Sampling Season Research Articles

Fermented foods affect the seasonal stability of gut bacteria in an Indian rural population

The effect of fermented foods on healthy human gut microbiota structure and function, particularly its seasonal preference and frequent long-term consumption, has been largely uncharacterised. Here, we assess the gut microbiota and metabolite composition of 78 healthy Indian agrarian individuals who differ in the intake of fermented milk and soybean products by seasonal sampling during hot-humid summer, autumn and dry winter. Here we show that, seasonal shifts between the Prevotella- and Bifidobacterium/Ruminococcus-driven community types, or ecological states, and associated fatty acid derivatives, with a bimodal change in Bacteroidota community structure during summer, particularly in fermented milk consumers. Our results associate long-term fermented food consumption with reduced gut microbiota diversity and bacterial load. We identify taxonomic groups that drive the seasonal fluctuation and associated shifts between the two ecological states in gut microbiota. This understanding may pave the way towards developing strategies to sustain a healthy and resilient gut microbiota through dietary interventions.

Response of Hard-Bottom Macro-Zoobenthos to the Transition of a Mediterranean Mariculture Fish Plant (Mar Grande of Taranto, Ionian Sea) into an Integrated Multi-Trophic Aquaculture (IMTA) System

: This study investigates the effects on hard-bottom macro-zoobenthic communities of converting a mariculture plant into an Integrated Multi-Trophic Aquaculture (IMTA) system. This study was conducted from 2018 to 2021 in the semi-enclosed Mar Grande basin of Taranto (northern Ionian Sea), on a facility located 600 m off the coastline, with a production capacity of 100 tons per year of seabass (Dicentrarchus labrax) and seabream (Sparus aurata). The results from seasonal sampling performed in a treatment site, where bioremediators (filter-feeding invertebrates such as sponges, polychaetes, mussels, and macroalgae) were deployed, and a control site without bioremediators were compared. Before the IMTA installation, the hard substrates under the cages were sparsely inhabited, with significant sediment coverage. By 2021, the treatment site exhibited revitalized and more diverse macro-zoobenthic communities, with species richness increasing from 83 taxa in 2018 to 104 taxa, including notable growth in sponges, annelids, mollusks, and bryozoans. In contrast, the control site showed no substantial changes in biodiversity over the same period. Biodiversity indices, including Shannon and Margalef indices, improved significantly at the treatment site, particularly during summer months, highlighting a more resilient and balanced benthic environment. Taxonomic distinctness (delta+) and multivariate analyses (PERMANOVA, PCO) confirmed significant spatial and temporal shifts in community structure at the treatment site, driven by IMTA implementation. SIMPER analysis identified key taxa contributing to these changes, which played a pivotal role in structuring the community. The emergence of filter feeders, predators, and omnivores at the treatment site suggests enhanced nutrient cycling and trophic complexity, while the decline in opportunistic species further supports improved environmental conditions. These findings demonstrate the potential of IMTA to promote recovery and sustainable mariculture practices, also offering a comprehensive understanding of its positive effects on hard-bottom benthic community dynamics.

Serum free 25(OH)D concentrations and cardiovascular disease, heart failure, kidney function decline, and fracture: the health, aging, and body composition study

Abstract Vitamin D deficiency is common across the world. However, the standard clinical biomarker for vitamin D, 25-hydroxyvitamin D, may be a poor marker of vitamin D status, as most of circulating vitamin D is protein bound and not bioavailable. Free (unbound) vitamin D may therefore be a better marker of vitamin D status. We evaluated the relationship of free vitamin D with incident cardiovascular disease (CVD), heart failure (HF), kidney function decline (KFD) and fracture, among 786 participants in the Health Aging and body composition study. We used sequential models to assess hazard ratios (HR) of each outcome that adjusted for age, sex, race, season of blood sampling, and study site, kidney function, serum calcium and phosphate, fibroblast growth factor 23, parathyroid hormone, body mass index, and vitamin D supplementation. The mean age of the 786 participants was 75 ± 3 years, 53% were women, 40% were Black. The median free vitamin D concentration was 5.3 (interquartile range 4.1-6.7) pg/ml. There were 157 cases of incident CVD, 123 cases of incident HF, 382 cases of incident KFD, and 178 fractures over 11 years of follow up. In fully adjusted models, a two-fold greater free vitamin D was associated with lower risk of incident HF [HR 0.75, 95%CI(0.58-0.96)] and greater risk kidney function decline[1.25(1.03-1.52)]. We found no association between free vitamin D and incident CVD or fracture. We did not find evidence that free vitamin D was a superior marker of clinical outcomes compared to total 25-hydroxyvitamin D alone. Further studies are needed to elucidate the relationship of free vitamin D with clinical outcomes.

Benthic marine invertebrate herbivores diversify their algal diets in winter

AbstractChanges in the seasonal environment substantially influence organisms. Understanding how species respond to such changes, such as in their feeding interactions and physiology, is key to predicting their resilience to both seasonal and longer term climate changes. The Sitka Sound in Southeast Alaska, USA, is an attractive natural laboratory for studying change, as the marine environment experiences substantial seasonal fluctuations in parameters such as temperature, pH, and productivity between summer and winter. By sampling a suite of dominant macrophyte algae and their benthic herbivores in winter (January) and summer (July) 2019, we investigated how producers and their primary consumers may respond to seasonal change inferred through fatty acid trophic markers. We used a fatty acid logratio selection and analysis approach to ask the following: (1) Do fatty acid biomarkers for algae differ between seasons? (2) Do the same fatty acid biomarkers differ between seasons when applied to herbivores, with herbivore fatty acids tracking the presumed trophic resources? (3) Do fatty acid biomarkers for herbivores differ between seasons, when considered independently from algae? Comparing logratio sets selected each for the algae and the herbivore fatty acids, we found that algae fatty acids were different between our sampling seasons, but the algae‐selected fatty acid logratios did not clearly separate most herbivores by season. In contrast, the herbivore‐selected logratios strongly distinguished herbivore species between the January and June samplings. Further, dispersions of fatty acid logratios were greater within herbivore species in the winter than in the summer, potentially due to the utilization of more diverse resources when preferred algae are less abundant. In total, results suggest that herbivores are not simply tracking the seasonal fatty acid changes in the dominant algae as trophic resources; instead, herbivore fatty acid seasonal changes may occur largely through some other nonexclusive mechanisms, such as omnivory, reductions or shifts in dietary composition, and/or endogenous physiological responses. Thus, the benthic herbivores in our study appear not to be locked into their diets when faced with seasonal change and may use a range of strategies, including diet diversification, to cope with environmental variation.

Ovine Toxoplasmosis Sero-Status, Risk Factors Analysis, and Estimation of Haematological and Serum Biochemical Alterations.

Toxoplasmosis is a significant food-borne protozoal disease in humans and animals. The study aimed to find out Toxoplasma seropositivity in sheep, estimate epidemiological risk factors and assess haemato-biochemical parameter changes. Blood samples were collected from 276 indigenous sheep in five districts surrounding Sulaymaniyah Province in the northern region of Iraq. Toxoplasmosis was determined by detecting anti-Toxoplasma antibodies by ELISA. The impact of various risk factors on seropositivity was evaluated. Haematological and serum biochemical changes from naturally infected sheep were analysed using commercial kits. The overall seroprevalence of Toxoplasma antibodies among the studied population was 41.67%. Sharazoor district had a higher prevalence rate of 46.15% than Bakrajo, with the lowest frequency rate of 38.18%. Ewes with an abortion history had a higher risk for seropositivity of about 47.4% (OR=1.4, 95% CI: 0.9-1.6). Sampling season and herd size are other risk factors, with higher seropositivity at 42.5% (OR=1.1, 95% CI: 0.8-1.4) during the dry season and among small flocks ≤100 animals/farm at 43.6% (OR=1.1, 95% CI: 0.7-1.4). Toxoplasma prevalence was correlated with animals' ages; a higher seropositivity of 43.3% was found among older sheep (OR=0.8, 95% CI: 0.6-1.2). Seropositive sheep had significantly higher total leukocyte, lymphocyte and granulocyte counts but significantly lower haemoglobin, haematocrit and total erythrocyte counts. The serum levels of total protein and albumin were significantly reduced, with increased blood urea nitrogen and creatinine concentrations. Also, AST enzyme activity represents a higher value in positive sheep with toxoplasmosis. Toxoplasma infection among the ovine population is common. Its impact on livestock productivity should not be neglected. A potential risk for humans through infected sheep could be a hazardous source for public health.

Impacts of early and repeated fires on microbial activities in the wooded savannahs of Burkina Faso

Bush fires which effects depend on their intensity as well as their season of occurrence are considered as a major disturbance of savanna ecosystems. The objectives of this research were to understand the changes induced on the properties of the soil by repeated early fires on microbial activities. The study was conducted on a factorial design installed on two (02) sites, namely the classified forest of Dindéresso located in the West (firsts fires were applied in 2010) and that of Tiogo located in the Center West (first fire were applied since 1992) of the country. Measurements have been carried out before, after the passage of the fire and during the rainy season on soils. The results obtained showed that the period during which the measurements were taken played a role in the microbial dynamics, thus showing the highest rates in the rainy season for the control (3.02 C g.m-2) and the burnt plots (3.63 C g.m-2) after fire. Microbial nitrogen is the element that varied considerably, going from 1.60 for the control to 1.74 N g.m-2 for the burnt plots for the Dindéresso site. Concerning Tiogo, the microbial biomass is higher on the burned plots (6.04 C g.m-2) and (6.01 C g.m-2) for the control in rainy season sampling.

Artisanal and small-scale limestone mining affects soil parameters in Sohra (Meghalaya), India.

In this study, we assessed the changes in the physical and chemical characteristics of the soil samples collected from the artisanal and small-scale limestone mining site in Sohra (Cherrapunjee), Meghalaya, by comparing them with the non-mining site. Eleven distinct soil parameters, namely pH, electrical conductivity (EC), texture (ST), moisture content (MC), bulk density (BD), total porosity (TP), water holding capacity (WHC), organic carbon (OC), total nitrogen (TN), available phosphorus (AP), and exchangeable potassium (EK), were evaluated seasonally (winter, pre-monsoon, and post-monsoon) for 2years. The results showed that limestone mining has significantly affected the soil quality. The effect is evident by the substantial increases in EC values, sand content, and alkaline soils coupled with noticeably low concentrations of OC and TN. In addition, prominent changes were perceived in the soil MC and EK content, as well as in WHC, BD, and TP percent. Results from ANOVA revealed significant differences (p < 0.05) in mean values at different sampling seasons and sites. The multivariate statistical analysis results showed that the computed correlation coefficient (r) matrix data ranged from - 1.00 to 0.974. A strong positive correlation was highest between OC and TN (0.974), followed by OC with EK (0.828). Principal component (PC) analysis revealed two major components, PC 1 and PC 2, having eigenvalues of 6.276 and 1.747, respectively. Cumulatively, these two components explained 80.23% of the total variance. The loading factor in PC 1 is high and is attributed to OC (.974), TN (.970), and EK (.903). However, in PC 2, the loading factor is positively pooled by MC (0.894) and TP (0.765). The present study concludes that artisanal and small-scale limestone mining altered the soil's physical and chemical properties, and these changes are likely to have a subsequent deteriorating impact on the area's biodiversity, landscape, and natural ecosystem. Therefore, to minimize the impact and ensure sustainable soil management in the area, approaches for effective mitigation and remediation measures, including formulating steps for the conservation and enhancement of the soil's environmental quality, are recommended.

Fine sediment-associated contaminants in gravel bed rivers: Evaluating storage times and turnover using fallout radionuclides (FRNs).

Excess fine sediment supply and its associated contaminants can have detrimental effects on water quality and river ecology with sediment deposition on, and subsequent infiltration in, streambeds impacting riverine habitats. Fallout radionuclides (FRNs) are used as tracers in aquatic systems, and the 7Be/210Pbex ratio is a useful indicator for sediment residence/storage time. Suspended and submerged mid-channel bar sediments were collected during five surveys within a 5km reach of a typical temperate lowland agricultural river system. Solids were analysed by gamma (7Be and 210Pbex) and inductively coupled plasma (ICP, trace metals and phosphorus) spectrometry, and analysed for total nitrogen and organic carbon, to assess sediment dynamics and associated contaminant and nutrient storage. Significant spatial and temporal variation in 7Be/210Pbex activity ratios was observed, indicating changes in sediment sources closely related to contaminant inputs from legacy mining and agriculture. Storage times and the proportion of recently deposited sediment (RDS) varied between sampling sites and seasons in response to local channel characteristics and floods, which also influenced particulate contaminant distributions. This study demonstrates that FRN technology offers improved understanding of fine sediment and contaminant storage and turnover in river channel systems, which is vital to aid sediment management, river restoration and to tackle the global challenge of siltation and associated pollution in riverine habitats.

Study of factors associated with the false-positive rate of second-trimester serological screening in 632,825 cases in Sichuan based on propensity score matching

To retrospectively analyze the results of second-trimester serological prenatal screening and explore the factors which may influence the false-positive rate (FPR). From January 2013 to December 2022, false-positive samples with follow-up outcomes from 632,825 second-trimester serological prenatal screening samples tested at Sichuan Provincial Maternity and Child Health Care Hospital were selected as the study group, while true-negative samples were 1 : 1 matched as the control group by propensity-score matching (PSM). Univariate and binary logistic regression models were used to analyze the influencing factors. This study was approved by the Medical Ethic Committee of Sichuan Provincial Maternity and Child Health Care Hospital (Ethic No. 20240607-270). The study and control groups were each matched with 305,998 cases. Univariate analysis showed that sampling season, the difference between ultrasound and gestational weeks calculated by last menstrual period (LMP), monthly median multiple of the median (mMoM) of alpha-fetoprotein (AFP), and monthly mMoM of free β -human chorionic gonadotropin (free β -hCG) were significantly different between the two groups (P < 0.05). Binary logistic regression analysis showed that Winter (OR = 0.938; 95%CI: 0.893 ~ 0.985), monthly AFP mMoM ≥ 1.11 (OR = 0.846; 95%CI: 0.761 ~ 0.941), monthly free β -hCG mMoM ≥ 0.89 (OR = 0.827; 95%CI: 0.737 ~ 0.929) are protective factors for FPR increase, whilst Spring (OR = 1.124; 95%CI: 1.072 ~ 1.179), Summer (OR = 1.121; 95%CI: 1.062 ~ 1.183), the difference between ultrasound and gestational weeks calculated by LMP of 8 ~ 14 days (OR = 1.319; 95%CI: 1.241 ~ 1.402), < 14 days (OR = 1.689; 95%CI: 1.542 ~ 1.850), monthly AFP mMoM of 0.90 ~ 0.94 (OR = 1.088; 95%CI: 1.046 ~ 1.131), and monthly free β -hCG mMoM of 1.05 ~ 1.10 (OR = 1.046; 95%CI: 1.000 ~ 1.094), ≥ 1.11 (OR = 1.062; 95%CI: 1.002 ~ 1.126) are risk factors for FPR increase. Sampling season, difference between ultrasound and gestational weeks by LMP, monthly AFP mMoM, and monthly free β -hCG mMoM are risk factors for FPR during serological prenatal screening. Screening laboratories should look for the cause of abnormal FPR through such factors and adjust them accordingly.

Denitrifying microbial genes quantification attests inference for potential N2O emissions in sugarcane soils by enzymatic bioanalysis

This study evaluated the relationships and sensitivity of denitrifying microbial gene abundance, as well as the activities of soil enzymes β-glucosidase (GLU) and arylsulfatase (ARYL), to assess the quality of sugarcane soils managed with vinasse (V), filter cake (FC), and mineral fertilizer (MF). Composite soil samples were collected using a systematic sampling approach that included two soil classes (Ferralsol and Acrisol), two textures (clayey and sandy), three management systems (V, V+FC, and MF), two sampling seasons (rainy and dry), and three replicates, totaling 72 samples. Analysis of soil organic carbon (SOC), and macro- and micronutrients differentiated the Ferralsol and Acrisol samples into distinct groups based on agricultural management (Global R = 0.554) and showed some overlap based on soil texture (Global R = 0.369). The number of nirK, nirS, and nosZ I gene copies per gram of soil, determined by Real-Time Quantitative PCR (qPCR) based on genomic DNA isolated from the 72 soil samples, was higher in the rainy season compared to the dry season (P&amp;lt;0.05). None of the genes evaluated revealed a consistent response to different sugarcane soil managements, showing specific response patterns for each soil class and texture. In the Ferralsol, the activities of GLU and ARYL increased in the following order: V &amp;lt; MF &amp;lt; V+FC, regardless of soil texture (sandy or clayey) and sampling season. The average activity of the two enzymes in both V+FC and MF treatments was 1.8 times higher in sandy soil and 3.9 times higher in clayey soil compared to soil managed with vinasse. In the Acrisol, no significant differences among the treatments were observed. Statistical analyses revealed negative correlations (P&amp;lt;0.05) between the number of copies of the nirK and nosZ I genes and GLU and ARYL activities in the soil during both seasonal periods analyzed. The number of copies of these two microbial genes was also negatively correlated with the soil organic matter in the rainy season. Thus, the indications of sugarcane soil quality based on enzymatic analyses were corroborated by the lower abundance of genes associated with denitrification process. The findings of this study open the possibilities to infer about the potential for N2O emission from these sugarcane soils based on GLU and ARYL activities.

High-Severity Wildfires Alter Ant (Hymenoptera: Formicidae) Foraging Assemblage Structure in Montane Coniferous Forests and Grasslands in the Jemez Mountains, New Mexico, USA

High-severity wildfires create heterogeneous patterns of vegetation across burned landscapes. While these spatial patterns are well-documented, less is known about the short- and long-term effects of large-scale high-severity wildfires on insect community assemblages and dynamics. Ants are bottom-up indicators of ecosystem health and function that are sensitive to disturbance and fill a variety of roles in their ecosystems, including altering soil chemistry, dispersing seeds, and serving as a key food resource for many species, including the federally endangered Jemez Mountain salamander (Plethodon neomexicanus). We examined the post-fire effects of the 2011 Las Conchas Wildfire on ant communities in the Valles Caldera National Preserve (Sandoval County, New Mexico, USA). We collected ants via pitfall traps in replicated burned and unburned sites across three habitats: ponderosa pine forests, mixed-conifer forests, and montane grassland. We analyzed trends in species richness, abundance, recruitment, loss, turnover, and composition over five sequential years of post-fire succession (2011–2015). Ant foraging assemblage was influenced by burn presence, season of sampling, and macrohabitat. We also found strong seasonal trends and decreases over time since fire in ant species richness and ant abundance. However, habitat and seasonal effects may be a stronger predictor of ant species richness than the presence of fire or post-fire successional patterns.

Impact of water deficit on the anatomical structure of more productive and less productive cashew trees (Anacardium occidentale L.) in Côte d’Ivoire

This study aimed to understand the mechanism of resilience of the anatomical tissues of organs of the cashew tree in water deficit in the different climatic zones of Côte d'Ivoire. To achieve this, samples of leaves and roots were taken from 55 cashew trees considered high producers (APHP) and 164 neighboring less productive trees (non-APHP) during the dry and rainy seasons. The technique of double staining with green-carmino made it possible to obtain anatomical sections of transversely cut samples under an optical microscope. The thicknesses and surface areas of the sections were measured using Image J software. The thickness of the leaves parenchymas of APHP trees did not show any variation according to the season while the stomatal density increased during the dry season. The thickness of the leaves cortical and medullary parenchymas of non-APHP trees did not show any variation according to the season too but the non-APHPs’ palisade parenchyma thickness increased while their lacunar parenchyma thickness decreased from 37 ± 1.5 mm to 36 ± 3.6 mm during the dry season. The thickness of leaves’ both sides epidermis increased while the thickness of xylem bundles decreased during the dry season to both APHP and non-APHP trees. The number of the roots’ xylem vessels of APHP trees increased from 11 to 27 vessels/mm2 while those of non-APHP trees increased from 15 to 41 vessels/mm2 during the rainy season. The surface area of the midrib medullary parenchyma of APHP trees increased from 4300 ± 837 mm2 to 5800 ± 412 mm2 while those of non-APHP trees increased from 3400 ± 809 mm2 to 5200 ± 993 mm2 during the dry season. The thicknesses of the tissues of APHPs remained greater than those of non-APHPs, regardless of the sampling season.

Identification of Soil Quality Factors and Indicators in Mediterranean Agro-Ecosystems

Soil quality offers a holistic approach for understanding the relationships between soil’s biological, chemical, and physical properties, which is crucial for sustainable land use and the management of non-renewable soil resources. This study evaluates the impact of land use on a set of 23 soil quality indicators (SQIs) across 5 land uses of the Mediterranean agro-ecosystems: forest, olive groves, wheat fields, a corn/wheat crop rotation system, and pasture. Seasonal soil sampling was carried out over two consecutive years in three conventionally managed fields representing each land use type. For each sampling, physicals SQIs (soil moisture, porosity-Vp-, bulck density-BD-, water holding capacity-WHC-, clay, silt, sand), chemical SQIs (organic carbon-Corg-, total Nitrogen-TN-, C/N, PH, electrical conductivity-EC-, ammonium-NH4-N-, nitrate-NO3-N- and available nitrogen-Nmin-), and biological SQIs (soil microbial biomass C-Cmic- and N-Nmic-, Cmic/Nmic, Cmic/Corg, Nmic/TN, active carbon—Cact-, Cact/Corg) were evaluated. Through multivariate analysis, five key soil quality factors—organic matter, microbial biomass, nutrients, C/N ratio, and compaction—were identified as indicators of soil quality changes due to land use, explaining 82.9% of the total variability in the data. Discriminant analysis identified organic matter and the C/N factors as particularly sensitive indicators of soil quality changes, reflecting the quantity and quality of soil organic matter, incorporating 87.8% of the SQIs information resulting from the 23 indicators. ΤΝ, accounting for 84% of the information on the organic matter factor, emerges as a key indicator for predicting significant changes in soil quality due to land use or management practices. The TN and C/N proposed indicators offer a simplified yet effective means of assessing soil resource sustainability in the Mediterranean agroecosystems, providing practical tools for monitoring and managing soil quality.

Comparative feeding habits of the invasive non-indigenous devil firefish Pterois miles and the indigenous scorpionfishes Scorpaena porcus, Scorpaena scrofa, and Scorpaena notata on the southwest coast of Türkiye, eastern Mediterranean

The feeding habits of the invasive alien devil firefish (Pterois miles) and the indigenous scorpaenids Scorpaena porcus, Scorpaena scrofa, and Scorpaena notata in the eastern Mediterranean Sea were investigated based on stomach content analysis. Furthermore, we examined whether these confamiliar species feed upon similar prey. Specimens were captured by professional fishers using trammel nets on the southwestern coast of Türkiye in the winter and summer of 2021. A total of 608 stomachs (286 P. miles, 112 S. porcus, 136 S. scrofa, and 74 S. notata) were investigated. The results demonstrate that the diet of P. miles included a total of 45 taxa, with 33 identified at the species level (27 indigenous, 6 non-indigenous), while those of the three congeneric scorpaenids included a total of 46 taxa and 37 identified species (30 indigenous, 7 non-indigenous). For P. miles, the highest index of relative importance (%IRI) values were determined for fish in both seasons (83.44% in winter, 93.82% in summer), with the damselfish Chromis chromis being the most preferred species. S. scrofa fed mainly on fish in winter and cephalopods in summer, whereas the diets of S. porcus and S. notata included mainly crustaceans in both seasons. In winter, P. miles exhibited a higher percentage of empty stomachs, demonstrating a significant difference in the vacuity index in different sampling seasons, while other scorpaenids did not exhibit statistically significant differences. This study also provides the northernmost record of the non-indigenous crab species Gonioinfradens giardi and the second record of the squat lobster Dactylonida curvimana in Türkiye. It also provides new reports of rarely observed fish species for the eastern Mediterranean, including Bellottia apoda and Odondebuenia balearica.

Planting date in South Kivu, eastern DR Congo: A real challenge for the sustainable management of Spodoptera frugiperda (Lepidoptera: Noctuidae) by smallholder farmers.

There is growing research interest in the fall armyworm (FAW) Spodoptera frugiperda, a polyphagous insect that is a major pest of maize crops worldwide. We investigated the relationship between planting date of maize and FAW infestation in South Kivu, eastern Democratic Republic of Congo, in two sampling seasons (September to October 2020 and February to March 2021). Five planting dates were considered for 45 fields in each season. The incidence, severity of attack and larval density of FAW were assessed at the 8-leaf stage (V8) of maize development in monoculture and intercropping systems. Planting period, classified as late or early, had a strong influence on FAW larval density, incidence and severity. The results showed that the late planting period (mainly on 30 October in season-1 and 30 March in season-2) had the highest larval density, incidence and severity of attack compared to the early planting period (15 September in season-1 and 01 Mars in season-2). During the season-1, five larval stages were found in the same field, whereas all larval stages were present in season-2, regardless of planting period. High densities of L4, L5 and L6 larvae were much more associated with late planting and incidence appeared to be highest when these larvae were present. The presence of L2 and L3 larval stages was observed in maize cropping systems intercropped with soybean and peanuts, while maize in monoculture and intercropped with cassava and beans was colonized by L4, L5 and L6 larvae. This study highlights the existence of different maize planting dates in South Kivu and demonstrates that late plantings have significant FAW infestations compared to early plantings. It provides a basis for developing climate-smart integrated pest management.

Microhabitat conditions and habitat configuration influence juvenile salmonid use of off-channel features in the Cedar River, Washington

Abstract Objective Off-channel habitats are crucial for freshwater rearing of juvenile Pacific salmon Oncorhynchus spp., but many of these river floodplain habitats have been lost to human development. While there is a clear need to restore and reconnect off-channel habitats to help recover imperiled salmonid populations, uncertainty exists regarding which characteristics to prioritize when constructing off-channel habitats to maximize the salmonid rearing capacity of these features. To address this uncertainty, we quantified the relative influence of microhabitat conditions and habitat configuration on juvenile salmonid densities within off-channel features of the Cedar River (Washington State). Methods We measured microhabitat conditions (water velocity, water depth, cover, and large wood density), habitat configuration (habitat type, distance from the main-stem river, and feature width), and salmonid densities at randomly selected sample units within side channels and backwaters. Result Water velocity and depth were strongly associated with subyearling Chinook Salmon O. tshawytscha, subyearling Coho Salmon O. kisutch, and yearling Coho Salmon densities, although the relationships varied among the species–age cohorts and some relationships changed during the spring sampling season. Cover and wood density were also associated with salmonid densities, but the relationships were weaker than for velocity and depth. Habitat configuration was associated with salmonid densities as well, although the relationships varied among the species–age cohorts and between habitat types. For example, within backwaters, subyearling Chinook Salmon densities were highest close to the main-stem river but yearling Coho Salmon densities were highest far from the main stem. Additionally, subyearling Chinook Salmon and Coho Salmon densities were highest within intermediate-width side channels, while yearling Coho Salmon densities exhibited a more complex response to side channel width. Conclusion Our results indicate that both microhabitat conditions and spatial configuration influence juvenile salmonid densities within off-channel habitats. These results also suggest that restoration practitioners should carefully weigh trade-offs among design alternatives because different habitat configurations will differentially benefit certain species or life stages.

Contrasting responses of soil organic and inorganic carbon pools under plant invasion in tropical coral islands

AbstractPlant invasions pose significant threats to biodiversity and ecosystem functioning, but their impact on soil carbon (C) pools in island ecosystems remains underexplored. This study examined the responses of soil total C (TC), organic C (SOC), inorganic C (SIC), and microbial‐derived C (i.e., amino sugars (ASs) and glomalin‐related soil proteins (GRSP)) in tropical island forests invaded by Cassytha filiformis, Eupatorium odoratum, and Wedelia biflora. Results revealed that invasions substantially reduced aboveground and belowground biomasses of local plant communities with increasing invasion degree, yet the soil TC pool size remained nearly unaffected due to increased SIC offsetting decreased SOC. The effects on soil C pools depended on the invasive species and sampling season. E. odoratum and W. biflora invasions significantly reduced microbial‐derived C concentrations (ASs and GRSP) but increased their contribution to the SOC pool during the wet season, whereas C. filiformis invasion reduced microbial‐derived C only in the dry season. The study highlights the tradeoff between SOC and SIC in regulating soil C pools and emphasizes the need for context‐specific management strategies. Despite the stable soil TC pool, the loss of SOC's multifunctional benefits necessitates targeted strategies to mitigate invasions' adverse effects on ecosystem health and carbon storage.

Distribution and Diversity of Coastal Fish in Fresh and Oligohaline Waters: An Example of the Largest Baltic Sea Estuary of the Neva River

ABSTRACTUnderstanding how low salinity gradients (0‰–5‰) influence fish life cycles is critical for clarifying principles of fish assemblage formation in estuarine ecosystems. This study is intended to provide a foundation for predicting changes in fish populations amidst ongoing surface salinity decreases in the Baltic Sea. In the Neva River Estuary, differences in fish diversity and distribution between fish assemblages in freshwater and oligohaline areas were assessed using beach seine and multi‐mesh gillnet surveys. The use of multiple sampling gears greatly enhanced understanding of fish distribution across salinity gradients. Fish assemblages were analysed depending on the different areas of the estuary, seasons of sampling, salinity and confounding environmental variables such as water temperature and depth. Salinity was the major influencing factor for the surf zone fish assemblages and a season of sampling was the main factor for coastal assemblages of larger fish studied with the gillnets. Fish assemblages in the surf zone exhibited significant but gradual changes in freshwater and marine‐estuarine fish occurrence and abundance along the critical oligohaline barrier ‘δ‐horohalinicum’ (0.5‰–1.9‰). Although freshwater species showed high occurrence and abundance throughout the estuary, their juveniles were less abundant in the oligohaline surf zone with salinity ≥ 2‰, where small‐size marine‐estuarine and euryhaline species predominated. Coastal multi‐mesh gillnet catches showed remarkable similarity between assemblages of larger fish in freshwater and oligohaline areas. Differences in species richness and diversity indices were not pronounced throughout the salinity gradient; the decline in freshwater species was offset by an increase in marine‐estuarine and euryhaline species.

Distribution and key influential factors of comammox in drained and waterlogged soils of zoige plateau peatland

Peatlands are important carbon and nitrogen reservoirs, playing crucial roles in nitrogen cycling. During microbially-driven nitrogen cycling, nitrous oxide (N2O, 298 times global warming potential of CO2) can be emitted, exacerbating global warming. Complete ammonia-oxidizing bacteria (comammox), a newly discovered group of prokaryotes, can independently oxidize ammonia directly to nitrate, bypassing the nitrite stage, and thereby reducing N2O production associated with the traditional two-step nitrification process. However, information on comammox distribution and its key influential factors in plateau peatlands remains scarce. Thus, this study chose Zoige plateau peatland in China to collect soil samples from different soil types (drained and waterlogged), across different seasons (non-growing and growing), and at various depth (0–100 cm) to assess comammox abundance and community composition. Additionally, soil properties were analyzed and correlated with comammox abundance and community composition to identify the key factors affecting comammox distribution. Comammox abundance varied significantly across soil types, depth, and sampling seasons. Waterlogged soils demonstrated higher comammox abundance than drained soils. In waterlogged soils, comammox abundance showed higher during growing season than non-growing season, while the opposite trend was observed in drained soils. Regardless of soil types, comammox abundance decreased with increasing soil depth. In soils of Zoige plateau peatland, comammox clades A.1, A.2, A.3 and B.1 were identified, with clade B.1 dominating the comammox community. Both Nitrospira sp. CG24A (clade B.1) and Candidatus Nitrospira nitrificans (clade A.1) showed great seasonal variations. Soil properties, including moisture, pH, carbon, and nutrients, collectively influenced comammox abundance and diversity. Among these factors, NH4+-N was the main factor affecting comammox abundance, while moisture primarily drove community distribution. These findings provide valuable insights into comammox distribution, enhancing our understanding of its potential role in mitigating N2O emissions and thus nitrogen cycling in plateau peatland soils.

Quantification of soil nutrient stocks and stoichiometric ratios in Eucalyptus pellita biomass plantation chronosequence in Papua New Guinea

Eucalyptus pellita biomass tree plantations have been widely established in the native grasslands of Markham Valley in Papua New Guinea for bioenergy production and carbon capture. However, the impacts of converting grasslands to energy plantations, and the ensuing soil transformations across the plantation chronosequence, remain largely unexplored. Such land use transitions are associated with depletion of C sinks, increased C emissions, and potential implications for climate change. This study aimed to evaluate dynamic changes in key soil physico-chemical properties, as well as nutrient stocks of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP), alongwith their stoichiometric ratios. A chronosequence of E. pellita plantations aged 2-, 4-, 7- and 10-years along with native grassland sites, was examined across two sampling seasons (January and June). The results indicated significant (p < 0.05) impacts of tree stand age on SOC and TP concentration and stocks, while TN remained unaffected. Soil NH4+-N concentration declined with the plantation age, contrasting with relatively steady NO3–-N levels across the chronosequence. SOC and TP stocks within the top 45 cm of soil depleted at rates of 0.19 Mg (Mega Gram) ha-1y-1 and 0.011 Mg ha−1 y-1, respectively. The broader stoichiometric ratio of C:N (> 25:1) observed in soils of 4- and 7-year-old plantations suggest potential nitrogen immobilization and mineral N deficiency to tree nutrition. Conversely, the C:P ratios across the chronosequence were < 200, favoring the net mineralization of organic P compounds. Overall, afforestation of grasslands with E. pellita for biomass production does not appear ecologically beneficial in the short-term (<10 years), when considering only the belowground SOC sequestration potential.