Nutrient Enrichment Research Articles

The influence of flow, nutrient enrichment and aquatic macrophytes on benthic microalgal dynamics in a perched temporarily closed estuary

This study investigated the benthic microalgal dynamics in a temporarily closed microtidal estuary situated along a degraded stretch of coastline, where estuaries are impacted by development, flow modification, and nutrient pollution. The near natural, perched uMdlotane Estuary experienced regular high flow conditions that maintained the open mouth state for 40% of the study period. Increased nutrient input originated from agricultural-return flow derived from the extensive catchment sugarcane farming (55.9%). No notable temporal differences were recorded for the benthic microalgal biomass (range: 0–41.3 mg m−2). The benthic diatom diversity and evenness indices ranged between 0.6 and 3.1 H′ and 0.2–1 J′, respectively. Higher benthic microalgal biomass (14.9 ± 15.6 mg m−2) coincided with lower diatom diversity (1.3 H’) in the lower reaches. The habitat stability provided by the rooted Stuckenia pectinata facilitated benthic microalgal accumulation, while the absence of sediment disturbance contributed to the decrease in the benthic diatom diversity. The benthic diatom species Cocconeis lineata, Halamphora acutiuscula, and Hantzschia amphioxys largely dominated the community. Temporal differentiation in benthic diatom composition was driven by salinity, water temperature, phosphate, and photic depth changes. The pollution tolerant species Cyclotella atomus increased in abundance (sub-dominant RA = 5%) in response to increased phosphate availability. The presence of nutrient tolerant taxa serves as an early warning of impending environmental deterioration. Implementation of an adaptive management approach supported by monitoring is required to facilitate timely interventions to prevent the loss of ecosystem functionality induced by nutrient enrichment.

The Influence of Adding Banana Peel Powder on the Quality of Pan Bread

This study’s objective was to show how nutritious banana peel powder. Moreover, to use BPP as a cheap alternative to wheat flour in bread. The results of BPP at different concentrations (0,2,6 and 10%), as well as the sensory qualities of bread. The BPP is also regarded as a beneficial protein source (7.6%), ash (9.66%) and.. Physical and chemical characteristics of bread made by partially replacing wheat flour with banana peel powder were examined. It has been established that banana peel contains a significant amount of nutrients which should not be disregarded or squandered. banana peel can become a value-added product in the food sector by being processed into powder. The powder’s flowability declines. banana peel was discovered to have a high tapped density 0.41 g/ml, and Carr’s Index 14.21 %, pH value was 6.15. This powder was high in total dietary fiber 17.99 %. Additionally, functional properties of this powder were high, the water-holding capacity 6g/g, oil-holding capacity 3.4g/g and swelling capacity 15.33 ml/g. As a result, this study showed that the ripe banana peel powder has a chance to be used as a functional food ingredient. It is advised that BPP be utilized up to 6 % to complement and enhance the qualitative qualities of bread as a result of this research at a level that has several health advantages. numerous dishes gain nutritional value from the banana peel. banana peels as a cheap and abundant source, utilization, and enrichment of nutrients.

Nutrients retention function indications in the water quality of the floodplain area on the lower Batanghari River

The Lower Batanghari River often experiences mass deaths of fish. This could be a symptom of eutrophication caused by nutrient enrichment in the water bodies. Floodplain areas are important in reducing parts of these nutrient loadings. This study aimed to examine water qualities related to the nutrient retention function within the Batanghari River floodplain ecosystem. A sampling expedition was conducted in April-May 2021, during a dry season transition period. Sampling was conducted at 20 sampling points stretching over +200 km long within the river and its tributaries. These sampling points were categorized as main river channels, tributaries, and floodplain swamps and lakes. The water quality parameters measured were temperature, pH, conductivity, dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP), and total organic matter (TOM). The main river TP concentrations ranged from 0.21-0.33 mg/L, suitable for fishery activities. The overall sampling point groups have distinct characteristics regarding their DO, TP, and TOM values. The average TP in floodplain lakes was found significantly lower (t(13)=8.636, p<0.05) than in the river. Meanwhile, a decrease in TN up to 90% was also found in its lower main river channel. These lower nutrient concentrations along the river floodplain gradients indicate a nutrient retention function. Thus, to reduce eutrophication impacts, floodplain conservation is becoming important.

Isoprene Production and Its Driving Factors in the Northwest Pacific Ocean

AbstractMarine isoprene plays a crucial role in the formation of secondary organic aerosol within the remote marine boundary layer. Due to scarce field measurements of oceanic isoprene and limited laboratory‐based studies of isoprene production, assessing the importance of marine isoprene on atmospheric chemistry and climate is challenging. Calculating in‐field isoprene production rates is a crucial step to predict marine isoprene concentrations and the subsequent emissions to the atmosphere. The distribution, sources, and dominant environmental factors of isoprene were determined in the Northwest Pacific Ocean in 2019. The nutrient enrichment in the Kuroshio Oyashio Extension (KOE) surface seawater, driven by the upwelling and atmospheric deposition, promoted the growth of phytoplankton and elevated the isoprene concentration. This was confirmed by observed responses of isoprene to nutrients and aerosol dust additions in a ship‐based incubation experiment, where the isoprene concentrations increased by 70% (t = 4.417, p &lt; 0.001) and 35% (t = 2.387, p &lt; 0.05), respectively. Biogenic isoprene production rates in the deck incubation experiments were positively related to chlorophyll a, temperature, and solar radiation, with an average production of 7.33 ± 4.27 pmol L−1 day−1. Photochemical degradation of dissolved organic matter was likely an abiotic source of isoprene, contributing to approximately 14% of the total production. Driven by high isoprene production and extreme physical disturbance, the KOE showed very high emissions of isoprene of 46.0 ± 13.0 nmol m−2 day−1, which led to a significant influence on the oxidative capacity of the local atmosphere.

Enriched biochar enhances height growth performance of Anthocephalus cadamba on severely degraded Spodosols in East Kalimantan

Tropical Spodosols are highly fragile and disturbed Spodosols remain unproductive at conventional management practices due to the inherent infertility of the soils. These soils developed from quartz rocks and are characterized by the presence of E albic and B spodic horizons. This study was conducted to determine the effect of enriched biochar application on height growth of jabon (Anthocephalus cadamba) stands planted on spodosols. Research plots were arranged to comply with a 2-factors completely randomized design (CRD) procedure – 3 levels of rate of biochar treatment (A1 = 0%v, A2 = 2%v and A3 = 5%v) and 2 levels of liquid organic fertilizer enrichment (B0 = without enrichment and B1 = with enrichment). There were 3 replicates for each treatment consisted of 28 Jabon (Anthocephalus cadamba) plants at 2.5 m x 3 m spacing, therefore a total of 504 plants were observed in this study. Results showed that the rate of biochar and nutrient enrichment gave a significant effect on the height growth of jabon plants (A. cadamba), the best height growth was obtained at the enriched biochar treatment rate of 5%v (A3B1).

Eutrophication and loss of riparian shading influence food quality and trophic relation in stream food webs

Eutrophication induced by excessive inputs of nutrient is one of the main stressors in aquatic ecosystems. Deforestation in riparian zones alter riparian shading, which together with eutrophication is expected to exert a complex control over stream food webs. We manipulated two levels of riparian shading (open canopy vs. shading canopy) and nutrient supply (ambient vs. nutrient addition) in three headwater streams to investigate the individual and combined effects of eutrophication and loss of riparian shading on carbon sources and nutritional quality of biofilms, and the subsequent trophic effects on macroinvertebrate grazers. Nutrient enrichment increased the autochthonous carbon (i.e., algae especially diatoms) indicated by fatty acid (FA) biomarkers within biofilms and grazers. The nutritional quality indicated by eicosapentaenoic acid (EPA) content of biofilms was increased with nutrient enrichment and more so with the combined effect of an increase in riparian shading, consequently leading to an increase in the nutritional quality, density, and biomass of grazers. In particular, the trophic linkages between biofilms and grazers were mainly influenced by EPA concentration in the biofilms, and strengthened with the combined effects of riparian shading and additional nutrients. Our study emphasizes the nutritional significance of EPA for consumers at higher trophic levels and proposes its potential as an indicator for monitoring the health of aquatic ecosystems.

Multi-omics analysis reveals the molecular response to heat stress in a “red tide” dinoflagellate

Background“Red tides” are harmful algal blooms caused by dinoflagellate microalgae that accumulate toxins lethal to other organisms, including humans via consumption of contaminated seafood. These algal blooms are driven by a combination of environmental factors including nutrient enrichment, particularly in warm waters, and are increasingly frequent. The molecular, regulatory, and evolutionary mechanisms that underlie the heat stress response in these harmful bloom-forming algal species remain little understood, due in part to the limited genomic resources from dinoflagellates, complicated by the large sizes of genomes, exhibiting features atypical of eukaryotes.ResultsWe present the de novo assembled genome (~ 4.75 Gbp with 85,849 protein-coding genes), transcriptome, proteome, and metabolome from Prorocentrum cordatum, a globally abundant, bloom-forming dinoflagellate. Using axenic algal cultures, we study the molecular mechanisms that underpin the algal response to heat stress, which is relevant to current ocean warming trends. We present the first evidence of a complementary interplay between RNA editing and exon usage that regulates the expression and functional diversity of biomolecules, reflected by reduction in photosynthesis, central metabolism, and protein synthesis. These results reveal genomic signatures and post-transcriptional regulation for the first time in a pelagic dinoflagellate.ConclusionsOur multi-omics analyses uncover the molecular response to heat stress in an important bloom-forming algal species, which is driven by complex gene structures in a large, high-G+C genome, combined with multi-level transcriptional regulation. The dynamics and interplay of molecular regulatory mechanisms may explain in part how dinoflagellates diversified to become some of the most ecologically successful organisms on Earth.

Phytoplankton communities of the west coast of Florida – multiyear and seasonal responses to nutrient enrichment

Blooms of the harmful algae species Karenia brevis are frequent off the southwest coast of Florida despite having relatively slow growth rates. The regional frequency of these harmful algal blooms led to the examination of the dominant estuarine outflows for effects on both K. brevis and the phytoplankton community in general. There is comparatively little information on the growth rates of non-Karenia taxonomic groups other than diatoms. A seasonally based series (Fall, Winter, and Spring) of bioassay experiments were conducted to determine the nutrient response of the coastal phytoplankton community. Treatments included estuarine waters (Tampa Bay, Charlotte Harbor, and the Caloosahatchee River) applied in a 1:25 dilution added to coastal water to mimic the influence of estuarine water in a coastal environment. Other treatments were 5–15 μM additions of nitrogen (N), phosphorus (P), and silica (Si) species, amino acids, and N (urea) + P added to coastal water. Incubations were conducted under ambient conditions with shading for 48 h. Analyses of dissolved and particulate nutrients were coupled with HPLC analysis of characteristic photopigments and taxonomic assignments of biomass via CHEMTAX. The coastal phytoplankton community, dominated by diatoms, cyanophytes and prasinophytes, was significantly different both by bioassay and by season, indicating little seasonal fidelity in composition. Specific growth rates of chlorophyll a indicated no significant difference between any controls, any estuarine treatment, P, or Si treatments. Conditions were uniformly N-limited with the highest growth rates in diatom biomass. Despite differing initial communities, however, there were seasonally reproducible changes in community due to the persistent growth or decline of the various taxa, including haptophytes, cyanophytes, and cryptophytes. For the one bioassay in which K. brevis was present, the slow growth of K. brevis relative to diatoms in a mixed community was evident, indicating that identifying the seasonally based behavior of other taxa in response to nutrients is critical for the simulation of phytoplankton competition and the successful prediction of the region's harmful algal blooms.

Managing the Red Lake Nation’s and Minnesota’s largest lake: monitoring and paleolimnology support a site-specific standard for Upper and Lower Red Lakes (Red Lake Nation and Minnesota, United States)

Burge DRL, Edlund MB, Bowe S, Bowe K, Anderson JP, Bouchard RW, Heathcote AJ, Leavitt PR, Engstrom DR. 2023. Managing the Red Lake Nation’s and Minnesota’s largest lake: monitoring and paleolimnology support a site-specific standard for Upper and Lower Red Lakes (Red Lake Nation and Minnesota, United States). Lake Reserv Manage. 40:1–17. Water quality and the ability of lakes to provide benefits such as recreation and aquatic life are negatively impacted by climate change, aquatic invasive species, and nutrient enrichment. To address these lake-management challenges, regionally tailored water quality criteria need to assign achievable and protective goals while minimizing assessment errors. In Minnesota, when lakes exceed state water-quality standards, restoration plans are developed and implemented based on eco-regional standards, or in cases where it is determined that the regional standard is not appropriate, a site-specific standard may be developed. Upper Red Lake and Lower Red Lake, located within the boundaries of the Red Lake Indian Reservation (the Red Lake Nation) in northwestern Minnesota (United States), have been recently experiencing cyanobacteria blooms, as well as routinely exceeding the regional water quality criteria for total phosphorus and chlorophyll a. The last 20 yr of water quality monitoring suggest a stable recent history with no significant trends. To extend this time perspective, biogeochemical evidence from paleolimnology was used to reconstruct a 150 yr history for these 2 large, shallow lakes to determine whether site-specific water quality standards might be recommended. Biogeochemical evidence (e.g., sedimentation rates, phosphorus fractions, biogenic silica, diatom community composition, and fossil algal pigments) from 10 sediment cores revealed complex sedimentary dynamics together with a small gradual increase in limnological productivity over the last 2 centuries. Despite the implied productivity change, diatom-inferred phosphorus showed no significant increase among the sediment cores. Furthermore, the reconstructed total phosphorus values were within the range of modern monitored values. Because the paleolimnological evidence suggests little change to the aquatic ecology of the Red Lakes over the last 150 yr, and monitoring data show regular exceedance of regional TP standards with no trend in the last 20 yr, site-specific water quality standards are deemed appropriate for this large, shallow lake system.

Cover crop functional types alter soil nematode community composition and structure in dryland crop-fallow rotations

Increasing dryland cropping intensity by integrating cover crops into crop-fallow rotations can add diversity and alter soil ecosystem functions, including improvements in soil nutrient and water retention and cycling, and suppression of soil-borne pests. However, the use of cover crops can also carry the risk of increasing the abundance of plant-parasitic nematodes that could undermine system productivity. Here, we examined how the integration of diverse cover crops of different functional groups: Poaceae [forage oat (Avena sativa L.)]; Brassicaceae [forage rape (Brassica napus L.)]; and Fabaceae [common vetch (Vicia sativa subsp. sativa L. and fababean (Vicia faba L.) in monocultures and mixtures into a dryland crop-fallow rotation altered soil nematode community composition and structure relative to conventional fallows. We found that cover crop mixtures had greater diversity and complexity of free-living nematodes, indicating enhanced cycling of energy and nutrients (enrichment index >50 %) compared to monocultures. Furthermore, using a structural equation modelling approach, we showed the abundance of free-living nematodes is driven primarily by cover crop residue quality (C:N ratio, and cellulose content) and marginally by cover crop quantity (biomass). The grass-legume mixture had the highest abundance of plant-parasitic nematodes (Pratylenchus neglectus and Merlinius brevidens) but also fostered robust soil food webs with complex soil nematode trophic interactions, indicating promotion of soil ecosystem functions related to N and C cycling and overall improvement in soil health. The results indicate bottom-up effects of cover crops on soil nematode communities are modulated by cover crop functional type and mixture composition. Consequently, cover crops with appropriate traits must be selected if soil health is to be improved via suppression of plant-parasitic nematodes, promotion of free-living nematodes, and enhancement of soil food web complexity.

Reuse of sediment as a soil conditioner in a semiarid region dominated by subsistence farming: sediment characterization at the regional scale and effects on maize crop

PurposeThe increasing demand for fertilizers and their rising prices has led to the search for new nutrient sources, especially in rural areas where family farming predominates. In this study, we assessed the potential of reusing sediment deposited in surface reservoirs as a soil conditioner in a semiarid region, focusing on two features: the characterization of sediment physicochemical properties at the regional scale and the effect of the substrate containing sediment on the growth and physiology of maize.MethodsSediment from the beds of 14 reservoirs was investigated, and two of them were used for the preparation of substrate for maize cultivation. Differences between the physicochemical properties of the sediments were analyzed using ANOVA and Tukey’s test at a significance level of 0.05. The experimental design of the plant experiment was entirely randomized, in a factorial arrangement of two sources and four doses of sediment: 25, 50, 75, and 100% of the economic dose of 100 t ha−1 previously proposed in the study region. Two treatments were considered as controls: a substrate containing only soil and a treatment containing soil and chemical fertilizer. The data for each treatment were submitted independently considering the doses and sediment sources, and the means were compared by Tukey’s test.ResultsIn general, nutrient contents were higher in the sediment of the surface reservoirs than in the soil. For instance, the concentrations of nitrogen and potassium were three to 10 times higher in the sediment, compared to the soil, and the organic matter content was up to six times higher. In the plant experiment, the dose and source of the sediments influenced all of the analyzed variables. The addition of sediments to the soil increased the chlorophyll content, photosynthesis rate, and growth of the leaves in relation to the treatment containing only soil. There were no significant differences between the biomass production and the plants’ nutrient extraction with the largest dose of the most enriched sediment when compared to the treatment with chemical fertilizer.ConclusionsThe experiment of maize plant growth showed the feasibility of using sediment deposited in reservoirs as a soil conditioner due to the enrichment of nutrients, organic matter, and fine particles. Therefore, sediment reuse has potential to improve livelihoods and food security, as well as contributing to a circular economy. However, prior analysis is required to avoid soil contamination and to set the most appropriate sediment dose, due to the high spatial variability of the sediment characteristics.

The Assembly Process of Free-Living and Particle-Attached Bacterial Communities in Shrimp-Rearing Waters: The Overwhelming Influence of Nutrient Factors Relative to Microalgal Inoculation.

The ecological functions of bacterial communities vary between particle-attached (PA) lifestyles and free-living (FL) lifestyles, and separately exploring their community assembly helps to elucidate the microecological mechanisms of shrimp rearing. Microalgal inoculation and nutrient enrichment during shrimp rearing are two important driving factors that affect rearing-water bacterial communities, but their relative contributions to the bacterial community assembly have not been evaluated. Here, we inoculated two microalgae, Nannochloropsis oculata and Thalassiosira weissflogii, into shrimp-rearing waters to investigate the distinct effects of various environmental factors on PA and FL bacterial communities. Our study showed that the composition and representative bacteria of different microalgal treatments were significantly different between the PA and FL bacterial communities. Regression analyses and Mantel tests revealed that nutrients were vital factors that constrained the diversity, structure, and co-occurrence patterns of both the PA and FL bacterial communities. Partial least squares path modeling (PLS-PM) analysis indicated that microalgae could directly or indirectly affect the PA bacterial community through nutrient interactions. Moreover, a significant interaction was detected between PA and FL bacterial communities. Our study reveals the unequal effects of microalgae and nutrients on bacterial community assembly and helps explore microbial community assembly in shrimp-rearing ecosystems.

Pathways linking nutrient enrichment, habitat structure, and parasitism to host-resource interactions.

Human activities simultaneously alter nutrient levels, habitat structure, and levels of parasitism. These activities likely have individual and joint impacts on food webs. Furthermore, there is particular concern that nutrient additions and changes to habitat structure might exacerbate the size of epidemics and impacts on host density. We used a well-studied zooplankton-fungus host-parasite system and experimental whole water column enclosures to factorially manipulate nutrient levels, habitat structure (specifically: mixing), and presence of parasites. Nutrient addition increased infection prevalence, density of infected hosts, and total host density. We hypothesized that nutrients, mixing, and parasitism were linked in multiple ways, including via their combined effects on phytoplankton (resource) abundance, and we used structural equation modeling to disentangle these pathways. In the absence of the parasite, both nutrients and mixing increased abundance of phytoplankton, whereas host density was negatively related to phytoplankton abundance, suggesting a mixture of bottom-up and top-down control of phytoplankton. In the presence of the parasite, nutrients still increased phytoplankton abundance but mixing no longer did, and there was no longer a significant relationship between host density and phytoplankton. This decoupling of host-resource dynamics may have resulted from reduced grazing due to illness-mediated changes in feeding behavior. Overall, our results show that the impact of one human activity (e.g., altered habitat structure) might depend on other human impacts (e.g., parasite introduction). Fortunately, carefully designed experiments and analyses can help tease apart these multifaceted relationships, allowing us to understand how human activities alter food webs, including interactions between hosts and their parasites and resources.

New interactive functional indicator approach for river health assessment in an Asian temperate river: Comprehensive analysis of water chemistry, physical habitat, land use, and the biological disturbance of invasive alien species

Elucidating the responses of aquatic communities to environmental (e.g., chemical, habitat, and flow regime) and biological disturbances is essential to the maintenance and restoration of healthy ecosystems. This study investigated the interactions between environmental and biological disturbance factors and functional indicators of ecological health in 99 sampling sites along a temperate river. Variance tests and multivariate statistical tools, such as non-metric multidimensional scaling (NMDS) and generalized linear models (GLMs), were employed to evaluate the responses of functional indicator guilds and ecological river health to various in-stream chemical, physical, habitat, and land-use pattern factors along with the biological impact of invasive alien species (IAS). Variance testing revealed significant variation (χ2 > 6.2 and p < 0.05) in common species abundance and ecological functional guilds among spatial groups according to chemical pollution levels, land-use intensity, and land-use patterns. NMDS analysis and GLMs based on trophic, habitat, and tolerance guilds, and the results of the multi-metric index of biological integrity for fish, indicated statistically significant patterns in response to environmental disturbance, particularly chemical degradation associated with nutrient (nitrogen and phosphorus) enrichment and organic pollution, loss of gravel and cobble substrates, and intensified agricultural land use. The spatial pattern of IAS abundance was also significantly correlated with the alteration in fish community structures. This study underscores the often-unnoticed impact of high IAS abundance on river health, and its interactions with chemical and physical degradation resulting from agricultural and urban land uses. In summary, this study highlights the importance of addressing multiple environmental and biological disturbances to maintain and conserve the health of river systems.

Phosphorus-driven regime shift from heterotrophic to autotrophic diazotrophs in a deep alpine lake

Biological nitrogen fixation plays a critical role in maintaining primary production, particularly in systematic nitrogen deficiency. However, little is known about the dynamics within diazotrophic community facing ongoing nutrient enrichment in freshwater lakes. Here, a consecutive five-year investigation on diazotrophic community was conducted in Lake Fuxian, an oligotrophic deep alpine lake on the trajectory to eutrophic state. Results showed a regime shift from heterotrophic to autotrophic diazotrophs induced by total phosphorus (TP) enrichment. Specifically, heterotrophic diazotrophs dominated the diazotrophic community when TP was lower than 21.8 μg/L, whereas heterotrophic diazotrophs or diazotrophic Cyanobacteria randomly dominated when TP ranged between 21.8 μg/L and 28.8 μg/L. When TP was higher than 28.8 μg/L, diazotrophic Cyanobacteria accounted for 60.4%-97.7% of the total N2-fixers, indicating diazotrophic biodiversity significantly declined under TP enrichment scenario. Moreover, the dominance of diazotrophic Cyanobacteria further facilitated phytoplankton growth, which strengthened positive feedback between phytoplankton and phosphorus under nitrogen deficiency conditions. This is the first report on the threshold-like state responses of freshwater diazotrophs to environmental drivers. Our study expands the knowledge of the diazotrophic dynamics in freshwater ecosystems and contributes quantitative evidence of ecological thresholds for future environmental policymaking.

A perspective on how glyphosate and 2,4-D in wetlands may impact climate change

An increase in herbicide use is occurring due to a growing population and herbicide-resistant crops in agriculture, which has resulted in more herbicide tolerant target species. Glyphosate and 2,4-Dichlorophenoxyacetic acid (2,4-D) are two of the most commonly used herbicides worldwide and are more recently being used in combination in pre-mixed commercial formulas. Subsequently, herbicide contamination of wetlands will increase exposure of microorganisms to multiple chemical stressors. Methane is a potent greenhouse gas naturally emitted from wetlands, but herbicides may disrupt biogeochemical processes leading to an unbalanced methane cycle. We review the impacts of these herbicides on aquatic microbial communities from glyphosate-derived nutrient enrichment and 2,4-D inhibition of methane oxidation, and examine how these altered metabolic processes may lead to increased methane production in wetlands. The response of wetland ecosystems to herbicide contamination will vary across regions, in part due to the complexity of microbial communities, however, this perspective gives a glimpse into the potential global implications of continuing herbicide use on wetlands and demonstrates the importance for research on ecosystem-level co-stressors.

Role of formulated bacterial consortia in biofortifying tomato fruits with nutrients: A nutritional, genomic and metagenomic analysis

Nutrient deficiencies are a major problem that is prone to affect millions of people around the globe. Biofortification, a process of enriching nutrients in staple food crops is an effective method to tackle this malnutrition-associated disorder. Tomato (Solanum lycopersicum) is a globally consumed crop and therefore is a suitable candidate for biofortification. Many plant growth-promoting bacteria are reported to have the ability to enhance nutrient content in plants. In the present study, we have investigated the ability of two bacterial consortia (consortia-1 –co-culturing Lysinibacillus sp. strain VITKC-5 and Acinetobacter Sp. strain VITKC_6; and consortia-2 –co-culturing Lysinibacillus sp. strain VITKC-5 and Enterobacter sp. strain VITVLC-4) in the nutrient enrichment of tomato fruits. The results were then correlated with the elevated expression of nutrient transporter genes. Furthermore, the effect of these bacterial formulations on the indigenous microbiome has also been evaluated through metagenomic analysis. The application of bacterial formulations significantly improved the nutrient content when compared to the control (untreated) group. These findings advocate that PGPB-assisted biofortification has the potential to alleviate nutrient deficiency in humans.

Short-Term PE Generation Processes in the Soils of a Farmer Plots Network in the Madagascar Highlands: Actors and Drivers

Carbon sequestration in agricultural soils, through the accumulation of high-quality organic matter, represents great potential to mitigate climate change and simultaneously improve soil fertility. Such a challenge is particularly important and relevant in developing tropical countries like Madagascar, where soil carbon storage is vulnerable to climatic variations and where fertilization is generally applied through amendments in organic matter of various origins. The priming effect (PE) is considered here as the stimulation of the mineralization of soil organic matter (SOM) by a supply of fresh organic matter (FOM). PE results from different microbial processes driven by specific biotic and abiotic parameters. Depending on the processes involved, it has been suggested that PE could either counteract SOM accumulation or promote it. The objective of the present study was to explore the relationships between certain agricultural practices (type of crop, quality of fertilization, association with trees), the potential intensity of PE, as well as several abiotic (texture, quantity and quality SOM, nutrient enrichment) a1nd biotic (biomass and phylogenetic composition of microbial communities) factors which have been proposed in the literature as specific determinants of the different PE generation mechanisms. The soils for this study come from a network of farms in a commune in the Highlands of Madagascar. The PE, generated by a supply of 13C-enriched wheat straw, could not directly correlate with agricultural treatments. However, several indirect correlations could be found via several specific abiotic and microbial determinants that are discussed in terms of soil fertility restoration.

Application of water quality indices and geostatistical methods for analyzing mountain lakes in relation to anthropogenic influences and catchment features: a case study in East Sikkim, India

Abstract Water quality, pollution level, and trophic conditions were assessed in Aritar Lake located in the Himalayas in East Sikkim, India, in relation to geo-environmental influences and anthropogenic activity in its catchment. A comprehensive method involving indexing and multivariate analyses was used. Geostatistical tools were employed to interpolate seasonal and spatial deviations in water quality, and nutrient and organic load distribution. Lake water nutrient index (NI) values were between 4.61 and 7.31, and 2.65 and 4.69 during pre- and post-monsoon seasons, respectively, indicating significant nutrient enrichment and eutrophic conditions. For both seasons, the estimated organic pollution index (OPI) showed class II contamination (contamination starting), with post-monsoon values being higher. The study shows clear signs of eutrophication and early organic pollution. Effective management plans and sustainable tourism practices may benefit the lake, by reducing contamination and protecting the integrity of its ecosystem.

Monitoring Reclamation of Plant Biodiversity and Soil Parameters in an Area of Bauxite Mine Spoils (A Case Study of Greece)

In order to assess plant biodiversity in bauxite mine spoils, a fully randomized experiment was carried out with five treatments to find the ones that would best restore the soil and plant biodiversity in the spring seasons of 2020 and 2021. In the studied area, 68 plant species belonging to 54 genera with high ecological value that comprise the flora and represent 19 families were identified. Concerning the herbaceous plant species richness in several treatments, the highest value was calculated in the treatment of sludge (52 plant species), followed by the treatment of soil in the area (39), whereas the lowest plant species richness was recorded in the treatment of fertilization (27), the incorporation of soil with soils (26), and control (27), so our findings indicate that the area where sludge was applied showed the highest nutrient enrichment as well as the highest plant biodiversity, plant cover, and biomass. Apart from sludge, the mineral soil around the area was also composed of some materials that provided good results with regard to plant parameters. The main problems with the properties of the mine spoil material were the low organic matter content and the low clay percentage. The use of sludge, probably in combination with the soil around the area, might alleviate these problems. The plant parameters (Shannon diversity index, plant cover, and biomass) correlated positively and significantly with most of the macronutrients and micronutrients in soils.