Nutrient Concentrations Research Articles

Full life cycle assessment of insect biomass allows estimation of bioflows across water, air, and land

AbstractAs global environmental change continues, animals face uncertain habitat availability and quality that influences life cycle phenology and population dynamics. For decades, the population abundance and emergence patterns of burrowing mayflies have been used as a sentinel for water quality changes in large freshwater systems around the world. Despite reduced point source pollutants, evidence is mounting that the interactions among habitat loss, contaminants, and changing climate could be causing declines in mayfly production and shifts in emergence timing. We combined radar observations with traditional field measures to identify changes in mayfly populations from nymph to adult. We studied Hexagenia sp. secondary production in a large reservoir, Lake Seminole, which has contrasting water sources and land use on each arm that could contribute to differences in emergence patterns. We predicted that mayfly secondary production would be higher, and emergence would be earlier in the Chattahoochee arm versus the Flint arm because of differences in available nutrients and temperature. Benthic declines in abundance and biomass followed radar observations of emergence. Mean annual water temperature was similar, with the Flint arm having less seasonal variation. Mayfly growth was similar across the lake, but production was higher in the upper Flint arm, perhaps because of temperature stability, higher nutrient concentrations, and more lotic conditions. The natural abundance of nitrogen‐stable isotopes in mayflies showed distinct patterns between the arms and from nymph to adult. Linking benthic sampling with radar observations verified our capability to track mayfly biomass across the landscape and begin to calibrate previous measures of production with radar‐derived abundance. Coupling radar observations with stable isotope and tissue nutrient measurements allowed us to further quantify the subsidies moving from aquatic to terrestrial ecosystems, setting the framework to examine both historic and future population changes and mayfly contributions to cross‐ecosystem subsidies.

PHYSICO-CHEMICAL ANALYSIS OF OGUTA LAKE WATER AND ITS EFFECT ON PHYTOPLANKTON POPULATION

Samples were collected from the three sampling stations namely; Up, Mid and Downstream respectively to investigate the effect of nutrients concentration on the phytoplankton in Oguta Lake. The methods used were electrometric, argentometric titration, phenate spectrophotometric, colorimetric, cadmium reduction and acetone extraction spectrophotometric methods were used to determine the pH of water sample, chlorides, sulphate, ammonia, phosphorus, nitrate, nitrite, chlorophyll-A, conductivity, turbidity, chemical oxygen demand, copper, colour, total dissolved solid, respectively. However, serial dilution was carried out using the spread plate or pour plate method was used to determine the microbial analysis of the sample. At the end of these researches, the Physico-chemical parameters analysed showed that Oguta Lake had total dissolved solids values of 6.50 ± 0.06mg/l, 6.50 ± 0.14 and 6.50 for upstream, mid stream and downstream respectively. The result showed there was no significance total dissolved solids difference between the various stream points (P0.05). the colour of the Lake showed significant difference ranging from 17.00 ± 1.41 and76.00 V 1.41 in upstream and downstream and the lowest value at upstream. The pH range in this study indicates that the water may be acidic (5.54-7.31). Phytoplankton assemblages obtain across the three stream points showed only three divisions and 78 species. The identified divisions and species are comprised of Eurcharyta (44), Cyanophyta (25) and Chlorophyta (9). Eurkaryta recorded 100%, 5% and 15% abundance in upstream, midstream and downstream respectively, while Cyanophyta recorded the highest abundance at downstream with 75%, Chlorophyta only was identified at the midstream and was least abundance with 23%. The phytoplankton diversity indices done showed that downstream was most diverse having the highest Shannon Weiner Index and Evenness Index of 3.631 and 1.212 respectively. In relation to physicochemical and phytoplankton abundance, the findings in this study is contradictory to some researches. They reported positive correlation of phytoplankton with phosphate and nitrate. There was negative correlation of phosphate with Eurkaryta and Chlorophyta, except for Cyanophyta that showed positive correlation with phytoplankton but not very significant. These low levels of phosphate and nitrate may be the cause of low phytoplankton levels.

Sustainable control of invasive plants: Compost production, quality and effects on wheat germination

Invasive plant species pose significant ecological threats worldwide, affecting the stability and biodiversity of local ecosystems. As a result of their control, a considerable amount of plant biomass is produced, which can be used to produce various value-added products. Five different composts were prepared from three invasive plant species found in Latvia – Reynoutria japonica, Solidago canadensis, Lupinus polyphyllus. The stages of composting have been investigated and recommendations for process optimization have been made based on the quality characterization of the final compost. The quality of the prepared invasive plant biomass composts has been evaluated based on the main plant nutrient concentration, humic substance concentration, and mineral contents. The allelopathic lupin alkaloid concentration throughout the composting process has been evaluated and shows a consistent reduction. Obtained compost quality complies with the EU regulations for fertilizing products and soil amendments thus it can be considered equivalent to industrially produced compost and vermicompost. Seed germination tests confirm that compost prepared from invasive plants is suitable for plant growth and comparable to commercial composts. Based on pilot-scale composting results, recommendations for invasive plant composting have been suggested.

Bacterial endophyte Pseudomonas mosselii PR5 improves growth, nutrient accumulation, and yield of rice (Oryza sativa L.) through various application methods

BackgroundPseudomonas spp. have drawn considerable attention due to their rhizospheric abundance and exceptional plant growth-promoting attributes. However, more research is needed on the optimal application methods of Pseudomonas mosselii for rice growth, nutrient accumulation, and yield improvement. This research explored the application of the endophytic bacterium P. mosselii PR5 on rice cultivar BRRI dhan29 with four treatments: control, seedling priming, root drenching, and bacterial cell-free culture (CFC) foliar application.ResultsPR5 led to better rice growth, improved nutrient acquisition, and higher yields compared to the control, regardless of the application method used. The highest results in fresh weight of root (146.93 g/pot), shoot (758.98 g/pot), and flag leaf (7.88 g/pot), dry weight of root (42.16 g/pot), shoot (97.32 g/pot), and flag leaf (2.69 g/pot), and grains/panicle (224.67), were obtained from seedling priming treatment, whereas root drenching resulted in maximum plant height (105.67 cm), root length (49.0 cm), tillers/pot (23.7), and panicles/pot (17.67). In all three application methods, rice grain yield per pot was higher in PR5 inoculated treatments, compared to the control. The amount of P, Mg and Zn in the shoot and N, P, Ca, Mg and Si content in the flag leaf was significantly increased along with effective suppression of naturally occurring blast disease in bacterial CFC foliar application, validated by multivariate analysis.ConclusionOur results indicated that rice seedlings priming with PR5 improved rice growth, yield and nutrient uptake, whereas CFC foliar application significantly increased the concentration of most nutrients in the rice plant and suppressed the naturally occurring rice blast disease. This research highlights the significant potential of P. mosselii PR5 in enhancing rice growth, yield, and nutrient uptake, particularly through seedling priming and CFC foliar application methods.

Application of Internet of Things (IoT) on Monitoring EC and pH Values for Fertigation System

This paper introduces a novel Internet of Things (IoT) based fertigation control system designed to enhance traditional agricultural practices in Malaysia, particularly in rural areas. The system integrates a fertigation approach, combining fertilization and irrigation, with smart devices and a NodeMCU ESP32 microcontroller to automate the tracking of data from liquid fertilizer mixtures. By utilizing EC and pH sensors, the system accurately monitors the nutrient concentration and pH levels of the fertilizer mix, with data displayed on an IoT platform for real-time observation and control. This approach mitigates common issues such as overfertilization and inefficient nutrient use, offering significant improvements over manual data collection methods. The system's performance was validated, showing successful monitoring and control of the fertilization process, leading to enhanced plant health and crop quality. Key findings indicate that the system's integration with IoT technology provides a more efficient, automated solution for managing fertilizer applications, reducing labor and time while ensuring optimal plant nutrient levels. The study also highlights the potential for future development, including the integration of additional sensors and advanced data analytics to optimize fertigation practices further. The implementation of this IoT-based system represents a significant advancement towards sustainable agriculture, offering practical benefits for Malaysian farmers and setting a foundation for further innovation in fertigation technology.

Dietary full-fat or defatted black soldier fly larvae can replace protein sources with no detrimental effect on growth performance or intestinal health of nursery pigs.

This work aimed to determine the effects of dietary full-fat or defatted black soldier fly larvae (BSFL) to replace protein sources on growth performance, blood parameters, intestinal morphology, and intestinal microbiota in nursery pigs and to investigate the effects of dietary defatted BSFL at up to 30% at the expense of protein sources on growth performance in nursery pigs. In Exp. 1, a total of 36 barrows with an initial body weight of 7.0kg (standard deviation = 0.8) were allotted to 3 dietary treatments in a randomized complete block design with 4 replicate pens per treatment and 3 barrows per pen. A corn-soybean meal (SBM)-whey-based control diet was prepared with soy protein concentrate and fish meal as additional protein supplements. Two additional diets were prepared to include 20% full-fat BSFL or 20% defatted BSFL to replace soy protein concentrate and fish meal to maintain the same energy and nutrient concentrations in all diets. In the 28-day feeding trial, pigs fed the diet containing defatted BSFL tended to consume more feeds (P < 0.10) than other groups during days 14 to 28 and the overall period. On day 28, the serum blood urea nitrogen in pigs fed the control diet was less (P < 0.05) than that fed the full-fat or defatted BSFL, but fecal score and jejunal morphology did not differ among the treatment groups. Relative abundance of Mycoplasma in the ileal digesta was less (P < 0.05) in the pigs fed the diet containing full-fat or defatted BSFL compared with the control group. In Exp. 2, a total of 192 pigs with an initial body weight of 7.8 (standard deviation = 1.2kg) were randomly allotted to one of 4 dietary treatments in a randomized complete block design with 6 replicate pens per treatment and 4 barrows and 4 gilts per pen. A control diet was mainly based on corn, SBM, fermented SBM, fish meal, and spray-dried plasma protein. Three additional diets were prepared to contain 10%, 20%, and 30% defatted BSFL to replace SBM, fermented SBM, fish meal, and spray-dried plasma protein to maintain for the same energy and nutrient concentrations. Average daily gain, average daily feed intake, gain:feed, and fecal score were not affected by increasing dietary defatted BSFL. Overall, dietary black soldier fly larvae did not compromise growth performance or intestinal health in nursery pigs. Black soldier fly larvae can be used in nursery pig diets to replace other protein sources without negative effects.

Native woody species depend on the soil microbiome to establish on burned soils, while non‐native do not

Abstract Wildfires are important natural disturbances with profound ecological impacts. However, our understanding of how to restore plant–soil microbiome interactions following wildfires remains limited, revealing a key knowledge gap in post‐wildfire ecosystem restoration. To assess the restoration of plant‐microbiome interactions in fire‐affected ecosystems, we conducted greenhouse experiments simulating wildfire effects on soil collected from Maulino Coastal Forest of central Chile, a biodiversity hotspot. We measured the plant height and photosynthesis over 90 days, and two‐year survival probability, of three common native (Aristotelia chilensis, Nothofagus glauca and N. alessandrii) and three non‐native species (Eucalyptus globulus, Pinus radiata and Genista monspessulana) planted in three soils (unburned, burned and burned soil inoculated with the native microbiome). Available nutrient concentrations (N, P and K) and activities of microbial enzymes (dehydrogenase, β‐glucosidase and urease) were also measured over 360 days. Available nutrient concentrations were consistently higher in burned and burned‐inoculated soils than in unburned soils. Enzyme activities in unburned and burned‐inoculated soils remained higher than in burned soil, indicating that the native microbiome restored microbial enzyme activities. The increase in height over 90 days was lower in burned soils compared with unburned soils for native species. However, inoculation with the native microbiome mitigated this negative effect, resulting in height increases similar to those in unburned soils. For non‐native species, burning and inoculation had negligible effects on the height increases. Similar patterns were observed for the increase in photosynthetic rate, with native species showing a reduced rate in burned soils, which was offset by microbiome inoculation, while non‐native species were unaffected by both treatments. Survival probability of native species declined in burned soil, but was the same in burned‐inoculated soil as in unburned soil. That of non‐native species was unaffected by burning or by inoculation with the native microbiome. Synthesis and applications. Native microbiomes are evidently promising tools to safeguard ecosystem functionality and mitigate species extinction risks arising from climate change and human‐induced wildfires. We advocate integrating microbiomes into future active restoration strategies for fire‐affected ecosystems.

Seasonal and long-term variations of nutrients in Liaodong Bay, China: Influencing factors and ecological effects

Nutrients are essential for marine primary productivity and have a critical role in maintaining the structure and function of marginal. Variations in nutrient levels in sea ecosystems can influence ecological disturbances significantly. The Liaodong Bay (LDB) is a semi-enclosed marginal sea in northern China. It has experienced severe eutrophication since the 1990s, leading to considerable environmental challenges. Understanding of seasonal and long-term nutrient dynamics in the LDB is limited. We examined seasonal datasets collected in May (spring), August (summer), November (autumn), and March (winter) of 2019, and analyzed long-term trends through historical records spanning multiple decades. Nutrients accumulated during autumn/winter but were depleted during spring/summer. A low concentration of dissolved inorganic phosphate led to an increased nitrogen ratio exceeding the Redfield ratio (>16) during winter, spring, and summer, driven by phytoplankton growth. In late-autumn, nutrient concentrations increased, with ratios approaching the Redfield ratio. Phosphorus limitation prevailed in spring, summer, and winter, while silicon limitation dominated in autumn. Dissolved inorganic nitrogen and nitrogen ratios in the LDB increased sharply since the 1980s, peaking before declining after 2013. Dissolved silica and silicon ratios decreased steadily, stabilizing in recent years. These trends imply a shift from nitrogen-to-phosphorus limitation, influenced by riverine inputs and atmospheric deposition. These nutrient fluctuations may have significant ecological effects, including dinoflagellate abundance, algal blooms, and jellyfish blooms. Our analyses highlight the complexity of nutrient dynamics and positive impact of local nutrient-reduction policies implemented in recent years in improving the environmental quality of the LDB.

Spatial Distribution of Fine Roots in Pinus tabuliformis and Populus tomentosa and Their Competition in Soils Response to Nutrient Availability and Proximity

Developing high-efficiency mixed forests or converting low-efficiency pure forests into near-natural mixed forests with optimal structure and function is a crucial aspect of forest management. In the initial stages of afforestation or stand improvement, fertilization and planting distance significantly influence the formation and development of mixed forests. This study investigated how nutrients and planting distance affect root competition between five-year-old Chinese pine (Pinus tabuliformis) and one-year-old Chinese white poplar (Populus tomentosa) and identified the factors influencing the competitive ability of these two species. Field planting experiments used three fertilization gradients (63 g·m−2, 125 g·m−2, and 250 g·m−2) of Stanley compound fertilizer with an N:P:K ratio of 2:1:1 and two planting distances (25 cm and 50 cm). Each experimental group was planted in circular plots with a radius of 0.5 m, yielding a total of nine plots. The effects of different fertilization concentrations and planting distances on root distribution were analyzed both horizontally and vertically. Pearson correlation analysis was used to assess the relationship between roots and soil nutrients, while Levins’ niche overlap formula evaluated the differences in root competition between the species. Furthermore, principal component analysis quantified the relationships between impact factors and the root competitiveness of the two species. Results indicated that both species primarily allocated their fine root biomass to the shallow 0–10 cm layer. Pinus tabuliformis primarily extended to the southwest, while Populus tomentosa predominantly grew to the north. Both species exhibited enhanced root growth at moderate nutrient concentrations of 125 g·m−2. At a planting distance of 50 cm from Pinus tabuliformis, Populus tomentosa seedlings demonstrated superior root growth compared to those planted 25 cm apart. Pinus tabuliformis demonstrated greater competitive ability in the deeper 10–30 cm soil layers compared to Populus tomentosa, which showed the opposite pattern in the shallow 0–10 cm layers. Furthermore, available phosphorus (contribution rate of one impact factor on the competitiveness indexes, CR: −0.998), organic matter (CR: −0.978), total nitrogen (CR: −0.947), and alkali-hydrolysable nitrogen (CR: −0.937) significantly negatively impacted the competitiveness indexes of Pinus tabuliformis. The fine root surface area, volume, and length of Populus tomentosa also significantly negatively affected its competitiveness indexes, with all contribution rates exceeding an absolute value of 0.847. Results indicated that the root distributions of Pinus tabuliformis and Populus tomentosa overlapped spatially, with each species exhibiting advantages in different regions. Therefore, in future plantation reconstruction and forest management, it is essential to thoroughly evaluate root, soil, and fertilizer factors, adjusting planting distances accordingly, to effectively mitigate competition between the two species and successfully establish a mixed forest.

Linking fish bioturbation to life history in a eutrophic wetland: An analysis of fish contributions to internal nutrient loading

Abstract Bioturbation (sediment disturbance by animal actions) effects on nutrient cycling and nutrient levels in surface waters are difficult to quantify, in part because the diversity and magnitude of species‐specific influences are poorly understood. These influences may have consequences for the management of the trophic state of freshwater ecosystems. Fish cause bioturbation in freshwater and marine ecosystems by digging in benthic sediments, manipulating periphyton mats while searching for prey and scraping hard substrates while feeding. We used experimental enclosures (2.25 m2) to quantify bioturbation‐mediated phosphorus (P) and nitrogen (N) regeneration from sediment by three species of fish that differ in interactions with the benthos (largemouth bass, Micropterus salmoides; tilapia, Oreochromis spp.; and sailfin catfish, Pterogoplichthys spp.) in shallow eutrophic wetlands in Southern Florida. Tilapia are omnivores that include detritus in their diet (winnowing or ingesting sediments) and dig nests in soft sediments year round, sailfin catfish actively burrow into substrate and consume detritus (digging and ingesting sediments), and largemouth bass are piscivores that do not routinely interact with the benthos when feeding but may dig nests in soft sediment in spawning season (January–April). We quantified the amount of suspended flocculent organic matter and changes in water column nutrients (total phosphorus [TP] and total nitrogen [TN]) in 2‐week trials for each species and estimated the portion of nutrient increases relative to fishless controls that could be attributed to bioturbation‐mediated internal nutrient loading through suspension of organic matter (as opposed to excretion or other sources of nutrient loading). Water column nutrient concentrations increased with increasing biomass for all species, but the bioturbation contribution differed by species. Largemouth bass increased water column nutrient concentrations (TP: 86% and TN: 5% relative to controls) but did not influence water column suspended particulate matter through bioturbation of sediment. Tilapia increased water column nutrients a modest amount (TP: 8%; TN: 15%), of which a small portion was attributed to bioturbation (c. 18% of TP). Sailfin catfish raised water column nutrients substantially (TP: 105%; TN: 46%) and up to 100% of the increased TP was attributed to bioturbation. Sailfin catfish also suppressed algal growth and TP accumulation on the sides of the enclosures and reduced nutrient concentrations of the flocculent sediments. Our results were consistent with our hypothesis that behaviour and foraging traits affect bioturbation contributions to nutrient loading. The results also demonstrated that species with similar net effects like largemouth bass and sailfin catfish, added nutrients via different mechanisms (i.e. excretion vs. bioturbation). Considering the feeding strategies and interactions with the substrate of common fish species may assist managers in meeting nutrient reduction goals for eutrophic wetlands and managed freshwater systems.

Biofertilizer based on &lt;i&gt;Agrobacterium &lt;/i&gt;as a key to food security

Background: The concept of food security is contingent upon the fulfillment of two fundamental requirements: physiological and socioeconomic. The former comprises providing sustenance that is both safeguarded and enhanced in line with people’s nutritional needs and priorities, whereas the latter includes the mechanisms by which these needs are supplied. The objective is to ensure a state of robust and healthy well-being. As a sustainable solution, biofertilizers play a pivotal role in addressing the challenges of food security. Biofertilizers represent a cost-effective and environmentally friendly solution, with the potential to enhance soil productivity through nitrogen fixation. They also enhance crop yield by increasing the concentration of nutrients. Access to functional foods derived from biofertilizer-enhanced yields may contribute to improved dietary diversification and overall well-being. Objective: The objective is to isolate and screen the most active nitrogen-fixing bacterium as a basis to a new biofertilizer. Methods: The isolation of nitrogen-fixing bacteria was conducted using the soil sowing technique. The selection of nitrogen-fixing bacteria was based on their morphophysiological characteristics. Bacterial growth was evaluated by viable cell count. Cultivation of the selected bacterium occurred in both flasks (on a shaker) and a bioreactor to compare growth conditions. The stimulatory effect of the selected bacterium on seed germination was assessed based on the final germination rate. The selected bacterium identified through molecular taxonomy. Results: A total of 100 pure cultures were isolated, from which nitrogen-fixing bacteria were selected. The cultivation conditions for these bacteria were optimized regarding pH, temperature and process duration in a flask on a shaker. Strain NB4 exhibited the most favorable development under optimal settings. Additionally, cultivation parameters for this strain were optimized in a laboratory bioreactor. Notably, a bacterial liquid culture water solution comprising 1.5% strain NB4 facilitated complete germination of wheat (Triticum aestivum L.), seeds and produced high-quality sprouts. The 16S rRNA gene sequence of strain NB4 was submitted to the GenBank database under accession number MT670424.1, identifying it as Agrobacterium Pusense RP 1. Conclusion: This research aimed to develop an effective biofertilizer to tackle the pressing issue of food security. The project’s cornerstone was Agrobacterium pusense RP 1, nitrogen-fixing strain isolated and identified through rigorous research. Keywords: Isolation and identification of nitrogen-fixing bacteria, cultivation in bioreactor, germination of wheat seeds, Agrobacterium pusense.

Sequential migrations of diverse fish community provide seasonally prolonged and stable nutrient inputs to a river.

Animal migrations transport resources among spatially separate ecosystems, effectively linking them. In freshwater ecosystems, numerous fish species migrate between mainstream rivers or lakes and their tributaries, providing resources and nutrients during their spawning migrations. Multiple migratory species travel to the same destinations and contribute such nutrients, but knowledge remains limited about how the diversity of migratory animals influences the recipient ecosystem. We investigated how migrations of diverse fish community from Lake Biwa, Japan contribute to nutrient inputs in one of the lake's tributary rivers and how they influence the ecosystem. Sequential migration of six fish species continued for 8 months of a year, causing high-level nutrient concentration and primary production. The fish-derived resources were taken up by diverse members of the river community. Our results emphasize the extent to which migrations of diverse animals seasonally extend and stabilize the resource subsidy and how they extend pronounced effects on the recipient ecosystems.

Integrated Modeling Approach to Assess Freshwater Inflow Impact on Coastal Water Quality

The quality of freshwater input from tributaries of the Western Mississippi Sound (WMSS) impacts the quality of coastal water. Hydrological and hydrodynamic models can be coupled to assess the impact of freshwater inflow from coastal watersheds. This study aims to compare the performance of a hydrodynamic model and a hydrological–hydrodynamic coupled model in detecting the effect of freshwater inflow from the coastal watersheds of the state of Mississippi into the WMSS. A hydrological model, the Soil and Water Assessment Tool (SWAT), and a hydrodynamic model, the visual Environmental Fluid Dynamics Code (vEFDC), were coupled to evaluate the difference between the hydrodynamical modelling approach, which employs an area-weighted approach to define flow and nutrient concentrations, and the more recent coupling model approach, which uses a hydrological model to determine the flow and nutrient load of the model. Furthermore, a nutrient load sensitivity analysis of the effect of freshwater inflow on water quality in the WMSS was conducted in addition to assessing the repercussions of tropical depressions. Hydrological assessments of the major tributaries watersheds of Saint Louis Bay (SLB) at the WMSS were performed using the SWAT model. After calibration/validation of the SWAT model, the streamflow output from the SWAT was incorporated into the vEFDC model. Finally, hydrodynamic simulation of the SWAT-vEFDC model was conducted, and water quality output was compared at different SLB locations. The salinity, dissolved oxygen, total nitrogen (TN), and total phosphorus (TP) were assessed by comparing the vEFDC and SWAT-vEFDC outputs. The results indicated that hydrological input from the SWAT alters the flow and nutrient concentration results as compared to an area-weighted approach. In addition, a major impact on the concentration of TN and TP occurred at the location where the freshwater flows into SLB. This impact diminishes further away from the point of freshwater inflow. Moreover, a 25% nutrient load variation did not demonstrate a difference in water quality at the WMSS besides TN and TP in a post-tropical depression scenario. Therefore, the SWAT-vEFDC coupled approach provided insights into evaluation of the area-weighted method, and of hydrological model output to the hydrodynamical model, the effect of freshwater inflow into coastal waters, and nutrient sensitivity analysis, which are important for integrated coastal ecosystems management.

Analysis of Selected Macro- and Microelement Components in the Indigenous Soybean Cultivars from Regions of the Western Himalaya in India

The need to focus on traditional crops for food security has been realized across the globe. ‘Bhat’ is an indigenous soybean variety from the Indian Himalayan Region that has been neglected in recent times due to changing agricultural choices. The present study was conducted on 52 indigenous soybean accessions collected from different villages of Uttarakhand, a hilly state in Northern India, to determine the concentrations of various macro- and microelements in the crop. The analysis used the HHXRF (handheld X-ray fluorescence) spectroscopic technique and atomic absorption spectroscopy (AAS). The findings reveal that the ‘bhat’ is an extremely nutrient-rich crop with calcium being the most significant macronutrient (highest concentration of 27,300 ppm), followed by phosphorus, potassium, and sulphur found in the bhat seeds. The study suggests that samples from Pauri Garhwal (Gwad Khirsu, Bironkhal, Sripur), Tehri (PratapNagar, Singoli), Chamoli (Paini, and Agastyamuni) villages were rich in all the major macronutrients. Among the micronutrients, silicon was found to be the most dominant with the highest concentration of 1920 ppm. This was followed by the dominance of iron, zinc, and manganese in descending order of abundance. Tipri, Chandola Rai Goonth, Chopdiun, and Paini villages were found to have the highest concentrations of microelements. The statistical data analysis confirms that seed samples from different regions are significantly similar in terms of nutrient concentrations, except for Si and Fe, thereby indicating that ‘bhat’ from any of the villages is equally good for consumption. However, seed samples from certain regions were found to be contaminated with heavy metals, indicating soil pollution, which demands attention towards current agricultural practices. The findings show that the crop is an exceptional source of essential and quasi-essential elements and should be promoted to benefit the hill populations.

Biotic and abiotic properties mediating sediment microbial diversity and function in a river-lake continuum.

A river-lake system plays an important role in water management by providing long-term and frequent water diversions. However, hydrological connectivity in the system can have a profound effect on sediment microbial communities through pH, nutrient concentrations, and benthos invertebrates. Consequently, identifying the key environmental factors and their driving mechanisms is vital for microbial adaptation strategies to extreme environments. In this study, we analyzed the significant difference in sediment bacterial and fungal community structures and diversity indices among Dongting Lake and its tributary rivers, which worked as a typical river-connected lake ecosystem. There were significant differences in biotic and abiotic environments in the sediment habitats of Dongting Lake and its tributary rivers. Random forest analysis revealed that pH and Mollusca were found to be the most important abiotic and biotic variables for predicting both bacterial and fungal community structures, respectively. The beta diversity decomposition analyses showed that the bacterial and fungal community compositional dissimilarities among different sections were dominated by species replacement processes, with more than half of the OTUs in each section being unique. Notably, both biotic and abiotic factors affected the number and the relative abundance of these bacterial and fungal unique OTUs, leading to changes in community composition. Mollusca, pH, TP, NO3-N, and NH4-N were negatively related to the relative abundance of Actinobacteria, Acidobacteria, Gemmatimonadetes, Planctomycetes, and Ascomycota, while Annelida and ORP were positively related to the relative abundance of Actinobacteria and Gemmatimonadetes. Additionally, PICRUSt analysis revealed that the functional dissimilarity among lakes and rivers was strengthened in unique species compared to all species in bacterial and fungal communities, and the changes of functional types helped to improve the habitat environment in the main Dongting Lake and promote the process of microbial growth. From our results, the role of macrozoobenthos and physicochemical characteristics in driving the sediment microbial community spatial variations became clear, which contributed to further understanding of the river-lake ecosystem.

The structure of epiphytic and planktonic bacterial assemblages under two contrasting lake regimes

Abstract In contrast to the macrophyte‐dominated regime (MDR), the phytoplankton‐dominated regime (PDR) in shallow lakes is characterized by relatively high nutrient concentrations, excessive phytoplankton growth and turbid water column. Some floating‐leaved plants can grow under both regimes and aid in reducing nutrient concentrations in water bodies. Their epiphytic bacterial assemblages play an essential role in the health and adaptation of these plants; however, there is limited understanding of this plant‐bacteria interaction. Here, we used 16S rRNA gene‐based high‐throughput sequencing to compare the diversity, composition and co‐occurrence patterns of planktonic and epiphytic bacterial assemblages associated with the submerged roots and floating leaves of Trapa natans, growing under the PDR and MDR in Lake Taihu, China. Alpha diversity of PDR epiphytic bacterial assemblages was lower than in MDR. The opposite trend was observed for planktonic bacterial assemblages. We detected a strong compositional difference between epiphytic and planktonic bacterial assemblages. Bacterial assemblages found on root and leaf surfaces showed only minimal compositional overlap with those in the water column. The composition of epiphytic bacterial assemblages differed more between the two regimes than did planktonic bacterial assemblages. The PDR co‐occurrence network of bacterial assemblages was more complex than that of the MDR, with the PDR epiphytic habitats enriched more network keystone taxa. The proportion of positive edges was also greater in the PDR networks of epiphytic bacterial assemblages than in the epiphytic MDR networks, whereas it was lower in the planktonic bacterial network from the PDR than from the MDR. The comprehensive view of the diversity, composition and co‐occurrence patterns of epiphytic and planktonic bacterial assemblages of MDR and PDR in large shallow lakes provided by our results showed that the structure of epiphytic bacterial assemblages was mediated by both host and water properties, and the observed core taxa and network keystone species may play an important role in maintaining plant growth and adaptation to environmental change.

Exploring marine zooplankton dynamics through carbon stable isotope signatures in a recently marine submarine volcano

Submarine emissions of gases from hydrothermal vents alter the surrounding chemical environment, influencing species responses to the resulting environmental gradients. The 2011 underwater eruption of the Tagoro volcano off the coast of El Hierro in the Atlantic Ocean changed the physical and chemical conditions, impacting the distribution of pelagic fauna. Post-eruptive stages from 2013 to 2018 revealed changes in both benthic and pelagic communities, with continuous eruptions further affecting local carbon cycle through shifts in nutrient concentrations and isotopic composition. The lowest δ13C values in zooplanktonic primary consumers were found in areas directly influenced by the Tagoro submarine volcano. Although the mixing model results show that phytoplankton is the primary carbon source for copepods, contributing an average of 28.3% of their carbon, magmatic CO2 and seawater dissolved inorganic carbon each account for approximately 17–18%. The isotopic signatures reveal a gradient of enrichment in copepods, reflecting the influence of inorganic nutrient and gas emissions from the volcano's centre to its periphery within the marine ecosystem. This data is useful for understanding the worldwide significance of environmental stressors such as volcanic eruptions on marine organisms.

Assessing the Potential Impacts of Contaminants on the Water Quality of Lake Victoria: Two Case Studies in Uganda

Nutrients are essential for the growth of aquatic life; however, in excess, they can result in a decline in water quality, posing serious risks to both human and aquatic organisms. Human activities, such as urbanisation, industry, and farming, can increase the amount of nutrients and other elements that reach receiving waterbodies like Lake Victoria in Uganda, which can be problematic at elevated levels. There is therefore a strong need to evaluate recent changes in pollutant concentrations and their potential negative effects. To contribute to this gap and to explore the pollutant changes in Lake Victoria, a series of water chemistry data (phosphate, nitrate, potassium, ammonium, sodium, sulphate, silica and chlorine) was collected between 2016 and 2023 in Uganda’s Napoleon Gulf (NG) and Murchison Bay (MB), primarily by the Ministry of Water and Environment (MWE). These locations were chosen based on their vicinity to expanding urban centres and agriculture, and they are also areas where fishing frequently occurs. The datasets were collected at different water depths (0.5–24 m). Data were analysed with the use of IBM’s Statistical Package for the Social Sciences (SPSS 28.0) software and confirmed the excessive concentrations of pollutants within MB compared to NG. The analysis identified the different nutrient types that exceeded internationally recognised thresholds relating to acceptable water quality during the data collection period. Seasonal variations were observed, during the dry season; nutrient levels, however, in NG showed higher nutrient concentrations during the wet season. The study’s capacity to inform local authorities and policymakers about such potential major sources of pollution is of crucial importance for beginning to address the potential impacts on human health and aquatic life.

Large igneous provinces played a major role in oceanic oxygenation events during the mid-Proterozoic

AbstractLow atmospheric oxygen levels during the mid-Proterozoic were occasionally interrupted by transient high oxygen levels. The cause of mid-Proterozoic ocean redox variability remains unclear. Here we investigate mercury chemostratigraphy across the Jixian section of North China Craton through two oxygenation intervals. Abnormal spikes in mercury concentration and excursions of mercury isotopes are observed in the Dahongyu and Hongshuizhuang formations, which occur just below the two oxygenation intervals, respectively. These mercury anomalies suggest that the two oxygenation events were preceded by subaerial volcanism. Furthermore, the two oxygenation intervals show increased nutrient concentrations and negative shifts in mercury isotopes, indicating that enhanced weathering and terrestrial nutrient influx occurred during oxygenation intervals. We infer that in the breakup setting of the Columbia supercontinent, large igneous province volcanism and its efficient low-latitude weathering could rapidly increase terrestrial nutrient influx into the ocean, promoting oceanic productivity and a pulsed rise in oxygen levels.

Growth, Productivity and Nutrient Uptake Rates of Ulva lactuca and Devaleraea mollis Co-Cultured with Atractoscion nobilis in a Land-Based Seawater Flow-Through Cascade IMTA System

To advance environmentally friendly technologies in the aquaculture of Atractoscion nobilis, and simultaneously to diversify seafood production, a 79-day trial was conducted to assess the performance of Ulva lactuca and Devaleraea mollis cultured in the effluent from A. nobilis in a land-based integrated multi-trophic aquaculture (IMTA) system in southern California, USA. Water quality and performance of macroalgae were measured weekly. The impacted factors on the growth of macroalgae and nutrient uptake rate of macroalgae were assessed. The specific growth rate of juvenile A. nobilis was 0.47–0.52%/d. Total ammonia nitrogen in effluents of A. nobilis tanks ranged from 0.03 to 0.19 mg/L. Ulva lactuca and D. mollis achieved an average productivity of 24.53 and 14.40 g dry weight (DW)/m2/d. The average nitrogen content was 3.48 and 4.89% DW, and accordingly, the average nitrogen uptake rate was 0.88 and 0.71 g/m2/d, respectively. Temperature and nutrient concentration were key factors impacting macroalgae growth, and light intensity also impacted the growth of D. mollis. The high protein content of U. lactuca and D. mollis would make them good for use as human or animal food, or for use in other industries. Research on the interaction effects between seawater exchange rates and aeration rates on the performance and nutrient uptake rates of macroalgae will be conducted in future studies.