of biomass over the next 5 years. Reductions in biomass coupled with changes in light attenuation resulted in average net primary production (NPP) from Durvillaea decreasing from 1130 g C m−2 year−1 before the earthquake to 192 g C m−2 year−1 after 5 years. Partial compensation of reduced NPP was facilitated by increases in the biomass of a smaller fucoid Carpophyllum maschalocarpum, but its productivity was considerably less on average, resulting in a reduction in carbon fixation. Overall, reductions in biomass resulted in a 2‐fold to 10‐fold drop in carbon fixation by canopy‐forming macroalgae over at least 5 years, while a degradation of the light environment further compromised primary productivity, and most likely detrital subsidies of organic matter to the nearshore ecosystem.

Logging, linear features, and human infrastructure shape the spatial dynamics of wolf predation on an ungulate neonate.

Humans are increasingly recognized as important players in predator-prey dynamics by modifying landscapes. This trend has been well-documented for large mammal communities in North American boreal forests: logging creates early seral forests that benefit ungulates such as white-tailed deer (Odocoileus virginianus), while the combination of infrastructure development and resource extraction practices generate linear features that allow predators such as wolves (Canis lupus) to travel and forage more efficiently throughout the landscape. Disturbances from recreational activities and residential development are other major sources of human activity in boreal ecosystems that may further alter wolf-ungulate dynamics. Here, we evaluate the influence that several major types of anthropogenic landscape modifications (timber harvest, linear features, and residential infrastructure) have on where and how wolves hunt ungulate neonates in a southern boreal forest ecosystem in Minnesota, USA. We demonstrate that each major anthropogenic disturbance significantly influences wolf predation of white-tailed deer fawns (n = 427 kill sites). In contrast with the "human shield hypothesis" that posits prey use human-modified areas as refuge, wolves killed fawns closer to residential buildings than expected based on spatial availability. Fawns were also killed within recently-logged areas more than expected. Concealment cover was higher at kill sites than random sites, suggesting wolves use senses other than vision, probably olfaction, to detect hidden fawns. Wolves showed strong selection for hunting along linear features, and kill sites were also closer to linear features than expected. We hypothesize that linear features facilitated wolf predation on fawns by allowing wolves to travel efficiently among high-quality prey patches (recently logged areas, near buildings), and also increase encounter rates with olfactory cues that allow them to detect hidden fawns. These findings provide novel insight into the strategies predators use to hunt ungulate neonates and the many ways human activity alters wolf-ungulate neonate predator-prey dynamics, which have remained elusive due to the challenges of locating sites where predators kill small prey. Our research has important management and conservation implications for wolf-ungulate systems subjected to anthropogenic pressures, particularly as the range of overlap between wolves and deer expands and appears to be altering food web dynamics in boreal ecosystems.

Core taxa drive microeukaryotic community stability of a deep subtropical reservoir after complete mixing.

Microeukaryotes are key for predicting the change of ecosystem processes in the face of a disturbance. However, their vertical responses to multiple interconnected factors caused by water mixing remain unknown. Here, we conducted a 12-month high-frequency study to compare the impacts of mixing disturbances on microeukaryotic community structure and stability over different depths in a stratified reservoir. We demonstrate that core and satellite microeukaryotic compositions and interactions in surface waters were not resistant to water mixing, but significantly recovered. This was because the water temperature rebounded to the pre-mixing level. Core microeukaryotes maintained community stability in surface waters with high recovery capacity after water mixing. In contrast, the changes in water temperature, chlorophyll-a, and nutrients resulted in steep and prolonged variations in the bottom core and satellite microeukaryotic compositions and interactions. Under low environmental fluctuation, the recovery of microbial communities did not affect nutrient cycling in surface waters. Under high environmental fluctuation, core and satellite microeukaryotic compositions in bottom waters were significantly correlated with the multi-nutrient cycling index. Our findings shed light on different mechanisms of plankton community resilience in reservoir ecosystems to a major disturbance over depths, highlighting the role of bottom microeukaryotes in nutrient cycling.