Decline In Abundance Research Articles

The immune landscape of fetal chorionic villous tissue in term placenta

IntroductionThe immune compartment within fetal chorionic villi is comprised of fetal Hofbauer cells (HBC) and invading placenta-associated maternal monocytes and macrophages (PAMM). Recent studies have characterized the transcriptional profile of the first trimester (T1) placenta; however, the phenotypic and functional diversity of chorionic villous immune cells at term (T3) remain poorly understood.MethodsTo address this knowledge gap, immune cells from human chorionic villous tissues obtained from full-term, uncomplicated pregnancies were deeply phenotyped using a combination of flow cytometry, single-cell RNA sequencing (scRNA-seq, CITE-seq) and chromatin accessibility profiling (snATAC-seq).ResultsOur results indicate that, relative to the first trimester, the frequency of fetal macrophages (HBC, proliferating HBC) is significantly reduced, whereas that of infiltrating maternal monocytes/macrophages (PAMM1b, PAMM1a, PAMM2, MAC_1) increased in T3. PAMM1b and HBCs exhibit the most phagocytic capacity at term highlighting their regulatory role in tissue homeostasis in late pregnancy. The transcriptional profiles of resident villous immune subsets exhibit a heightened activation state relative to the relative to T1, likely to support labor and parturition. Additionally, we provide one of the first insights into the chromatin accessibility profile of villous myeloid cells at term. We next stratified our findings by pre-pregnancy BMI since maternal pregravid obesity is associated with several adverse pregnancy outcomes. Pregravid obesity increased inflammatory gene expression, particularly among HBC and PAMM1a subsets, but dampened the expression of antimicrobial genes, supporting a tolerant-like phenotype of chorionic villous myeloid cells. We report a decline in HBC abundance accompanied by an increase in infiltrating maternal macrophages, which aligns with reports of heightened chorionic villous inflammatory pathologies with pregravid obesity. Finally, given the shared fetal yolk-sac origin of HBCs and microglia, we leveraged an in vitro model of umbilical cord blood-derived microglia to investigate the impact of pregravid obesity on fetal neurodevelopment. Our findings reveal increased expression of activation markers albeit dampened phagocytic capacity in microglia with pregravid obesity.DiscussionOverall, our study highlights immune adaptations in the fetal chorionic villous with gestational age and pregravid obesity, as well as insight towards microglia dysfunction possibly underlying poor neurodevelopmental outcomes in offspring of women with pregravid obesity.

EXPLORING THE LINK BETWEEN WATER CHEMISTRY VARIATION AND FISH DIVERSITY IN RIVER JHELUM: A META-ANALYSIS

This study aimed to establish a connection between changes in the water chemistry of the river Jhelum and the diversity, richness, and abundance of species over time. Empirical evidence was reviewed from existing literature on fish species diversity and physicochemical parameters. A comparison was made between the upper and lower sections of the river, considering both spatial and temporal aspects. The dominant fish family in the river was Cyprinidae, consisting of eight species, followed by Nemachilidae, with only two species. Regarding diversity indices, the upper stretch exhibited values of 2.192 for the Shannon-Wiener diversity index (H'), 0.104 for Simpson's dominance index (D), 0.896 for the heterogeneity index (1-D), 1.436 for Margalef's index (d), and 0.350 for Pielou's evenness index (J'). Conversely, the lower stretch showed values of 1.978, 0.145, 0.855, 1.144, and 0.323, respectively. These findings indicated a decline in fish species diversity, richness, and relative abundance in the lower section. These results align with existing literature, suggesting that water pollution is more severe in the lower stretch compared to the upper stretch. However, correlation analysis revealed that, except for dissolved oxygen and ortho phosphorous, there is a negative relationship between water quality parameters and fish diversity, which, while present, is not significant enough to impact the river's fish diversity substantially. This suggests that other anthropogenic activities, such as sand mining, overfishing, and exotic common carp in the river, are responsible for the decreased fish diversity downstream in the river Jhelum. Further research is needed to investigate the effects of other hydrological parameters, such as precipitation, evapotranspiration, surface runoff, water velocity, and depth, on the fish diversity of the river Jhelum. Such studies would provide additional empirical evidence for protecting the aquatic fish biodiversity in the river Jhelum.

A Colorado Front Range grassland exhibits decreasing dominance of cheatgrass (Bromus tectorum) over time

AbstractCauses, consequences, and potentials for recovery from invasions by the invasive annual grass, cheatgrass (Bromus tectorum), in western North America have been extensively documented. The vast majority of these studies have come from regions where yearly precipitation is dominated by “winter‐wet” patterns, but this species has also demonstrated its ability to invade plant communities in “spring/summer‐wet” areas as well. In grasslands of the Front Range of Colorado, a region experiencing a “spring/summer‐wet” precipitation pattern, cheatgrass can exploit early‐season soil moisture, but moderate rainfall continues into the growing season beyond the time of cheatgrass senescence. In this study, we measured how cheatgrass dominance changed over a 13‐year interval in a disturbed meadow along the Front Range of Colorado with a “spring/summer‐wet” precipitation pattern. Cheatgrass cover declined in absolute abundance by about 50% while total vegetation cover increased over this time period. The site was neither grazed nor burned during this interval. A “spring/summer‐wet” precipitation pattern with high interannual variation in amounts occurred during the study, but no relationships between the seasonality or amounts of precipitation and the directional decline in cheatgrass abundance were observed. Rainout shelter manipulations showed that the seasonality of precipitation influenced cheatgrass abundance, with winter drought treatments reducing cheatgrass cover relative to plots that experienced summer drought treatments. The cheatgrass decline corresponded with a lesser decline in native grass cover and no change in native forb cover, while the abundance of non‐native perennial grasses and forb species increased over the study interval. Although cheatgrass can invade communities across broad climatic gradients following disturbance, results from this study show that the persistence of cheatgrass within invaded areas may depend on the seasonality of precipitation and plant communities that vary across these gradients.

Can Cryptogonimids of the Same Genus Influence Each Other’s Level of Genetic Variation?

Trematodes of the genus Exorchis are parasites that are common in East and Southeast Asia. These parasites are known to infect fish, thus impacting aquaculture significantly. An introspection into the dynamics of infection of these parasites has revealed possible co-infection in shared hosts. But data on the dynamics of their shared host on their population structure and genetic variability is lacking. In this study, we investigate the intraspecific structure of the Exorchis species, Exorchis oviformis, and E. convictus, both of which coexist in the same definitive host. By using partial gene sequences of the mitochondrial cox1 gene (715 bp), including 30 newly obtained sequences from the southern part of the Russian Far East, we found a low level of genetic variation in both species, consistent with previous findings of other trematodes from the same region. We hypothesize that the observed low variability could be attributable to the process of host infection and transmission and abiotic factors influencing a recent decline in host variability and abundance. This is driving a strong selection pressure due to the limited number of parasites reaching the definitive host. This, among other factors, could possibly impact the long-term survival and adaptability of Exorchis and other trematodes at large in the region. However, we also believe that there may be a chance that these closely related species could exert an influence on each other’s genetic diversity, potentially limiting the variation within each species. To uncover the dynamics driving these observations, we propose the approach of expanding sampling, broader genetic marker analyses, and investigations of varied host populations that could elucidate the complexities of the Exorchis species genetic variability and evolutionary dynamics.

Assessing changes in threatened black rockcod Epinephelus daemelii abundance and length over the past 15 years in New South Wales, Australia.

Ideally, protection of a threatened fish will lead to their recovery in abundance, distribution, and size structure within the population, to a point where they are no longer considered threatened. Monitoring abundance and size is crucial to evaluate this, although low numbers associated with being threatened can strongly constrain the methods used. To assess if population recovery is occurring for the black rockcod Epinephelus daemelii, a large subtropical grouper endemic to shallow reefs in the southwest Pacific, surveys were undertaken across northern New South Wales and Lord Howe Island using roving diver timed counts and diver stereo-video measurements to assess relative abundance and length. Surveys in 2023 were compared with initial baseline data captured in 2009-2011 using the same methods. Relative abundance of E. daemelii at long-term monitoring sites has remained relatively constant or declined since 2010 rather than increasing. Comparisons between 84 broadscale sites in 2009-2011 versus 2023 (117 vs. 69 observed E. daemelii) indicate a recent decline in abundance. Although protected from fishing and spearfishing for over 40 years, the relative abundance of E. daemelii does not appear to be increasing over the past 15 years since monitoring commenced. This is a concerning trend that does not indicate recovery, although an increase in the proportion of mature females in the population from 2010 to 2023 is positive. As E. daemelii is slow growing, long lived, late to mature and still susceptible to incidental capture mortality, more active management may be needed to help assist with the slow recovery of this threatened species.

Bumblebee Abundance in Species-Rich Grasslands in Southern Sweden Decreases with Increasing Amount of Arable Land at a Landscape Level.

Conservation of bumblebee populations is essential because of their role as pollinators. Declines in bumblebee abundance have been documented in recent decades, mostly attributed to agricultural intensification, landscape simplification and loss of semi-natural grasslands. In this study, we investigated the effects of landscape composition on bumblebee abundance at different spatial scales in 476 semi-natural grassland sites in southern Sweden. The area of arable land had a negative effect on total bumblebee abundance at all scales. This was most pronounced for short-tongued bumblebees, species typical of forested landscapes, and species with medium to large colony sizes and early queen emergence. The area of semi-natural grassland had a clear negative effect up to 1 km, affecting short-tongued bumblebees in both forested and agricultural landscapes and species with medium colony sizes and early queen emergence. The negative effect of arable land on bumblebees calls for action to adapt farming practices to ensure their conservation, e.g., by reducing pesticide use, improving crop diversity and promoting the presence of floral resources and alternative bumblebee habitats, such as species-rich field margins.

Great Lakes mallard population dynamics

AbstractBreeding mallard (Anas platyrhynchos) populations in the Great Lakes region (Michigan, Minnesota, Wisconsin, USA) declined by >40% between 2000–2022 based on abundance data collected during spring aerial surveys. Mallards are an important waterfowl species in this region, where an estimated 60–80% of the mallard harvest is composed of locally banded birds. Extensive population monitoring datasets are available for mallards, presenting an opportunity to address complex questions such as estimating productivity at large spatial and temporal scales, identifying the effects of harvest on mallard demography, quantifying mechanisms for harvest compensation, and integrating multiple datasets to quantify the demographic drivers of population change. Our objective was to simultaneously examine factors affecting demographic parameters and their relative contribution to Great Lakes mallard population dynamics. We used 32 years of banding, band recovery, and aerial survey data collected for mallards from Michigan and Wisconsin to develop an integrated population model (IPM). We used age ratios at banding to estimate productivity, band recoveries from hunter‐harvested birds to estimate annual survival and cause‐specific mortality (i.e., harvest or non‐hunting), and modeled abundance using aerial survey and demographic parameter estimates from 1991–2022. The IPM results indicated the decline in Great Lakes mallard abundance was caused by increased non‐hunting mortality and a decline in productivity. Productivity varied spatially but temporally declined with the loss of Conservation Reserve Program area. Moreover, our productivity assessment provided evidence of density dependence in reproduction. Non‐hunting mortality was 3.5–6.7 times and 1.3–4.2 times greater than harvest mortality for adult and juvenile female mallards, respectively, indicating environmental factors during spring and summer, not harvest, most greatly influenced annual mortality for female mallards. Our IPM reduced uncertainty in the factors affecting Great Lakes mallard population dynamics and indicated management actions that address non‐hunting mortality and productivity would be most effective in increasing Great Lakes mallard abundance.

Are COVID-19’s medications ecotoxic for free-living marine nematodes? Experimental assessment through separate and combined treatments with Miglustat and Migalastat

Miglustat (MGU) and migalastat (MLA) are commonly used to treat two rare lysosomal disorders, namely Gaucher's and Fabry's diseases, but lately suggested as cures for the COVID-19 disease. The impact of both drugs on meiobenthic nematodes was tested in laboratory conditions for 15 and 30 days. As such, nine treatments were used, targeting nematodes collected from Jeddah coasts (Saudi Arabia), and based on a control treatment and two concentrations (1.45 and 2.9mg.l-1) of MGU and MLA, applied separately or combined. The findings showed a decline in nematode abundance in all treatments, particularly within the MGU2/MLA2 community. Moreover, the results obtained showed that Daptonema aegypticum was a positive bioindicative species for MGU, and D. oxycerca and Longicyatholaimus longicaudatus were positive bioindicative taxa for MLA. Moreover, when combined, the mixtures induced multifaceted effects in the functional traits composition, revealing complex synergic interactions at the community level.

Abundance and distribution of larval and early juvenile fish in Puck Lagoon and outer Puck Bay in the southern Baltic Sea

Puck Bay, regarded as a crucial region along the Polish coastline, has witnessed a decline in fish taxa diversity and abundance over the past several years. The objective of this study was to ascertain the abundance and geographical distribution of fish larvae in Puck Lagoon and outer Puck Bay over the period from April to the end of September. A neuston net with a 300-μm mesh was utilized at 10–15 stations situated in the shallow coastal waters of the study area. A total of 13 taxa were identified among the larvae captured. The majority of larvae observed during the entire study period were identified as Gobiidae. Furthermore, the most abundant taxa were three-spined stickleback, broad-nosed pipefish, straight-nosed pipefish, Ammodytidae, and sprat. The presence of larvae belonging to other taxa, including herring, flounder, cod, turbot, fourbeard rockling, and roach, was observed on a sporadic basis. Details such as Shanon’s diversity Index, the month of larval presence, geographical distribution, and differences in abundance and body size between Puck Lagoon and outer Puck Bay were recorded. The findings indicated that the study area was characterized by a limited diversity of fish taxa. Furthermore, the majority of these taxa (e.g., Gobiidae, broadnose and straight-nosed pipefishes) are not the subject of fishing activities. Nevertheless, they serve as a food source for other taxa and are integral to the ecological balance of the ecosystem. It can thus be concluded that Puck Lagoon and the outer Puck Bay constitute an important habitat for non-commercial and commercial fish taxa.

Impacts of habitat loss by reservoir inundation on occurrence, abundance, and genetic diversity of an imperiled, river-adapted, benthic-specialist fish, Etheostoma lemniscatum (Tuxedo Darter)

AbstractDams homogenize habitat and alter natural depth and flow regimes of lotic habitats, leading to extirpation of many stream-adapted fishes such as darters (Percidae). The Tuxedo Darter, Etheostoma lemniscatum, is a habitat-specialist of shallow, flowing pools with cobble substrate in the Big South Fork Cumberland River. One threat to this species is Wolf Creek Dam on the Cumberland River that creates Lake Cumberland, which during summer pool, inundates the lower 72 river kilometers (rkms) of the Big South Fork. A six-year period of lower reservoir elevations for dam repairs allowed a 9 rkm reach to return to riverine habitat and E. lemniscatum to colonize this reach. Once dam repairs were complete, the lower 72 rkms were again regularly inundated by Lake Cumberland. To determine the impact of post-dam repair inundation on E. lemniscatum, we compared occurrence, abundance, and genetic diversity metrics estimated from samples from 2015 and from several years post-inundation in 2019 and 2020 from 11 sites spanning the species’ range. Declines in occurrence and abundance were detected within the re-inundated reach. We observed low genetic diversity for the species for both sample periods, but no significant changes in genetic diversity between years. A trend towards lower allelic richness and an increase in the proportion of private alleles was observed in the 2019/2020 samples. Coupled with local extirpation and declines in abundance, these trends may be early warning signs of future declines in genetic diversity. We suggest future genetic monitoring to identify any time delayed responses to inundation not detected herein.

Do penguins care about their neighborhood? Population implications of bioerosion in Magellanic penguin, Spheniscus magellanicus, at Martillo Island, Beagle Channel, Argentina.

Intrinsic and extrinsic factors, such as bioerosion at nesting sites, regulate population dynamics and are relevant for the long-term conservation of penguins. Colony trends (between 2004-2022) were studied in a Magellanic penguin colony on Martillo Island, Beagle Channel, Argentina and compared between zones with contrasting degrees of erosion (high, medium, low). Individuals from each zone were characterized for foraging ecology, stress, and reproductive performance during the 2017-2018 breeding season to better understand the colony dynamics. Changes in nest abundance varied in magnitude between nesting zones with different characteristics of occupation time, density and erosion. Declines in nest abundance in the densest, most eroded and longest occupied zone suggests that environmental degradation may be limiting the colony's carrying capacity. A higher percentage of late breeders (probably younger breeders) occupied the less eroded and more recently occupied zone. Foraging, breeding and stress barely differed between zones. New individuals recruiting into the breeding colony select less-eroded zones, either to reduce competition for nests or to avoid other effects of erosion and high-density areas. If this is the mechanism behind the shift in numbers throughout the island, we expect the island to be progressively occupied to the west. If competition or other density dependent factors are at play, a time will come when the vacant east side will begin to be recolonized by younger individuals. However, if erosion or other long-term effects spread throughout the island, recolonization may not occur and the colony may ultimately be abandoned as individuals search for new breeding grounds. Erosion at the breeding site may be a key factor in regional population trends of this burrow nesting species, by following an extinction / colonization of new sites process.

Structural and acoustic properties of urbanized landscapes adversely affect bird communities in a tropical environment

IntroductionThe rural-urban gradient serves as a valuable context for investigating the impact of urbanization on biodiversity. While previous studies have demonstrated shifts in bird communities along this gradient, our understanding of the specific impacts of individual urban components such as man-made physical structures and anthropogenic noise along this gradient remains limited, and more so, in Afro-tropical environments.MethodEmploying the point count method, we recorded birds and also determined the levels of anthropogenic noise and physical structures, across fifteen sites along the rural-urban gradient on the Jos Plateau, Nigeria. We then investigated variations in bird communities along the urbanization gradient and assessed the influence of the two urban components -anthropogenic noise and physical structures, on bird populations.ResultsThere was a decline in bird abundance and species richness along the urbanization gradient. Similarly, species common to all the urbanization categories (species present at least at one point in rural, suburban, and urban) also exhibited a decrease in abundance. The suburban area showed a greater similarity in bird community composition to the urban area than the rural area. Notably, as the level of urban development increased, numerous bird species associated with undisturbed sites gradually vanished. Both anthropogenic noise and physical structures exhibited significant negative effects on bird abundance and species richness. Interestingly, we did not find evidence to suggest that the impact of anthropogenic noise was dependent on the level of physical structures. Anthropogenic noise had a significant negative relationship with bird abundance and species richness at all levels of physical structures.DiscussionWe provide evidence that bird abundance and species richness respond negatively to urbanization-related increase in anthropogenic noise and physical structures. That the impact of anthropogenic noise on birds was independent of physical structures suggests that birds in reserved areas, including urban green areas with fewer human activities may equally be affected by noise as are birds in human-dominated areas, if noise sources are near. Overall, our research underscores the detrimental consequences of anthropogenic habitat modification, particularly the alteration of structural and acoustic properties, and emphasizes the importance of preserving undisturbed habitats and implementing ecologically mindful urban planning strategies to safeguard bird communities in the Afro-tropics.

Species traits explaining long-term abundance changes of breeding birds in farmland areas in Álava (N Spain)

In recent decades, the populations of many common bird species have greatly declined in Europe, particularly in farmland habitats. However, this decline has not affected every species, and to understand the mechanisms behind this interspecific variability, its relationship with several species-specific traits has been studied repeatedly. We used this approach to analyse long-term changes in the abundance of breeding passerines in farmland areas in northern Spain. Abundance changes were quantified in 2015 and 2016 by repeating the same line transects conducted in 1988/89 in three agricultural habitats located along a steep Atlantic-Mediterranean gradient in the province of Álava. We found that total bird abundance did not decline, as most species not closely linked to farmland habitats showed positive population changes, while the number of increasing and decreasing farmland specialists was similar. Specific traits explained a substantial proportion of the variability in abundance change, as warm-dwelling species and those occupying habitats with a complex vegetation structure showed more positive changes than those preferring colder conditions and more open habitats. These patterns can be explained by climate warming and by the increase in hedge and forest cover in the study area. Although we did not find a long-term decline in the overall abundance of the studied bird community nor in that of farmland specialists, open habitat species associated with a cool climate should be the focus of particular concern.

Characterizing the oral and gastrointestinal microbiome associated with healthy aging: insights from long-lived populations in Northeastern China.

The oral and gastrointestinal (GI) tract microbiota in humans is susceptible to geographical influences and represents vital factors impacting healthy aging. The northeastern region of China, characterized by distinct dietary and climatic conditions, significantly influences the human microbiome composition. However, the microbial structure of the entire long-lived population in this area has not been evaluated. This study recruited a cohort of 142 individuals aged 55-102 residing in Northeast China, and their oral and gut microbiota were evaluated using full-length 16S rRNA gene amplicon sequencing. The results indicate that the oral and GI tract microbiota of long-lived individuals showed reduced microbial taxonomic richness and evenness compared to sub-longevity individuals. With aging, the core species experience a gradual decline in abundance, while subordinate species show an increase. The long-lived population exhibited a heightened ability to enrich beneficial bacteria including Akkermansia, Alistipes, Parabacteroides, and Eubacterium coprostanoligenes in the GI tract, which are associated with host metabolism and have the potential to act as probiotics, reducing the risks of unhealthy aging in the northeast population. Bifidobacterium sp. and Lactobacillus salivarius have been found to coexist in both the oral cavity and the GI tract of long-lived individuals. We hypothesize that beneficial bacterial taxa from the oral cavity colonize the GI tract more extensively in long-lived individuals compared to those with a shorter lifespan. These findings pave the way for identifying probiotic strains that can promote healthy aging in Northeast China.

Air injection in paddy soil reduces N2O and NH3 emissions and regulates the nitrogen cycle

Rice (Oryza sativa L.) is a staple food and a significant source of pollutant gases, such as nitrous oxide (N2O) and ammonia (NH3). While aeration irrigation can significantly increase rice yield, its impact on N2O and NH3 emissions, particularly the nitrogen (N) cycling mechanisms, remains unclear. Here, we analyzed the effects of soil air injection (SAI) on N2O and NH3 emissions, soil properties, rice N uptake and microbial N cycling, compared with soil without air injection (the control). SAI increased soil oxygen diffusion rate (SODR) by 31–107 %, raised soil pH by 0.4–0.9 units, enhanced total N uptake by rice by 8.3 %, and reduced N2O emissions by 17 % and NH3 volatilization by 16 %. The increase in SODR enhanced the N content in rice leaves, which subsequently suppressed NH3 volatilization. The reduction in N2O emissions was mainly attributed to the decline in norC gene abundance, while the increased abundances of amoB and GDH1 genes contributed to the suppression of NH3 volatilization. The abundance of norC was negatively correlated with Actinobacteria, whereas amoB and GDH1 abundances were positively correlated with Thaumarchaeota and Proteobacteria, respectively. Actinobacteria abundance initially increased and then decreased with rising SODR, while Thaumarchaeota abundance consistently increased as SODR rose. Additionally, the increase in soil pH promoted the abundance of Proteobacteria. In conclusion, SAI increased N uptake in rice leaves and influenced key N-cycling microorganisms (Actinobacteria, Thaumarchaeota, and Proteobacteria) and genes (norC, amoB and GDH1) by enhancing SODR and soil pH, thereby reducing N2O and NH3 emissions.

Can microplastics variability drive the colonization dynamics of periphytic protozoan fauna in marine environments?

In recent years, microplastics have become a global environmental hot topic of concern. To explore the effects of different concentrations of microplastics on colonization dynamics of periphytic protozoan fauna, a 21-day study was conducted in temperature-controlled circulation systems. Periphytic protozoan communities were used as test organisms and exposed to five concentrations of MPs: 0, 1, 5, 25, and 125 mg l−1, identification and enumeration were conducted on days 3, 5, 7, 10, 14 and 21. The results showed that the colonization dynamics were driven by MPs and significantly shifted at concentrations over 5 mg l−1. However, a notable decline in maximum species richness and abundance was observed in the high concentrations of microplastic, along with significant deviations in colonization patterns from the control group (0 mg l−1). Therefore, it is suggested that the colonization dynamics of periphytic protozoa can serve as a bioindicator for assessing microplastic concentrations in marine environments.

Strong decline in grasshopper abundance over 20 years without major land-use changes: Is soil drying one of the drivers?

Strong declines in insect numbers have been described for different taxa and regions. These observations are of great concern such that broad scientific and public attention has been raised. Among other urgencies, the need for long-term insect data has been identified. Here, we present data on grasshopper (Caelifera) abundances recorded between 1992 and 2011 at over 600 sites in north-western Switzerland. While vegetation type, often semi-natural grasslands, had remained largely constant, total grasshopper abundance declined by around 50 % (while many other taxa showed much less decline). Numbers in July remained relatively stable until about 2003 but then declined similar to the declines seen in August–October already before. Greatest losses were observed for drier habitats and steeper slopes, suggesting that soil drying might be an important factor for the decline. Second, more nutrient-rich habitats suffered greater losses; possible reasons for this include small-scale vegetation changes in these habitats e.g. due to atmospheric nitrogen deposition, or isolation of sites. Other than abundance, species richness decreased much less, illustrating that important ecological changes may be strongly underestimated when only species lists are available. The strong declines at our sites, which often are in an agri-environmental scheme, is alarming. Apart from being yet another call to fight climate change, our results also point to the urgent need to reduce atmospheric nitrogen deposition and to continue extensive farming, but also to adapt it in preparation of expected effects of climate change, with the aim to favour a divers, ecologically robust insect community.

Sulfur dioxide sources in the stratosphere

Version 5.2 SO2 data from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) in low Earth orbit are used to determine global altitude–latitude abundance distributions. This new data set has SO2 volume mixing ratios (VMRs) from 11.5 to 39.5 km in altitude from February 2004 to July 2023. The average background SO2 abundance is plotted along with the abundance for four different seasons. These distributions show that there is a stratospheric source of SO2 that comes from the decline in sulfate aerosol abundance with increasing altitude. The visible and near-infrared photolysis of sulfuric acid (H2SO4) is the primary source of SO2 in the middle stratosphere. There is also a source of SO2 in the upper stratosphere and mesosphere. The Brewer-Dobson circulation enhances SO2 at higher altitudes, particularly by descent near the winter pole. The elevated abundance of SO2 near the poles originates from meteoric sources as well as UV photolysis of H2SO4 in the mesosphere. Large volcanic eruptions release sulfur dioxide (SO2) into the lower stratosphere, where it persists for several months.

Pengaruh Kualitas Air terhadap Keanekaragaman Plankton di Bozem: Analisis Parameter Fisik, Kimia, dan Biologi Ekosistem Perairan

Water quality plays an important role in maintaining the balance of aquatic ecosystems, including the abundance and diversity of plankton. This study aims to analyze the effect of various water quality parameters such as temperature, dissolved oxygen (DO), carbon dioxide (CO2) levels, Biochemical Oxygen Demand (BOD), pH, brightness, and turbidity on plankton diversity in Bozem. Data were obtained from eight observation stations with water quality parameter measurements and plankton sampling. The results showed that the water quality in Bozem was not optimal, with low DO values ​​(1.79 mg/L), high water temperatures (average 31.05°C), and low brightness (0.30 m), which contributed to the decline in plankton abundance. A total of 39 plankton genera were identified, with Synedra as the most dominant genus. Poor water quality inhibits plankton growth, which can impact the balance of the food chain in these waters. This study shows the importance of better water quality management to maintain the sustainability of aquatic ecosystems in Bozem. This study also contributes to the understanding of the multifactorial interactions between water quality parameters and plankton.

Different life strategies of closely related louse species in sympatry: specialist and “generalist“ lineages of Polyplax serrata

The origin and significance of host specificity are intriguing questions in parasitology. In the case of single-host versus multiple-host parasites, this topic integrates with the concept of the specialist/generalist trade-off. We use the model of sucking lice Polyplax serrata and rodent hosts Apodemus, to address these concepts. Polyplax serrata was shown to form a complex genetic structure, with a strictly specific S lineage living on Apodemus flavicollis, and a less specific N lineage on A. flavicollis and Apodemus sylvaticus. Moreover, the S lineage formed two mitochondrial clades with geographically exclusive distributions and a narrow hybrid zone, providing an opportunity to test the hypothesis that hybrids suffer a decrease in fitness. We sampled 451 individual lice from two host species at 103 localities. We used prevalences and intensities as proxies of fitness, which the parasites realize on their host. The S lineage, strictly specific to Apodemus flavicollis, reached significantly higher prevalences and intensities on its host compared with the N lineage. Conversely, the N lineage occurred with high prevalence and intensity on A. sylvaticus but tended to use also A. flavicollis when the louse populations became too dense. We discuss possible mechanisms behind this difference (particularly interspecific competition as a typical phenomenon in the specialist/generalist systems). We conclude that a parasite’s “choice”, not accessibility of the host or interspecific competition, is the main factor affecting the louse prevalences. We suggest that historical differences in geographic distribution of both lice and mice may provide a possible explanation for the observed life strategy differences. In contrast to the convincing picture in S and N lineage prevalences, we did not detect an expected drop in fitness in hybrids. We consider instability of the hybrid zone, or decline in abundance of the respective hosts, as possible explanations for this result.