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We live amid a global wave of anthropogenically driven biodiversity loss: species and population extirpations and, critically, declines in local species abundance. Particularly, human impacts on animal biodiversity are an under-recognized form of global environmental change. Among terrestrial vertebrates, 322 species have become extinct since 1500, and populations of the remaining species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45% mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown about this \"Anthropocene defaunation\"; these knowledge gaps hinder our capacity to predict and limit defaunation impacts. Clearly, however, defaunation is both a pervasive component of the planet's sixth mass extinction and also a major driver of global ecological change.

In Moldova, there has been a long-term decline in the population, mainly due to high levels of emigration. The article presents an analysis of population dynamics in Moldova over the last three decades, and estimates the contributions of fertility, mortality and migration to this process. Using population censuses, data on the population with usual residence, vital statistics and data on Moldovan immigrants from the host countries’ statistical institutes,we estimate population changes between 1991–2021, and present demographic projections up to 2040. The results show that migration outflows account for more than 90% of the depopulation trend, with high levels of premature mortality accelerating the natural decline. The fall in births is associated with a decrease in the reproductive-age population. The total fertility rate has been decreasing gradually, while the cohort fertility rates have not fallen below 1.75 live births per woman. Past migration and low fertility are projected to result in long-term population decline. Demographic ageing is expected to increase. While population decline cannot be stopped, its scale can be limited through reductions in emigration and mortality. This study on population decline in Moldova helps to complete the demographic picture of Europe in the 20th century and into the 21st century.

Japan has the world’s largest old population ratio; thus, aging is an urgent societal issue. As global trends seem to be following Japan’s social changes, there is an emphasis on municipalities becoming more age-friendly. Hence, we examine the age-friendliness of 135 Japanese municipalities, selecting 240 resident architectural designers and constructors to assess their municipalities using the Age-Friendly Cities and Communities Questionnaire (AFCCQ). The findings indicate that Japan lacks “outdoor spaces and buildings”. Additionally, the evaluation of “housing”, “community support and health services”, and “transportation” in populated municipalities in the past five years was found to be significantly higher than that in depopulated ones. Age-friendliness is significantly affected by the AFCCQ total score (hereafter, Score) based on “housing”, “social participation”, “community support and health services”, “transportation”, and “financial situation” evaluations. High specificity (0.939) was found when the score was treated as a marker of depopulation; an age-friendly approach is a necessary condition for preventing depopulation. Furthermore, a lack of “communication and information” was observed in municipalities with a higher rate of single-person households aged 65 years and older. Therefore, resident architectural designers’ and constructors’ assessments, combined with the AFCCQ, will be a powerful tool for evaluating the age-friendliness of municipalities.

The term \"herd immunity\" is widely used but carries a variety of meanings [1-7]. Some authors use it to describe the proportion immune among individuals in a population. Others use it with reference to a particular threshold proportion of immune individuals that should lead to a decline in incidence of infection. Still others use it to refer to a pattern of immunity that should protect a population from invasion of a new infection. A common implication of the term is that the risk of infection among susceptible individuals in a population is reduced by the presence and proximity of immune individuals (this is sometimes referred to as \"indirect protection\" or a \"herd effect\"). We provide brief historical, epidemiologic, theoretical, and pragmatic public health perspectives on this concept.

Illegal wildlife trade has reached alarming levels globally, extirpating populations of commercially valuable species. As a driver of biodiversity loss, quantifying illegal harvest is essential for conservation and sociopolitical affairs but notoriously difficult. Here we combine field-based carcass monitoring with fine-scale demographic data from an intensively studied wild African elephant population in Samburu, Kenya, to partition mortality into natural and illegal causes. We then expand our analytical framework to model illegal killing rates and population trends of elephants at regional and continental scales using carcass data collected by a Convention on International Trade in Endangered Species program. At the intensively monitored site, illegal killing increased markedly after 2008 and was correlated strongly with the local black market ivory price and increased seizures of ivory destined for China. More broadly, results from application to continental data indicated illegal killing levels were unsustainable for the species between 2010 and 2012, peaking to ~8% in 2011 which extrapolates to ~40,000 elephants illegally killed and a probable species reduction of ~3% that year. Preliminary data from 2013 indicate o ver harvesting continued. In contrast to the rest of Africa, our analysis corroborates that Central African forest elephants experienced decline throughout the last decade. These results provide the most comprehensive assessment of illegal ivory harvest to date and confirm that current ivory consumption is not sustainable. Further, our approach provides a powerful basis to determine cryptic mortality and gain understanding of the demography of at-risk species.

Bumble bees (Bombus) are vitally important pollinators of wild plants and agricultural crops worldwide. Fragmentary observations, however, have suggested population declines in several North American species. Despite rising concern over these observations in the United States, highlighted in a recent National Academy of Sciences report, a national assessment of the geographic scope and possible causal factors of bumble bee decline is lacking. Here, we report results of a 3-y interdisciplinary study of changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. We compare current and historical distributions of eight species, compiling a database of >73,000 museum records for comparison with data from intensive nationwide surveys of >16,000 specimens. We show that the relative abundances of four species have declined by up to 96% and that their surveyed geographic ranges have contracted by 23–87%, some within the last 20 y. We also show that declining populations have significantly higher infection levels of the microsporidian pathogen Nosema bombi and lower genetic diversity compared with co-occurring populations of the stable (nondeclining) species. Higher pathogen prevalence and reduced genetic diversity are, thus, realistic predictors of these alarming patterns of decline in North America, although cause and effect remain uncertain.

The current biodiversity crisis encompasses a sixth mass extinction event affecting the entire class of amphibians. The infectious disease chytridiomycosis is considered one of the major drivers of global amphibian population decline and extinction and is thought to be caused by a single species of aquatic fungus, Batrachochytrium dendrobatidis. However, several amphibian population declines remain unexplained, among them a steep decrease in fire salamander populations (Salamandra salamandra) that has brought this species to the edge of local extinction. Here we isolated and characterized a unique chytrid fungus, Batrachochytrium salamandrivorans sp. nov., from this salamander population. This chytrid causes erosive skin disease and rapid mortality in experimentally infected fire salamanders and was present in skin lesions of salamanders found dead during the decline event. Together with the closely related B. dendrobatidis, this taxon forms a well-supported chytridiomycete clade, adapted to vertebrate hosts and highly pathogenic to amphibians. However, the lower thermal growth preference of B. salamandrivorans, compared with B. dendrobatidis, and resistance of midwife toads (Alytes obstetricans) to experimental infection with B. salamandrivorans suggest differential niche occupation of the two chytrid fungi.

Background. The impact of the 13-valent pneumococcal conjugate vaccine (PCV13) at the population level is unclear. We explored PCV13's effect in reducing invasive pneumococcal disease (IPD)–related morbidity and mortality, and whether serotype-specific changes were attributable to vaccination or expected as a part of natural, cyclical variations. Methods. This was a Danish nationwide population-based cohort study based on the linkage of laboratory surveillance data and the Danish Civil Registration System. Changes in IPD incidence and mortality during baseline (2000–2007), 7-valent pneumococcal conjugate vaccine (PCV7) (2008–2010), and PCV13 (2011–2013) periods were estimated. Predicted incidences of serotypes were estimated controlling for cyclical trends from historical patterns observed during the past 20 years. Results. We observed a 21% reduction (95% confidence interval [CI], 17%–25%) in IPD incidence in the total population after PCV13's introduction, and a 71% reduction (95% CI, 62%–79%) in children aged <2 years, considered as the vaccine effectiveness. We estimated a 28% reduction (95% CI, 18%–37%) in IPD-related 30-day mortality, from 3.4 deaths (95% CI, 3.2–3.6) per 100 000 population in the pre-PCV period to 2.4 (95% CI, 2.2–2.7) in the PCV13 period. The decline in mortality was observed across all age groups but was mainly related to mortality reductions in the nonvaccinated population. For serotypes 1 and 3, there were no significant changes in incidence beyond what would be expected from natural cyclical patterns. Serotype 19A significantly increased following PCV7's introduction, but the incidence declined toward baseline in 2012. Conclusions. PCV13 has brought greater benefits than we had expected in our setting. We observed a further decline on IPD incidence shortly after the shift from PCV7 to PCV13 in the national immunization program. This decline was accompanied by a substantial population-level decline in pneumococcal-related mortality of nearly 30% among nonvaccinated persons.

Objectives To estimate 10 year decline in cognitive function from longitudinal data in a middle aged cohort and to examine whether age cohorts can be compared with cross sectional data to infer the effect of age on cognitive decline. Design Prospective cohort study. At study inception in 1985-8, there were 10 308 participants, representing a recruitment rate of 73%. Setting Civil service departments in London, United Kingdom. Participants 5198 men and 2192 women, aged 45-70 at the beginning of cognitive testing in 1997-9. Main outcome measure Tests of memory, reasoning, vocabulary, and phonemic and semantic fluency, assessed three times over 10 years. Results All cognitive scores, except vocabulary, declined in all five age categories (age 45-49, 50-54, 55-59, 60-64, and 65-70 at baseline), with evidence of faster decline in older people. In men, the 10 year decline, shown as change/range of test×100, in reasoning was −3.6% (95% confidence interval −4.1% to −3.0%) in those aged 45-49 at baseline and −9.6% (−10.6% to −8.6%) in those aged 65-70. In women, the corresponding decline was −3.6% (−4.6% to −2.7%) and −7.4% (−9.1% to −5.7%). Comparisons of longitudinal and cross sectional effects of age suggest that the latter overestimate decline in women because of cohort differences in education. For example, in women aged 45-49 the longitudinal analysis showed reasoning to have declined by −3.6% (−4.5% to −2.8%) but the cross sectional effects suggested a decline of −11.4% (−14.0% to −8.9%). Conclusions Cognitive decline is already evident in middle age (age 45-49).

In February 2022, Russia invaded Ukraine, leading to severe population loss as millions exited the country and casualties mounted. However, population decline in Ukraine had been occurring for decades due to the triple burden of depopulation: low fertility, high mortality and substantial emigration. Ukraine had also already experienced years of armed conflict and large-scale displacement after the Russian-backed separatist movement, which started in 2014. This study investigates perspectives on depopulation using online focus groups conducted in July 2021, seven months before the current invasion. We compared discussions in eastern Ukraine, including in rural villages, the IDP-receiving city of Mariupol, the large city of Kharkiv and occupied Donetsk. Participants observed that cities were growing at the expense of rural areas. The situation in Donetsk was bleak due to mass emigration, but some participants pointed to a recent increase in births. Overall, the participants acknowledged the triple burden of depopulation in Ukraine, and the consequences of population decline, such as a shrinking labour force and rapid ageing.