Tropical Zone Research Articles

Dengue Fever—Diagnosis, Risk Stratification, and Treatment.

Dengue fever is a common infectious disease in the tropical and subtropical zones, with more than 100 million symptomatic cases per year. Mosquitoes of the genus Aedes (Aedes aegypti, Aedes albopticus) are vectors of the disease, and their spread has led to rising case numbers around the world. Physicians in Europe, too, are increasingly being confronted by this challenge. This review is based on the findings of a selective search in international publication databases, as well as on the WHO guideline of 2009 and the current recommendations of the Robert Koch Institute. Dengue fever takes a mild course in more than 90% of cases. Severe dengue fever, up to and including shock and/or mucosal hemorrhages, is rare and carries a mortality of 1-5%. The disease characteristically takes a triphasic course (febrile phase, critical phase, recovery phase). It is diagnosed by the direct demonstration of the pathogen (e.g., with the reverse transcriptase polymerase chain reaction [RT-PCR] up to day 5 of the illness) or by serology. Patients are classified into one of three risk groups depending on their findings and comorbidities and are then treated either as outpatients or in the hospital. The treatment is symptomatic, as no treatment directed against the cause of the disease is available. The key measures are adequate volume replacement and, in patients with hemorrhage, the transfusion of blood products. Preventive steps include vaccination after a documented initial infection and the meticulous avoidance of mosquito bites. Climate change and global mobility have led to a worldwide increase in dengue fever. The disease only rarely takes a severe course. In such cases, rapid symptomatic treatment as needed is the key to the avoidance of severe complications.

ESPOROTRICOSE FELINA

Sporotrichosis is a zoonotic disease caused by dimorphic fungi of the Sporothrix schenckii complex. Cats, due to their semi-domiciled lifestyle and species-specific behaviors, are most affected. Transmission occurs mainly through direct contact with infected animals, through scratches or bites, in addition to contact with the agent in the environment, such as contaminated soil and plants. The disease is more prevalent in countries in tropical and subtropical zones, with subcutaneous mycosis being more common in Latin America. Although the prognosis is generally favorable, sporotrichosis has become a growing public health problem, due to its expansion in regions of Brazil and the fact that it is a zoonosis. In humans, especially in immunosuppressed individuals, it can evolve into extracutaneous forms, with a risk of becoming fatal. Early diagnosis of sporotrichosis is essential for the prevention and control of this disease in Brazil.

Effects of Temperature, Dissolved Oxygen Concentration, and Photosynthetic Photon Flux Density on the Growth of the Sea Bivalve Tridacna crocea in Combination with the Symbiotic Alga Zooxanthella

The sea bivalve clam Tridacna crocea inhabiting the shallow sea of tropical and subtropical zones lives with the symbiotic alga zooxanthella in its mantle. Zooxanthellae algae perform photosynthesis and supply nutrients to T. crocea. Recently, the abundance of T. crocea has decreased rapidly due to overfishing in coastal areas in Okinawa, Japan. T. crocea culture systems for mass production will contribute to the conservation of T. crocea and thus marine ecosystems. Environmental control methods for T. crocea culture have not been established because of a lack of knowledge about the appropriate environmental conditions for T. crocea growth. The present study was initiated to obtain basic data for developing environmental control methods for T. crocea land-based aquaculture. The effects of water temperature, dissolved oxygen concentration, and photosynthetic photon flux density (PPFD) on the O2 exchange rates of the symbiotic system of T. crocea and zooxanthella, which are indicators of photosynthesis and respiration in the system, and the effect of daily integrated PPFD on T. crocea growth were investigated. Basic knowledge was obtained for the development of optimal environmental control technology for T. crocea clam culture. The optimum water temperature and dissolved oxygen concentration for photosynthesis in this symbiotic system were 28 °C, 5–6 mgO2 L−1 and 500 μmol m−2 d−1, respectively. The optimum daily integrated PPFD for clam growth was 20 mol m−2 d−1.

Harnessing genomic technologies for one health solutions in the tropics.

The targeted application of cutting-edge high-throughput molecular data technologies provides an enormous opportunity to address key health, economic and environmental issues in the tropics within the One Health framework. The Earth's tropical regions are projected to contain > 50% of the world's population by 2050 coupled with 80% of its biodiversity however these regions are relatively less developed economically, with agricultural productivity substantially lower than temperate zones, a large percentage of its population having limited health care options and much of its biodiversity understudied and undescribed. The generation of high-throughput molecular data and bespoke bioinformatics capability to address these unique challenges offers an enormous opportunity for people living in the tropics. MAIN: In this review we discuss in depth solutions to challenges to populations living in tropical zones across three critical One Health areas: human health, biodiversity and food production. This review will examine how some of the challenges in the tropics can be addressed through the targeted application of advanced omics and bioinformatics and will discuss how local populations can embrace these technologies through strategic outreach and education ensuring the benefits of the One Health approach is fully realised through local engagement. Within the context of the One Health framework, we will demonstrate how genomic technologies can be utilised to improve the overall quality of life for half the world's population.

A-PoRM SIPLAS: Assessing The Post-Disaster Recovery Of Mangrove Forest In Siargao Island Protected Landscape And Seascape (SIPLAS) Area Using Sentinel-1 SAR Data

Abstract. Tropical cyclones and typhoons pose significant threats to coastal ecosystems, particularly mangrove forests. Assessing the extent of mangrove damage and monitoring recovery post-disaster is vital for effective conservation and management strategies. Space-based observations have become increasingly common in monitoring forest damage in tropical regions. However, the predominant methods for change detection rely on satellite optical imagery, which faces challenges in humid tropical zones. Technological advancements have led to the development of detection techniques utilizing synthetic aperture radar (SAR) to address cloud cover issues. The study specifically targets Siargao Island Protected Landscape and Seascape (SIPLAS), the largest contiguous forest in the Philippines, from destruction caused by Super typhoon Rai (Odette). The study utilized SAR time-series data, unsupervised log ratio change detection method and Cumulative Sum (CuSum) analysis via Google Earth Engine (GEE). Analysis of Sentinel-1 GRD images found VV polarization had the highest accuracy at 92% and an F-measure of 0.92. VH polarization had 87.5% accuracy and an F-measure of 0.87, while combining VV and VH and VV/VH achieved the same results of 80.5% overall accuracy with an F-measure of 0.82. With that, results indicated that 53% of mangroves in SIPLAS area were damaged, with 38.05% regenerating by 2022 and 56.75% by 2023, notably after September 16, 2022 detected from CuSum analysis using the VV polarization. These findings substantiate the robustness of the data and methodologies employed in monitoring mangrove resilience and supporting conservation initiatives within the SIPLAS area.

Hair coat of the water deer <I>Hydropotes inermis</I> (Cervidae, Artiodactyla) – a new species in the fauna of Russia

For the first time, the hair cover and hair microstructure of an adult male Hydropotes inermis from the Primorsky region of Russia were studied using light and scanning electron microscopy. The absence of abundant underfur, sparse wool and its weak layering are characteristic of this inhabitant of the temperate monsoon and tropical zones, which does not need an effective thermal protection.The alveolar and lattice medulla of the hair is similar to that of other deer, is well developed, and increases the heat-protective properties of the hair, since seasonal and daily fluctuations in temperature and humidity can be significant. The cuticle pattern is similar to that of deer tribes Alceini and Capreolini. The hair serves as reliable protection for the water deer from mechanical damage when moving through thickets of bushes and grasses along the banks of rivers and swamps in the biotopes that this deer inhabits, which is facilitated by the significant thickness and length of the hairs on the back, sides and thighs. The knotty nature of the hairs protects the deer’s skin from the sharp growths of aquatic and marsh plants.

Statistical Analysis of Atmospheric Delay Gradient and Rainfall Prediction in a Tropical Region

In recent years, precipitable water vapor has emerged as a key atmospheric parameter in weather prediction research. However, relying on only one parameter does not always accurately predict rainfall, as other atmospheric parameters also contribute to initiating rain events. In our previous study, we explored a methodology for rainfall forecasting based on the atmospheric delay gradient at an individual station in the tropical region. Commonly referred to as the atmospheric gradient, it accounts for the delay in GNSS signals due to changes in horizontal refractivity while propagating through the troposphere to the ground station. This paper discusses the spatial and temporal correlation of the gradient with precipitation occurring over a region. We have investigated different features, such as gradient magnitude, gradient convergence, and the flux of the atmospheric gradient, to propose potential nowcasting criteria for precipitation in the tropical climatic zone. The atmospheric gradient in the surrounding region orients toward the area of precipitation as the rain event approaches. This gradient gradually alters its orientation and converges toward the region of rainfall at the time of precipitation, introducing the concept of gradient convergence. This phenomenon results in an inward gradient flux at the time of the downpour, which presents a potential parameter for rainfall prediction over an area. We also proposed investigating area sizes of 4° × 4° or 8° × 8°, depending on the gradient feature, to establish a forecasting methodology for rainfall. The weather front in the tropical region begins to initiate 12 h before the actual time of occurrence and advances toward the area where it will have an impact from a more distant location. This article presents a detailed investigation of various features of the atmospheric gradient and its potential to nowcast rainfall for a region, as well as proposes the lead time for long-term weather predictions. Furthermore, a deep neural network has been employed to predict rainfall events for the next 6 h over an area in the tropical region.

Unraveling global species richness patterns of the Lysmatidae family: a multi-scale and multi-hypothesis ecological approach

While diversity gradients are well-explored in macroecology, factors shaping species richness at broad scales remain debated. We investigated the species richness of the decapod family Lysmatidae across 4 spatial scales: realm, province, ecoregion, and local (2° × 2° grid cells). We tested 4 ecological hypotheses: physiological stress (PSH), resource availability (RAH), habitat heterogeneity (HHH), and anthropogenic impact (AIH). Occurrence data (52 Lysmatidae species) and environmental variables (salinity, temperature, primary productivity, bathymetry, coral richness, anthropogenic impact index) were obtained from online databases and literature. Fifteen regression models, incorporating spatial filters, were tested to assess the hypotheses. The highest Lysmatidae species richness occurred in the Tropical Atlantic and Central Indo-Pacific realms. Richness varied with scale, with the highest values in the transition between the tropical and subtropical zones. Bathymetry was associated with Lysmatidae richness across all scales, especially at local and ecoregional scales, while coral richness was related to province and realm scales. HHH explained Lysmatidae richness patterns at the realm scale. Variables related to PSH and AIH were associated with richness at the ecoregion and province scales. Our study emphasized the importance of scale in biodiversity research, influencing richness patterns in Lysmatidae, and pointed to bathymetry, coral richness, and temperature range as the main drivers of richness. As this study showed a relationship between Lysmatidae richness, coral richness, and temperature at 3 spatial scales, this family may be susceptible to the effects of climate change, such as tropicalization of subtropical zones and defaunation of tropical ecosystems, including coral reefs.

Reconstructing Holocene centennial cooling events: synthesized temperature changes, chronology, and forcing in the Northern Hemisphere

Numerous studies, spanning experimental, instrumental, historical, and modeled approaches, have delved into understanding climate change across the Holocene era and millennial-scale occurrences. However, the chronology and causes of centennial-scale climate events during the Holocene remain controversial. In this study, we overviewed 10 of the best-resolved and most accurately dated records detailing climate change in the Northern Hemisphere (NH) over the Holocene, obtained from different proxies across different climatic zones, and constructed a stack of temperature changes in the NH. Based on the constructed stack, we identified and categorized 15 notable Holocene centennial cooling events (HCCEs) in the NH (period with temperature decreases). To test the chronological validity of the constructed HCCEs, we compared them with the most accurately dated and highly resolved climate records during the last 3 kyr, which have been extensively investigated by the scientific community. Based on the close alignment of the outlined HCCEs with temperature records, we suggest that other HCCEs also match centennial climate cooling events over the last 10 kyr. To understand the origins of the established HCCEs, we compared them with potential climate influencing factors: total solar irradiance (TSI), explosive volcanic activity, Atlantic meridional overturning circulation (AMOC)-limited slowdowns, Intertropical Convergence Zone (ITCZ) fluctuations, and El Niño/Southern Oscillation (ENSO variability. Early Holocene HCCE 5, terminated by a prominent 8.2-ka cold event, was likely driven by the superposition of the AMOC limited slowdown, TSI minimum, and volcanic activity. The Holocene Thermal Maximum (HTM) happened between HCCEs 5 and 4a and was interrupted by HCCE 4c and 4b, coeval, with a significant southward shift of the ITCZ, likely related to cooling in the tropical zone. However, the sequence of HCCEs 3b, 3a, and 2b (over 4.53–3.42 BP), accompanied by small changes in the TSI, was likely forced by an increase in ENSO variability, leading to remarkable changes in the tropical processes and a southward shift of the ITCZ, coeval with the collapse of the Chinese Neolithic cultures and onset of the Holocene Neoglacial. Subsequent HCCEs 2a–0a were likely forced by the TSI minimum combined with the influence of ENSO and volcanism over the last 2 ka.

Sexual activity and climatic adaptation assessment of West African Dwarf goats introduced into Algeria

This study aimed to highlight the effects of variations in age, seasons and climatic conditions on the reproductive activity of West African Dwarf Goats imported from tropical zones in Algeria, and to verify the degree of their adaptation to Mediterranean climatic conditions. For this purpose, testicular biometry and hormonal analysis (testosterone and LH levels) using the radioimmunological method were carried out monthly. In total, seven goats aged between 18 to 48+ months were surveyed during the period from September 2021 to March 2022. The results showed a considerable effect of age on testicular measurements. Bucks less than 18 months recorded the lowest average testicular length, width, thickness and volume, scrotal width and circumference, as levels of testosterone concentrations. All variables were strong correlated. Seasonal variations in the average testicular measurements and hormonal concentrations were observed, without affecting testicular activity. Apart from thenegative action of ambient temperature, no effects of relative humidity or atmospheric pressure were revealed. West African Dwarf Goats showed a good capacity to adapt to Mediterranean climatic conditions through their continuous testicular activity during the year.

The Effect of LED Lighting Durations on Growth, Yield and Quality of Mustard (Brassica juncea L.) under Greenhouse Condition

Light-emitting diodes (LEDs) show promise as a radiation source for intensive crop cultivation systems, especially for vegetables in the greenhouse. Regarding mustard greens, most studies have investigated the effects of LED lights at the seedling stage under chamber conditions for microgreens not addressed throughout their growing period up to harvest. Therefore, this study is focused to evaluate the effect of additional LED lighting time from 6 pm on the growth, yield and quality of mustard greens under a greenhouse in Kien Giang province as a typical tropical region. The experiment was arranged in a completely randomized design with 3 replications, from August 1st to September 18th, 2023. Four treatments: AL0, AL2, AL4 and AL6 correspond to lighting durations of 0, 2, 4 and 6 h of LED light, which includes a combination of 3 white lights: 1 pink light, 58 μmol·m−2·s−1 PPFD, and a Blue (18 %): Green (41 %): Red (41 %) ratio. Results showed that AL4 had the most significant positive impact on mustard plant growth, with higher dry and fresh weight, plant height, leaf width and length. However, AL6 inhibited most parameters except leaf number. Additionally, under AL4 conditions, mustard allocated more biomass to leaves, while those under AL6 conditions allocated more biomass to stems. In terms of quality, LED lighting duration negatively influenced protein content. For instance, AL0 showed the significantly greatest protein value (2.87 ± 0.08 g·kg−1) compared to others. Apart from AL0, AL6 had a considerably higher value of protein content (2.58 ± 0.2 g·kg−1) compared to AL2 (1.74 ± 0.04 g·kg−1) and AL4 (2.17 ± 0.07 g·kg−1). The additional durations of LED lighting influenced mature mustard greens’ morphology, physiology and quality, providing valuable scientific information for improving vegetable quality and quantity in tropical zones. HIGHLIGHTS 4 hours of additional LED light had the most significant positive impact on mustard plant growth, with higher dry and fresh weight, plant height, leaf width, and length. Additionally, leaf number increased under 6 hours of additional LED light. Under 4 hours of additional LED light, mustard allocated more biomass to leaves, while those under 6 hours of additional LED light allocated more biomass to stems. Lighting with LED resulted in a lower protein value, and different durations of LED lighting resulted in varying protein content values. GRAPHICAL ABSTRACT

Seagrass Biodiversity Under the Latest‐Generation Scenarios of Projected Climate Change

ABSTRACTAimThe potentially cascading consequences of climate changes on redistribution of habitat‐forming species, like seagrasses, remain a major research gap. Empirical demonstrations of local population changes are increasingly reported without a globally integrated predictive framework as a leading testable hypothesis. Therefore, here, we aimed to estimate changes in species richness, community composition, and areas of climatic refugia under future climate scenarios.LocationGlobal scale.Time PeriodPresent‐day conditions (from 2010 to 2020) and for three Shared Socioeconomic Pathway (SSP) scenarios of future climate change (from 2090 to 2100).Major Taxa StudiesSeagrasses (plantae).MethodsWe coupled seagrass occurrences with environmental predictors (temperature, salinity, nitrate, wave energy, and ice) in stacked species distribution modelling.ResultsModels estimated a present global extent of 917,169 km2 with high species richness in Temperate Australasia, Indo‐Pacific, and Temperate North Pacific. Future projections predicted widespread spatial redistribution, with Arctic expansions, losses in lower latitudes, and deeper vertical ranges, while globally maintaining the area extent occupied worldwide by seagrass species (only 5% of change). Species richness increased poleward under more drastic scenarios (SSP3‐7.0 and SSP5‐8.5), with losses in tropical zones (30oN to 30oS). Local climatic refugia are retained in all scenarios but decrease under higher emissions. Additionally, even where seagrass species remain, widespread community composition changes were predicted.Main ConclusionsOur findings serve as baselines to inform, anticipate, and mitigate cascading consequences of shifts in seagrass ecosystems that provide essential services for humanity.

Isolation and characterization of mung bean (Vigna radiata L.) rhizobia in Myanmar

AbstractWe collected soil samples from six major mung bean cropping regions in Myanmar: Sagaing, Mandalay, Nay Pyi Taw, and Magway in the tropical savanna climate zone and Bago and Yangon in the tropical monsoon climate zone. All fields grew mung bean for at least 5 years and had no history of rhizobial inoculation. Mung bean ‘Yezin-11’, a popular cultivar in Myanmar, was inoculated with soil suspensions. From the nodules formed on the roots, we isolated 55 rhizobial strains. Identification of the isolates revealed the dominant species of indigenous rhizobia in each region. We identified 53 Bradyrhizobium strains and 2 Ensifer strains. Bradyrhizobium yuanmingense was dominant in the tropical savanna zone and Bradyrhizobium sp. (B. liaoningense or B. diversitatis) and B. centrosematis were dominant in the tropical monsoon zone. Principal component analysis indicates that the dominance of B. yuanmingense in the tropical savanna zone might be due to high concentration of NO3-N and P2O5 in the soil. It also indicates that the dominance of B. centrosematis in the tropical monsoon zone might be caused by drastically low pH and high concentration of NH4 in the soil. Bradyrhizobium centrosematis YGN-M9, B. yuanmingense SGG-M3, and Bradyrhizobium sp. BGO-M5 significantly increased nodulation (nodule number and nodule dry weight), acetylene reduction activity, and shoot dry weight, respectively, relative to Ensifer terangae MDY-M6. Co-inoculation with these three strains increased nodulation significantly compared with single inoculation of BGO-M5. The characterization of mung bean rhizobia and selection of microbial inoculant candidates will be useful for the development of microbial inoculants in Myanmar.

Detecting Drought-Related Temporal Effects on Global Net Primary Productivity

Drought has extensive, far-reaching, and long-lasting asymmetric effects on vegetation growth worldwide in the context of global warming. However, to date, few scholars have attempted the systematic quantification of the temporal effects of drought on global vegetation across various vegetation types and diverse climate zones. Addressing this gap, we quantitatively investigated the effects of drought on global vegetation growth under various scenarios, considering lagged and cumulative effects as well as combined effects in the 1982–2018 period. Our investigation was based on long-term net primary productivity (NPP) and two multiple-timescale drought indices: the standardised precipitation index (SPI) and the standardised precipitation and evapotranspiration index (SPEI). Our main findings were the following: (1) SPI and SPEI exhibited lagged effects on 52.08% and 37.05% of global vegetation, leading to average time lags of 2.48 months and 1.76 months, respectively. The cumulative effects of SPI and SPEI were observed in 80.01% and 72.16% of global vegetated areas, respectively, being associated with relatively longer cumulative timescales of 5.60 months and 5.16 months, respectively. (2) Compared to the scenario excluding temporal effects, there were increases in the explanatory powers of SPI and SPEI for variations in vegetation NPP based on the lagged, cumulative, and combined effects of drought: SPI increased by 0.82%, 6.65%, and 6.92%, respectively, whereas SPEI increased by 0.67%, 5.73%, and 6.07%, respectively. The cumulative effects of drought on global vegetation NPP were stronger than the lagged effects in approximately two-thirds (64.95% and 63.52% for SPI and SPEI, respectively) of global vegetated areas. (3) The effects of drought on vegetation NPP varied according to climate zones and vegetation types. Interestingly, vegetation in arid zones was the most sensitive and resilient to drought, as indicated by its rapid response to drought and the longest cumulative timescales. The vegetation NPP in tropical and temperate zones exhibited a relatively stronger response to drought than that in cold and polar zones. The strongest correlation of vegetation NPP with drought occurred in shrubland areas, followed by grassland, cropland, forest, and tundra areas. Moreover, for each vegetation type, the correlations between vegetation NPP and drought differed significantly among most climate zones. (4) The vegetation NPP in warming-induced drought regions displayed a higher correlation to drought than that in non-warming-induced drought regions, with shorter lagged and longer cumulative timescales. Our findings highlight the heterogeneity of the lagged, cumulative, and combined effects of drought across various climate zones and vegetation types; this could enhance our understanding of the coupling relationship between drought and global vegetation.

Satellites Reveal Global Migration Patterns of Natural Mountain Treelines during Periods of Rapid Warming

Profound global transformations in the Anthropocene epoch are hastening shifts in species ranges, with natural mountain treeline migration playing a crucial role in this overarching species movement. The varied reactions of mountain treelines to climatic conditions across diverse climatic zones, when compounded by local disturbances, result in distinct migration patterns. Usually, warming encourages mountain treelines to migrate to higher elevations. Nevertheless, in a period of rapid warming, it remains unclear whether the natural mountain treeline in global thermal climatic zones and subclimatic zones has expedited its upward movement. Here, we employed remote sensing observations and the random forest algorithm to investigate the natural treeline dynamics across 24 major mountain ranges worldwide amidst a period of rapid warming (1990–2020). Our research shows substantial disparities in the migration patterns of natural mountain treelines across the global thermal zone. The natural mountain treeline in tropical and subtropical zones descends by an average of 1.1 and 0.8 m per year, respectively. Only 18.8 and 35.5% of the natural mountain treelines in these regions had undergone upward migration, respectively. The average migration rates of natural mountain treelines in temperate and boreal zones were 0.7 m per year. Correspondingly, 47 and 33.2% of the natural mountain treelines in these zones had already shifted to higher elevations. The highest average migration rate of natural mountain treelines occurs in temperate continental climates (1.7 m per year). The loss or degradation of alpine species habitats, a direct consequence of the upward movement of the treeline, highlights the necessity for increased monitoring and protection of alpine species in temperate and boreal zones in the future.

Critical needs to close monitoring gaps in pan-tropical wetland CH4 emissions

Abstract Global wetlands are the largest and most uncertain natural source of atmospheric methane (CH4). The FLUXNET-CH4 synthesis initiative has established a global network of flux tower infrastructure, offering valuable data products and fostering a dedicated community for the measurement and analysis of methane flux data. Existing studies using the FLUXNET-CH4 Community Product v1.0 have provided invaluable insights into the drivers of ecosystem-to-regional spatial patterns and daily-to-decadal temporal dynamics in temperate, boreal, and Arctic climate regions. However, as the wetland CH4 monitoring network grows, there is a critical knowledge gap about where new monitoring infrastructure ought to be located to improve understanding of the global wetland CH4 budget. Here we address this gap with a spatial representativeness analysis at existing and hypothetical observation sites, using 16 process-based wetland biogeochemistry models and machine learning. We find that, in addition to eddy covariance monitoring sites, existing chamber sites are important complements, especially over high latitudes and the tropics. Furthermore, expanding the current monitoring network for wetland CH4 emissions should prioritize, first, tropical and second, sub-tropical semi-arid wetland regions. Considering those new hypothetical wetland sites from tropical and semi-arid climate zones could significantly improve global estimates of wetland CH4 emissions and reduce bias by 79% (from 76 to 16 TgCH4 y−1), compared with using solely existing monitoring networks. Our study thus demonstrates an approach for long-term strategic expansion of flux observations.

Impacts of aquaculture practices on the sustainability of social-ecological systems in coastal zones of the Mekong Delta

Coastal and deltaic regions face increasing natural and human-induced hazards, such as cyclones, storm surges, erosion, and saline intrusion, exacerbated by climate change. In tropical zones, mangrove ecosystems provide vital protection against these threats, yet the conversion of mangroves to shrimp aquaculture undermines these benefits, even in protected areas.The Mekong Delta in Vietnam, historically rich in biodiversity and diverse habitats like mangroves and mudflats, has seen local communities thrive. However, rising global market demands have led to more intensive aquaculture models, posing new risks.This research examines the impact of shrimp farming models, from extensive to hyper-intensive, under multiple natural hazards and transformative processes like land conversion and mangrove restoration. Using risk assessment tools and data from local community interviews and focus groups, we present a model showcasing the influence of aquaculture on socio-ecological systems.Key findings reveal the interplay between livelihoods and landscape conversion, highlighting the risks and benefits of various shrimp farming models. The study stresses the need for stakeholder collaboration and improved wastewater treatment to enhance sustainability and environmental health in the Mekong Delta.

Clay mineralogy in mylonite weathering products from Njimom (west Cameroon): origin and terracotta suitability

This study investigated the mineralogical assemblage of weathering products developed on mylonite rocks in west Cameroon. Smectite and vermiculite occurrence was studied, particularly to emphasize its origin and the potential of the samples in terracotta production. Samples characteristics were determined through X-Ray Diffraction (XRD) and X-ray Fluorescence (XRF) methods. Weathering products were observed along road trenches of 450 m long and 50 m height on a syenitic basement rock intruded by magmatic rock veins. Clay minerals are mainly composed of kaolinite and illite. 2:1 swelling clay minerals (vermiculite, montmorillonite) occur in some samples mainly originated from the contact between weathering materials and quartzo feldspatic bands. The main oxides are SiO2 (46–72%), Al2O3 (16–31%), Fe2O3 (2–16%) and K2O (0.1–6%). Vermiculite may be formed by fluid-mineral interactions during alteration of the chlorite in the plasmic microsystems of the soil. Structural changes in the upper part of the saprolite leading to the transformation of vermiculite into smectite under supergene alteration control, which predominates in humid tropical zones. Heavy rainfall leads to the formation of kaolinite at the expense of 2:1 clay minerals. Empirical classification revealed that the studied weathering products can be used to produce common bricks.

Meta-analysis: Global patterns and drivers of denitrification, anammox and DNRA rates in wetland and marine ecosystems

Nitrogen cycling is one of the most important biogeochemical processes on Earth, and denitrification, anammox and DNRA processes are important nitrogen cycling processes in estuarine ecosystems. However, due to the large input of anthropogenic nitrogen sources, a large number of environmental problems have now occurred in the estuary. But the global patterns and controlling factors of denitrification, anammox and DNRA rates in wetland marine ecosystems are not yet known. We reached our conclusions through a global synthesis of 546 observation sites from 78 peer-reviewed papers: The three rates were generally higher in areas near wetlands than in coastal areas. The rate of denitrification was highest in the subtropical region the seasonal variability was not significant; and TOC was the main factor controlling denitrification. The rate of anammox was significantly higher in the subtropical region than in the tropical and boreal zones, and the seasonal variability was significant; and at the same time, TN was the main driver of the anammox rate of the wetland ocean. DNRA rates were significantly higher in the tropics than in the subtropics and temperate zones; and the main driver of DNRA rates was temperature. Nitrogen cycle functional genes also had an indirect effect on their rates. With NH4 + -N significantly affecting nirK abundance and TN significantly affecting the gene abundance of nirS; TOC and TN had a greater effect on hzo abundance, which indirectly affected anammox rates; for DNRA, C/N significantly affects the gene abundance of nrfA, which indirectly affects the DNRA rate. Therefore, the findings of this study indicate that physicochemical indicators about N and climatic characteristics have a profound effect on the nitrogen cycling process, which provides a good feedback for studying the role of denitrification and provides a positive impact on global climate and environmental governance.

Occurrence and Distribution Patterns of Antibiotic-resistant Bacterial Genes in Agricultural Lands of Japan, Indonesia and the Philippines

Aim: The spread of Antibiotic-Resistant Bacteria (ARB) worldwide leads to difficult and prolonged treatment of diseases and causes significant damage to human health and the environment. In this study, the distribution of resistance genes was investigated in terms of country, plant species, and with/without manure. Methodology: Fifty-five soil DNA libraries from Japan, the Philippines and Indonesia were amplified by PCR, and electrophoresis was used to detect target bands of antibiotic resistance genes (ARGs), which included three types of sulfonamide resistance, Sul1, Sul2, and Sul3; eight types of tetracycline resistance, TetM, TetO, TetS, TetW, TetC, TetA, TetB, and TetL; blaTEM for beta-lactam resistance; ermB for macrolide resistance; and qnrA for quinolone resistance, intl1 as integrons. Results: The most characteristic results were obtained for plant species, and the difference between orchards and fields was found to affect the resistance genes. The distribution of genes was bimodal between Japan, which belongs to the temperate zone, and the Philippines and Indonesia, which belong to the tropical zone, and the differences in drug resistance genes were found to be due to differences in biome. The detection rate increased in soils with and without manure, but there were no significant differences in resistance genes other than ermB.