Spatial distribution and determinants of intermittent preventive treatment for malaria during pregnancy: a secondary data analysis of the 2019 Ghana malaria indicators survey.

BACKGROUND: Malaria during pregnancy is associated with poor maternal, foetal, and neonatal outcomes. To prevent malaria infection during pregnancy, the World Health Organization recommended the use of intermittent preventive therapy with sulfadoxine-pyrimethamine (IPTp-SP) in addition to vector control strategies. Although Ghana's target is to ensure that all pregnant women receive at least three (optimal) doses of SP, the uptake of SP has remained low; between 2020 and 2022, only 60% of pregnant women received optimal SP during their most recent pregnancy. This study sought to map the geospatial distribution and identify factors associated with SP uptake during pregnancy in Ghana. METHODS: Secondary data analysis was conducted using the 2019 Ghana Malaria Indicator Survey dataset. The data analysed were restricted to women aged 15-49 years who reported having a live birth within the two years preceding the survey. A modified Poisson regression model was used to determine factors associated with SP uptake during pregnancy. Geospatial analysis was employed to map the spatial distribution of optimal SP uptake across the ten regions of Ghana using R software. RESULTS: The likelihood that pregnant women received optimal SP correlated with early initiation of first antenatal care (ANC), number of ANC contacts, woman's age, region of residence, and family size. Overall, the greater the number of ANC contacts, the more likely for pregnant women to receive optimal SP. Women with four or more ANC contacts were 2 times (aPR: 2.16; 95% CI: [1.34-3.25]) more likely to receive optimal SP than pregnant women with fewer than four ANC contacts. In addition, early initiation and a high number of ANC contacts were associated with a high number of times a pregnant woman received SP. Regarding spatial distribution, a high uptake of optimal SP was significantly observed in the Upper East and Upper West Regions, whereas the lowest was observed in the Eastern Region of Ghana. CONCLUSIONS: In Ghana, there were regional disparities in the uptake of SP during pregnancy, with the uptake mainly correlated with the provision of ANC services. To achieve the country's target for malaria control during pregnancy, there is a need to strengthen intermittent preventive treatment for malaria during pregnancy by prioritizing comprehensive ANC services.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health.

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

Urbanization reduces resource use efficiency of phytoplankton community by altering the environment and decreasing biodiversity.

Urbanization often exerts multiple effects on aquatic and terrestrial organisms, including changes in biodiversity, species composition and ecosystem functions. However, the impacts of urbanization on river phytoplankton in subtropical urbanizing watersheds remain largely unknown. Here, we explored the effects of urbanization on phytoplankton community structure (i.e., biomass, community composition and diversity) and function (i.e., resource use efficiency) in a subtropical river at watershed scale in southeast China over 6 years. A total of 318 phytoplankton species belonging into 120 genera and 7 phyla were identified from 108 samples. Bacillariophyta biomass showed an increasing trend with increasing urbanization level. The phytoplankton community shifted from Chlorophyta dominance in rural upstream waters to Bacillariophyta dominance in urbanized downstream waters. Furthermore, phytoplankton diversity and resource use efficiency (RUE = phytoplankton biomass/total phosphorus) were significantly decreased with increasing urbanization level from upstream to downstream. Phytoplankton RUE exhibited a significant positive correlation with species richness, but a negative correlation with phytoplankton evenness. The variation in environmental factors (turbidity, total nitrogen, NH4+-N, total phosphorus, PO43--P and percentage urbanized area) was significantly correlated with phytoplankton diversity and RUE. Overall, our results revealed the influence of urbanization on phytoplankton community structure and ecosystem function was due to its altering the environmental conditions. Therefore, human-driven urbanization may play crucial roles in shaping the structure and function of phytoplankton communities in subtropical rivers, and the mechanism of this process can provide important information for freshwater sustainable uses, watershed management and conservation.

Decomposition and decoupling analysis of carbon dioxide emissions in African countries during 1984‒2014.

The potential for mitigating climate change is growing worldwide, with an increasing emphasis on reducing CO2 emissions and minimising the impact on the environment. African continent is faced with the unique challenge of climate change whilst coping with extreme poverty, explosive population growth and economic difficulties. CO2 emission patterns in Africa are analysed in this study to understand primary CO2 sources and underlying driving forces further. Data are examined using gravity model, logarithmic mean divisia index and Tapio's decoupling indicator of CO2 emissions from economic development in 20 selected African countries during 1984-2014. Results reveal that CO2 emissions increased by 2.11% (453.73 million ton) over the research period. Gravity centre for African CO2 emissions had shifted towards the northeast direction. Population and economic growth were primary driving forces of CO2 emissions. Industrial structure and emission efficiency effects partially offset the growth of CO2 emissions. The economic growth effect was an offset factor in central African countries and Zimbabwe due to political instability and economic mismanagement. Industrial structure and emission efficiency were insufficient to decouple economic development from CO2 emissions and relieve the pressure of population explosion on CO2 emissions in Africa. Thus, future efforts in reducing CO2 emissions should focus on scale-up energy-efficient technologies, renewable energy update, emission pricing and long-term green development towards sustainable development goals by 2030.

Community responses of testate amoebae (Arcellinida and Euglyphida) to ecological disturbance explained by contrasting assembly mechanisms in two subtropical reservoirs.

Mechanisms underlying the effects of ecological disturbance on aquatic ecosystems remain uncertain in subtropical regions. Here, we used a proxy-based approach to explore the community dynamics of testate amoebae (Arcellinida and Euglyphida) in two subtropical deep reservoirs (Tingxi and Shidou) in Xiamen, southeastern China, over a three-year period. Specifically, we employed drought and typhoon events recorded by weather station as proxies for ecological disturbance and chlorophyll-a estimated through fluorometry as a proxy for testate amoeba food. We addressed three questions: (1) Does typhoon-induced ecological disturbance affect the distribution patterns of testate amoebae in subtropical reservoirs? (2) Do typhoon- and drought-induced ecological disturbances affect the testate amoeba community across different water layers of subtropical reservoirs similarly? (3) Do stochastic or deterministic processes shaping the testate amoeba community over time exhibit similar patterns in different water layers of subtropical reservoirs? The typhoon-induced ecological disturbance resulted in pronounced shifts in the distribution patterns of testate amoebae, characterized by lower shell influx in surface waters (11-12 ind. mL-1 d-1) and higher shell influx in middle and bottom waters (12-22 ind. mL-1 d-1). The impact of typhoon-and drought-induced ecological disturbance was more pronounced in surface waters, and its pure explanation accounted for 29.5-35.5 % community variation in a variation partitioning analysis. The effect of stochastic processes revealed by the neutral model increased with water depths, accounting for 63.3-76.5 % of the community variation in the surface, 77.4-82.6 % in the middle, and 82.8-88.1 % in the bottom water. The effect of deterministic processes shown by the null model decreased with water depth and remained relatively low across all water layers. These results suggest contrasting patterns of assembly mechanisms underlying the testate amoeba community responses to ecological disturbance, with the balance perhaps shaped by water depth and the average water residence time in a reservoir.

Population and molecular responses to warming in Netzelia tuberspinifera - An endemic and sensitive protist from East Asia.

With the effects of global warming becoming ever more obvious, biodiversity conservation is facing severe challenges. Currently, a deeper understanding the mechanisms of the effects of warming on sensitive species has become an important topic in aquatic biodiversity and ecological management. Our study first overcame the "challenge" for a sensitive indicator species (Netzelia tuberspinifera, an endemic testate amoeba species in East Asia) of culturing under laboratory conditions, and then explored its molecular response mechanisms to warming using transcriptomic analysis. Our data indicate that temperature mainly drove the geographical and seasonal variation of N. tuberspinifera populations. Transcriptomic results indicate that when the temperature is <25 °C, rising temperature triggers the biosynthesis of ribosomes; while the temperature is >25 °C, it triggers molecular processes related with cell division, test formation and general biomass increase. However, once the temperature exceeds 40 °C, N. tuberspinifera is unable to survive. Following from these results, the distribution of N. tuberspinifera might expand towards higher altitude or latitude regions under global warming. For the first time, our study showed direct evidence for sensitive protozoa species that presents a very narrow adaptation mechanism to local climate. Our work provides fundamental data for regional biodiversity conservation and scientific reference in subtropical and tropical waterbodies.

Evaluation and optimization of the influence of silver cluster ions on the MALDI-TOF-MS analysis of polystyrene nanoplastic polymers.

In the analysis of polystyrene nanoplastics (PSNs), a nonpolar polymer (NP), using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), silver salts were used as cationization reagents and simultaneously brought the potential problems of silver clusters that interfered with the PSN signal of MS. To detect PSNs, silver trifluoroacetate (AgTFA) and silver nitrate (AgNO3) were mixed with five polar matrices, namely 2-(4-hydroxyphenylazo) benzoic acid (HABA), dithranol (DI), sinapic acid (SA), trans-3-indoleacrylic acid (IAA), and 2,5-dihydroxybenzoic acid (DHB), and three nonpolar matrices, namely pyrene (PRN), anthracene (ATH) and acenaphthene (ACTH). The results showed that silver salt cluster ions were detected in the range of m/z 1000-4000. Five polar matrices with silver salts produced silver clusters, which interfered with the signals in the mass spectrum of PSNs, but the combination of these matrices with copper II chloride (CuCl2) salt did not produce copper-related clusters. However, the use of nonpolar matrices such as PRN, ATH or ACTH significantly decreased the signals of silver salt cluster ions, and this alteration of matrix types is considered a promising optimization approach for silver cluster ions. The nonpolar matrix conditions were optimized without producing silver cluster ions and the optimal detection conditions were found to be under nonpolar matrices (e.g., pyrene) with silver salts (e.g., AgTFA). The results suggest that when polar matrices, such as HABA, DI, SA, IAA, and DHB, are combined with silver salts in MALDI-TOF-MS analysis, silver-related clusters are detected in the range of m/z 1000-4000. Inhibition of the production of silver cluster ions can be achieved by the use of a nonpolar matrix (e.g., PRN) or polar matrix (e.g., DHB) with copper salts.

Responses of abundant and rare bacterioplankton to temporal change in a subtropical urban reservoir.

Investigation of bacterial community dynamics across different time scales is important for understanding how environmental conditions drive community change over time. Bacterioplankton from the surface waters of a subtropical urban reservoir in southeast China were analyzed through high-frequency sampling over 13 months to compare patterns and ecological processes between short (0‒8 weeks), medium (9‒24 weeks) and long (25‒53 weeks) time intervals. We classified the bacterial community into different subcommunities: abundant taxa (AT); conditionally rare taxa (CRT); rare taxa (RT). CRT contributed > 65% of the alpha-diversity, and temporal change of beta-diversities was more pronounced for AT and CRT than RT. The bacterial community exhibited a directional change in the short- and medium-time intervals and a convergent dynamic during the long-time interval due to a seasonal cycle. Cyanobacteria exhibited a strong succession pattern than other phyla. CRT accounted for > 76% of the network nodes in three stations. The bacteria-environment relationship and deterministic processes were stronger for large sample size at station G (n = 116) than small sample size at stations C (n = 12) and L (n = 22). These findings suggest that a high-frequency sampling approach can provide a better understanding on the time scales at which bacterioplankton can change fast between being abundant or rare, thus providing the facts about environmental factors driving microbial community dynamics. Patterns and processes in alpha- and beta-diversities and community assembly of bacterioplankton differ among different time intervals (short-, medium- and long-time intervals) and different subcommunities (abundant, conditionally rare and rare taxa) in a subtropical urban reservoir, demonstrating the importance of temporal scale and high-frequency sampling in microbial community ecology.

Decade-scale change in testate amoebae community primarily driven by anthropogenic disturbance than natural change in a large subtropical reservoir.

Understanding the extent of human activities leading to an influx of chemical pollutants that cause substantial environmental transformations is the focus of much ongoing research. In this study, we present a multi-proxy record based on a sediment core from a large subtropical reservoir (Xinfengjiang Reservoir) in south China with an emphasis on the changes in testate amoebae community, in combination with sedimentological (radioactivity, physicochemistry, nutrient and organochlorine pesticides) and climatological (air temperature and precipitation) data over the last three decades. Twenty-seven testate amoebae species belonging to seven genera (Arcella, Centropyxis, Cyclopyxis, Difflugia, Netzelia, Euglypha and Pseudodifflugia) were observed. Species richness, abundance and biomass of testate amoebae were in ranges of 18-26 species, 616-825 ind. ml-1 and 9.0-19.4 µg C ml-1, respectively. Two development stages of the reservoir, dated to 1978-1993 (stage 1) and 1993-2006 (stage 2), were distinguished based on testate amoebae communities. Stage 1 was characterized by elevated dry bulk density, carbon-to­nitrogen ratio and p,p'-DDE in the sediment core and an impact of nitrogen and sulfur deficiency on testate amoebae. Stage 2 was marked by a decrease of dry bulk density, elevated concentrations of aluminum, iron and carbon, low carbon-to­nitrogen ratio and organochlorine pesticides, fluctuations in rainfall on shorter and yearly timescales, and a stronger influence of the organochlorine pesticides on testate amoebae. Testate amoebae community change and the identified two-stage development were consistent with atmospheric deposition of organochlorine pesticides from anthropogenic sources inside and outside the reservoir watershed, nutrient influx and sediment physicochemistry. The testate amoebae community dynamics and a strong community-environment relationship in stage 2 were linked with non-random patterns in the biotic neighborhoods of species (deterministic processes). The results suggest a stronger impact of anthropogenic disturbance than natural environmental change on testate amoebae community variation of Xinfengjiang Reservoir over time.

Effects of natural and anthropogenic changes on testate amoebae communities in an alpine lake over the past 2500 years.

Deep high-altitude mountain lakes can act as a natural laboratory, and have the potential to contribute ecological data for understanding the way natural climate and anthropogenic changes that can affect the ecosystems. We present a multi-proxy record from a sediment core from such a lake (Lake Lugu) in southwest China with emphasis on the changes in the testate amoebae community, along with sedimentological data (magnetic susceptibility, total organic carbon/TOC and total nitrogen/TN) over the last 2500 years. In total, 29 testate amoebae species belonging to eight genera (Arcella, Centropyxis, Cyphoderia, Difflugia, Netzelia, Phryganella, Pseudodifflugia and Zivkovicia) were identified. Three stages were clearly defined for the lake based on testate amoebae community. The first stage dated to about 500 BCE-800 CE, with the testate amoebae community dominated by Centropyxis and influenced by soil erosion. The second stage (about 800-1920 CE) was characterized by a gradual increase of TOC and TN and an abrupt shift from Centropyxis-dominated to Difflugia-dominated communities. The third stage (about 1920-2010 CE) showed the pronounced impact of environmental change, high proliferation of Difflugia and a strong influence of human activities. Our results suggest that the testate amoebae assemblages in this high-altitude mountain lake are sensitive paleoenvironmental indicators that can help to monitor alpine lake ecosystem change and model lake succession under changing climate and environment. The potential causes of changes in the testate amoebae species composition and three stages of Lake Lugu succession were soil erosion and pollutants. The soil erosion led to the inwash of terrestrial particles and few testate amoebae species into Lake Lugu showing the importance of stochastic processes. The nutrient enrichment from soil erosion generated disturbances in the environment and species competition that led to the proliferation of some species and disappearance of others through niche based deterministic processes.

Morphology of testate amoeba Difflugia australis (Playfair, 1918) Gautier-Lièvre et Thomas, 1958 from a subtropical reservoir (southeast China).

Difflugia australis, first described by Playfair (1918), has a unique morphotype. However, in the absence of morphometric data, it has not yet been reliably classified within the largest testate amoeba genus Difflugia. In this study D. australis collected from a subtropical reservoir in southeast China was investigated by means of light and scanning electron microscopy. Basing on biometrical data, we provide an improved diagnosis of this little known species. Difflugia australis is different from other similar congeners (i.e., D. bacillariarum Perty, 1849 and D. elegans Penard, 1890) mainly by the combination of the following features: the shell is broadly ovate, with rounded dome and convex sides converging down to a very short distance from the aperture and diverging suddenly into a short rim (collar). It is usually more or less asymmetrical, with one side being more dilated than the other. The shell surface is slightly smooth, composed of flat siliceous plates of irregular shape and size, mixed with fine grains; microbial spores of comparable forms are spread on the shell surface; particles are often interspersed with a network of organic cement with unique mesh pattern; one (sometimes two) slanting spine-like posterior end of the shell is variable in form; collar is mainly formed by small plates of equal size. The dimensions of the shell are: total shell length 88-106 µm; shell width 53-88 µm; aperture diameter 19-28 µm; collar height 3-6 µm; spine length 3‒23 µm. The size frequency distributions of both total shell length and shell width indicate that it is a size-monomorphic species with low variability.

Temperature transfer functions based on freshwater testate amoebae from China.

Globally, lakes and reservoirs ecosystems are integral parts of ecological processes. Nevertheless, global warming is rapidly changing their function and sustainability, especially in the populated area of the northern hemisphere. Here we examined testate amoebae community and 10 environmental variables from 51 lakes and reservoirs across China and developed testate amoebae transfer functions for temperature based on both abundance- and biomass-datasets. A total of 169 testate amoebae taxa were identified. Our partial CCA analyses revealed that water temperature explained 5.15% (P = 0.006) and 5.57% (P = 0.008) of the total variance in testate amoebae abundance and biomass, respectively. The WA-PLS was the best model in abundance-based temperature transfer function (RMSEP = 2.87 °Ð¡, R2 = 0.60), whereas the MAT proved to be the best model for biomass-based temperature transfer function (RMSEP = 3.34 °Ð¡, R2 = 0.67). The application of all models should be carried out with suitable precautions. Our results suggested that freshwater testate amoebae could contribute to a better understanding of the ecological integrity and its vulnerability in inland aquatic environments.