Nutrient Cycling Research Articles

Some recent advancements in fish nutrition and feed technology in India

The advancements in fish nutrition outlined here provide a promising picture of a thriving and sustainable aquaculture industry. By embracing these innovations, exploring alternative ingredients, optimising nutrient utilisation, and tailoring feed strategies to specific systems, we can confidently navigate the future of seafood production, ensuring food security for generations to come while safeguarding the health of our planet. In the pursuit of sustainable aquaculture, researchers have focused on eco-friendly nutritional strategies, aiming to minimize environmental impact and conserve natural resources. Nutrient recycling, a fundamental concept in sustainable aquaculture, involves utilizing fish waste as organic fertilizer for plant crops resulting in a circular economy and reducing the carbon footprint. . KEYWORDS :Fish Nutrition, Feed Technology, Recent Advancement

The Function of Autophagy in the Initiation, and Development of Breast Cancer.

Autophagy is a significant catabolic procedure that increases in stressful conditions. This mechanism is mostly triggered after damage to the organelles, the presence of unnatural proteins, and nutrient recycling in reaction to these stresses. One of the key points in this article is that cleaning and preserving damaged organelles and accumulated molecules through autophagy in normal cells helps prevent cancer. Since dysfunction of autophagy is associated with various diseases, including cancer, it has a dual function in tumor suppression and expansion. It has newly become clear that the regulation of autophagy can be used for the treatment of breast cancer, which has a promising effect of increasing the efficiency of anticancer treatment in a tissue- and cell-type-specific manner by affecting the fundamental molecular mechanisms. Regulation of autophagy and its function in tumorigenesis is a vital part of modern anticancer techniques. This study discusses the current advances related to the mechanisms that describe essential modulators of autophagy involved in the metastasis of cancers and the development of new breast cancer treatments.

Conservation and management of Himalayan biodiversity in climate change perspectives

Diverse agro-ecosystems are the bedrock of life-sustaining goods and services, ranging from water and energy to food production and the facilitation of energy and nutrient cycling. These ecosystems not only benefit humanity but also play a crucial role in supporting the balance of ecosystems worldwide. Biodiversity conservation and management are paramount as they directly impact the suitability and resilience of ecosystems, ultimately affecting the livelihoods of both human and non-human species. The Indian Himalayan Region (IHR) boasts extraordinary biodiversity; however, efforts to conserve and harness its bio-resources for technological advancements or useful products lag behind many other nations. Climate change exacerbates these challenges, affecting every aspect of agriculture and biodiversity across tropical and subtropical regions. In response to this urgent context, there is a pressing need to review existing conservation and management strategies while identifying areas for improvement. Analyzing the diverse requirements and methods of conserving biodiversity involves prioritizing the sustenance of natural processes and features inherent in our natural resources and associated ecosystems. Recognizing that natural solutions exist within these resources, landscapes, and ecosystems is pivotal. Addressing these challenges requires concerted efforts and institutional synergy among various stakeholders, including researchers, local communities, resource managers, and policymakers. Collaboration is essential to conserve biodiversity while leveraging existing or newly created opportunities and resources within ecosystems. Furthermore, revising and updating legal frameworks, policy guidelines, and other instruments are crucial steps to ensure the sustained protection of biodiversity and ecosystems. This includes safeguarding the livelihoods and food production avenues of local communities, thereby fostering sustainable development practices that prioritize both human well-being and environmental integrity.. KEYWORDS :Himalayan Biodiversity, Climate change, Conservation and Management.

Extracellular Enzyme Activity and Stoichiometry Across Vegetated and Non-Vegetated Coastal Ecosystems

The conversion of organic matter by extracellular enzymes can reveal important insights into carbon and nutrient cycling. The activity and stoichiometry of hydrolytic extracellular enzymes were investigated to assess the effects of vegetation cover and sediment characteristics on microbial-enzyme-mediated decomposition in coastal ecosystems. Extracellular enzyme activity (EEA) was quantified across transects extending from mangrove to tidal flat habitats in two New Zealand coastal ecosystems that differ in mud content (sandy: Hobson Bay, muddy: Snells Beach). We determined the activity of five key hydrolyzing enzymes: β-glucosidase (hydrolyzes cellulose to glucose); β-N-acetylglucosaminidase (catalyzes the terminal reaction in chitin degradation); alkaline phosphatase (releases soluble inorganic phosphate groups from organophosphates); β-D-cellobiohydrolase (hydrolyzes cellulose to generate cellobiose); and β-xylosidase (catalyzes hemicellulose). All enzymes involved in C acquisition and in N and P cycling had higher activity at the muddy site. No habitat differences in EEA were observed at the sandy site, whereas EEA was lower in the non-vegetated habitats for some enzymes at the muddy site. Models of microbial metabolic limitations highlighted that most habitats at both muddy and sandy sites were predominately C and P limited. The EEA in these coastal wetlands was generally lower than has been reported for other terrestrial, freshwater, and estuarine ecosystems, with values often one to two orders of magnitude lower than other wetland studies. These results can be used to advance our understanding of the biogeochemical processes underpinning the response of coastal ecosystems to land-derived nutrient and sediment inputs.

The termitaria terminator: Can Actinobolus beetles affect the relationships between termitaria and related fauna in the Brazilian Cerrado?

AbstractTermites are key components of tropical ecosystems, particularly in the Cerrado biome, where they dominate animal biomass and play crucial roles in nutrient cycling and soil formation. Their abundance and nutritional value make them primary food sources for various Cerrado animals, influencing predator diversity and several ecological interactions. Additionally, termite mounds serve as essential shelters for a wide range of fauna, aiding in thermoregulation and providing refuge from harsh environmental conditions, including wildfires. In this scenario, termitaria survival, diversity, and availability have several effects on the Cerrado fauna ecology. We present novel insights into the interaction between Actinobolus beetles and epigeous termite mounds in the Cerrado. Our field observations revealed Actinobolus beetles utilizing termite mounds for feeding and reproduction in several localities of Cerrado. These beetles access the inner portion of the termitaria, where the colony nest is located and protected by the termitaria's harder external layer and their larvae consume the termite nest structure. Actinobolus attack leads to partial or complete destruction of the colony and the creation of large hollows inside the mounds, causing deep changes in its structure. Despite the defensive mechanisms of termites, Actinobolus larvae thrive within the nest and likely ingest termites’ eggs, nymphae and adults. Furthermore, we found that the Actinobolus capsule are made of faecal pellets, instead of termitaria debris. We suggest that the interaction between Actinobolus beetles and epigeous termitaria impacts the role of termitaria in providing microclimate regulation, food and shelter for Cerrado fauna, likely having poorly understood effects on the conservation and management of Cerrado ecosystems.

A Flow‐Curvature‐Based Model for Channel Meandering in Tidal Marshes

AbstractChannel meandering is ubiquitous in tidal marshes, yet it is either omitted or weakly implemented in morphodynamic models. Here we propose a novel numerical method to simulate channel meandering in tidal marshes on a Cartesian grid. The method calculates a first‐order flow by considering the balance between pressure gradient and bed friction. To account for flow momentum shift toward meander outer banks, the flow is empirically modified. Unlike previous simplified methods that relied on the curvature of the bank, this modification is based on the curvature of the flow, making the model suitable for use in dendritic channel networks. The modified flow intrinsically accounts for the topographic steering effect, which tends to deflect the momentum toward the outer bank. As a result, the outer bank becomes steeper and erodes due to soil creep. Additionally, the outer bank experiences erosion proportional to the flow curvature. This mechanism parameterizes the direct erosion caused by flow impacting the bank through a proportionality coefficient, which modulates the rate of channel lateral migration. Deposition on the inner bank is automatically simulated by the model, triggered by reduced bed shear stress in that area. The model accurately reproduces channel lateral migration and sinuosity development, and associated processes such as meander cutoffs, channel piracies, and network reorganizations. The model provides an efficient tool for predicting marsh landscape evolution from decades to millennia, and will enable exploring how lateral migration and meandering of tidal channels affect marsh ecomorphodynamics, carbon and nutrient cycling, drainage efficiency, and pond dynamics.

Community assembly of ectomycorrhizal fungal communities in pure and mixed Pinus massoniana forests

Ectomycorrhizal (EcM) fungi play an important role in nutrient cycling and community ecological dynamics and are widely acknowledged as important components of forest ecosystems. However, little information is available regarding EcM fungal community structure or the possible relationship between EcM fungi, soil properties, and forestry activities in Pinus massoniana forests. In this study, we evaluated soil properties, extracellular enzyme activities, and fungal diversity and community composition in root and soil samples from pure Pinus massoniana natural forests, pure P. massoniana plantations, and P. massoniana and Liquidambar gracilipes mixed forests. The mixed forest showed the highest EcM fungal diversity in both root and bulk soil samples. Community composition and co-occurrence network structures differed significantly between forest types. Variation in the EcM fungal community was significantly correlated with the activities of β-glucuronidase and β−1,4-N-acetylglucosaminidase, whereas non-EcM fungal community characteristics were significantly correlated with β-1,4-glucosidase and β-glucuronidase activities. Furthermore, stochastic processes predominantly drove the assembly of both EcM and non-EcM fungal communities, while deterministic processes exerted greater influence on soil fungal communities in mixed forests compared to pure forests. Our findings may inform a deeper understanding of how the assembly processes and environmental roles of subterranean fungal communities differ between mixed and pure plantations and may provide insights for how to promote forest sustainability in subtropical areas.

Earthworm cast microbiomes differ across soil types in northern forests

Earthworms influence soil properties and element cycling, notably through the formation of casts. These biogenic structures are hotspots of microbial activity and play a role in soil carbon and nutrient dynamics. Previous research revealed that earthworm casts harbour distinct microbiomes from mineral soils under controlled laboratory conditions. But field studies are scarce, especially in northern forests currently undergoing earthworm invasion. Identifying drivers of earthworm cast microbiomes in the field and their potential differences with mineral soils and forest floors is therefore crucial to advance our understanding of their impact on soil functioning and nutrient cycling. Using a combined PLFA and DNA (ITS and 16S) approach, we characterized the fungal and bacterial communities of field-collected earthworm casts from three soil types: Luvisols, Brunisols (WRB: Cambisols), and Podzols. We compared them with those of surrounding mineral soils and forest floors. We did not find evidence of community filtering effects following gut transit and mixing of mineral soil and forest floor, as α- diversity and species richness were not reduced in casts. Cast microbiomes were dominated by taxa also found in forest floors and mineral soils. Yet they presented key differences in that they were systematically enriched in saprotrophic fungi and Bacteroidota and depleted in ectomycorrhizal fungi. Further, they were more similar to forest floor than mineral soil microbiomes. We also found that, although cast microbiomes were dominated by taxa common to casts of all sites, they differed across soil types. This finding highlights the prevailing role of pedogenesis in explaining the microbiome composition of field-aged casts. Our results also underscore the importance of sampling both forest floors and mineral soils when investigating the effects of earthworms on carbon and microbial dynamics in forest ecosystems.

Compositional and functional succession of soil bacterial communities during long-term rice cultivation on saline-alkali soils: Insights derived from a new perspective of the core bacterial taxa

The conversion of saline-alkali soils into paddy fields for long-term rice cultivation involves multiple disturbances, and as a result, soil microbial communities are altered to adapt to a changing environment. A comprehensive understanding of the succession of soil bacterial communities that occurs during this process, however, is still lacking. In the present study, we utilized data obtained from rice paddies of different cultivation years to investigate the compositional and functional succession of the soil bacterial community. We focused on core bacterial taxa that were specifically enriched at different successional stages. Generalized joint attribute modeling (GJAM) was used to identify core bacterial taxa. Results indicated that bare saline-alkali soils shared few core amplicon sequence variants (ASVs) with paddy fields. Longimicrobiaceae from the phylum Gemmatimonadetes was dominant in bare saline-alkali soils, while their dominance was subsequently replaced by Burkholderiaceae and Pedosphaeraceae, phyla affiliated with the Proteobacteria and Verrucomicrobia, after 5 years and 23 years of rice cultivation, respectively. The abundance of nitrogen metabolism functions in the core bacterial community present in bare saline-alkali soils were higher than they were in other successional stages, while sulfur metabolism functions exhibited the opposite trend. These data indicate that the role of the core bacterial taxa in mediating nutrient cycling also changed and adapted to changing soil conditions as rice cultivation became established. Redundancy analysis (RDA) indicated that the compositions of the core bacterial community in Y0, Y5s, Y10s, and Y20s groups were driven by nitrate-nitrogen content, soil pH, available phosphorus content, and the ratio of total carbon to total nitrogen, respectively. In summary, the present study provides insights into the succession of soil bacterial communities and core bacterial taxa that occur during long-term rice cultivation.

Global forest gaps reduce litterfall but increase litter carbon and phosphorus release

Ongoing global climate change and conventional forestry have led to a dramatic increase in new forest gaps, predicted to strongly impact litter turnover and nutrient cycling. Here we synthesized 8739 paired observations to quantify the impacts of naturally occurring and artificially created gaps on litterfall, litter decomposition, and the release of carbon and nutrients. Globally, forest gaps decreased annual litterfall by 29.5% and litter remaining carbon and phosphorus by 5.6%, while litter decomposition increased in the 0–20% mass loss interval. Climate and litter quality showed a major contribution to forest gap effects on litter decomposition, with gap characteristics further influencing the release of carbon and nutrients during decomposition. Our results uncovered the potential impact of escalating forest gaps on reducing litter turnover and carbon sequestration, providing support for the inclusion of gaps into global litter dynamic models to improve predictions of ecosystem material cycling responses to ongoing climate change.

Introducing Native Tree Species Alter the Soil Organic Carbon, Nitrogen, Phosphorus, and Fine Roots in Moso Bamboo Plantations

Bamboo and wood-mixed forests are management models that remarkably enhance the balance and productivity of bamboo ecosystems. However, the effects of this model on soil nutrients and enzyme activities remain largely unknown. This study compared the soil organic carbon, nitrogen, phosphorus, and enzyme activity, along with the characteristics of fine roots in pure Moso bamboo plantations (CK) and those mixed with Liriodendron chinense (ML), Sassafras tzumu (MS), Cunninghamia lanceolata (MC), and Pseudolarix amabilis (MP). The results showed that mixed forests improve carbon pools in 0–40 cm soil layers, increasing the total organic C(TOC), free particulate organic C (fPOC), occluded particulate organic C (oPOC), hot-water-extractable organic C (DOC), and mineral-associated organic C (MOC). They also increase soil total N, total P, available N, available P, NH4+-N, NO3−-N, inorganic P, organic P, and microbial biomass N. Bacterial and fungal abundances, along with enzyme activities (urease, acid phosphatase, polyphenol oxidase, peroxidase, and β-glucosidase), also improved. MP and MS were the most effective. Moreover, MS and MP supported a higher biomass and length of fine root and increased the nitrogen and phosphorus uptake of Moso bamboo. In conclusion, Sassafras tzumu and Pseudolarix amabilis are optimal for mixed planting, offering substantial benefits to soil nutrient dynamics and preventing soil quality decline in Moso bamboo forests, thereby supporting better nutrient cycling and carbon sequestration. This research offers insights into enhancing soil quality through diversified Moso bamboo forestry.

Resource partitioning of a Mexican clam in species-poor Baltic Sea sediments indicates the existence of a vacant trophic niche

Invasive species are often generalists that can take advantage of formerly unexploited resources. The existence of such vacant niches is more likely in species-poor systems like the Baltic Sea. The suspension feeding wedge clam, Rangia cuneata, native to estuarine environments in the Gulf of Mexico, was sighted for the first time in the southeastern Baltic in 2010 and a few years later in the northern Baltic along the Swedish coast. To explore possible competition for food resources between R. cuneata and the three native clams inhabiting Baltic shallow soft bottoms, stable isotope and fatty acid analyses were conducted. There was no overlap between R. cuneata and any of the native species in either stable isotope or fatty acid niches. This suggests efficient partitioning of resources; multivariate analyses indicate that separation was driven mainly by δ13C and by fatty acids reflecting diatoms and cyanobacteria, respectively (e.g. 16:1ω7 and 18:3ω3). R. cuneata reflected seasonal variation in phytoplankton more than other clams reflecting higher trophic plasticity. In conclusion, the addition of R. cuneata to the Baltic shallow soft bottoms suggests the existence of a vacant trophic niche in these sediment habitats, however the long-term effects on other species and nutrient cycling requires further studies focusing on the population dynamics of R. cuneata and its impact on the Baltic Sea ecosystem.

Decomposition of Foliar Litter from Dominant Plants of Desert Riparian Forests in Extremely Arid Regions

Litter decomposition is important for understanding the effects of habitat on nutrient cycling. In this study, we investigated the decomposition characteristics, decomposition variability, and regulatory factors restricting the decomposition rates of leaf litter in three different habitats: a flood disturbance habitat, an arid habitat, and a high-salinity habitat. The litter decomposition rates of the habitats decreased in the following order: flood disturbance habit > arid habitat > high-salinity habitat. The organic carbon, total nitrogen, and lignin residues of the litter during the decomposition period were highest in the high-salinity habitat. The litter quality was the main regulator of the release of phosphorus and cellulose residues, which exhibited different release processes and patterns in these three habitats. The litter decomposition coefficient was negatively correlated with litter carbon residue in the flood disturbance habitats, the lignocellulose index in the arid habitats, and soil urease in the high-salinity habitats. It was positively correlated with the lignocellulose index in flood disturbance habitats and litter carbon residue in high-salinity habitats. The litter quality in the flood disturbance area played a significant role in litter decomposition, while environmental quality and litter quality were the dominant factors under arid and high-salt conditions. Litter quality in the flood disturbance area played a significant role in litter decomposition, while both environmental quality and litter quality were the dominant factors under arid and salt conditions.

Autotrophy to Heterotrophy: Shift in Bacterial Functions During the Melt Season in Antarctic Cryoconite Holes.

Microbes residing in cryoconite holes (debris, water, and nutrient-rich ecosystems) on the glacier surface actively participate in carbon and nutrient cycling. Not much is known about how these communities and their functions change during the summer melt-season when intense ablation and runoff alter the influx and outflux of nutrients and microbes. Here, we use high-throughput-amplicon sequencing, predictive metabolic tools and Phenotype MicroArray techniques to track changes in bacterial communities and functions in cryoconite holes in a coastal Antarctic site and the surrounding fjord, during the summer season. The bacterial diversity in cryoconite hole meltwater was predominantly composed of heterotrophs (Proteobacteria) throughout the season. The associated functional potentials were related to heterotrophic-assimilatory and -dissimilatory pathways. Autotrophic Cyanobacterial lineages dominated the debris community at the beginning and end of summer, while heterotrophic Bacteroidota- and Proteobacteria-related phyla increased during the peak melt period. Predictive functional analyses based on taxonomy show a shift from predominantly phototrophy-related functions to heterotrophic assimilatory pathways as the melt-season progressed. This shift from autotrophic to heterotrophic communities within cryoconite holes can affect carbon drawdown and nutrient liberation from the glacier surface during the summer. In addition, the flushing out and export of cryoconite hole communitiesto the fjord could influence the biogeochemical dynamics of the fjord ecosystem.

Marine Fungal Diversity and Dynamics in the Gulf of Trieste (Northern Adriatic Sea)

Fungi contribute to different important ecological processes, including decomposition of organic matter and nutrient cycling, but in the marine environment the main factors influencing their diversity and dynamics at the spatial and temporal levels are still largely unclear. In this study, we performed DNA metabarcoding on seawater sampled monthly over a year and a half in the Gulf of Trieste (northern Adriatic Sea), targeting the internal transcribed spacer (ITS) and the 18S rRNA gene regions. The fungal communities were diverse, very dynamic, and belonged predominantly to marine taxa. Samples could be clustered in two groups, mainly based on the high (> 30%) or low relative proportion of the ascomycetes Parengyodontium album, which emerged as a key taxon in this area. Dissolved and particulate organic C:N ratio played important roles in shaping the mycoplankton assemblages, suggesting that differently bioavailable organic matter pools may be utilized by different consortia. The proportion of fungal over total reads was 31% for ITS and 0.7% for 18S. ITS had the highest taxonomic resolution but low power to detect early divergent fungal lineages. Our results on composition, distribution, and environmental drivers extended our knowledge of the structure and function of the mycobiome of coastal waters.

A data‐driven topsoil classification framework to support soil health assessment in Minnesota

AbstractSoil health assessments aim to quantify soil health status using indicators linked to ecosystem services such as yield, nutrient cycling, water cycling, or carbon storage. Many indicators are related to soil biological processes, which can be challenging to interpret because they are sensitive not only to management, but also to nonmanagement variables such as soil inherent properties, topography, and climate. Existing studies address this challenge by grouping similar soils by taxonomy, geography, or a combination of these and other variables for soil health assessment. We investigated whether grouping soils based on multiple quantitative topsoil properties could be an alternative to taxonomic or geographic groups. We used an unsupervised classification algorithm, k‐means, to cluster publicly available soil and climate data for Minnesota. Clustering into eight conceptual groups (“clusters”) based on 10 topsoil properties was determined to be the optimal algorithm output. We evaluated the ability of our soil clusters and other grouping methods to explain variance in eight soil health indicators. We found the combination of Major Land Resource Area (MLRA) and soil cluster performed best, explaining as much or more variance than other groupings for five of the eight indicators. The clusters distinguish zones of topsoil variation at the field scale, and MLRAs account for broader scale variation in climate and other landscape factors. The approach we describe is flexible and could be applied at different locations and scales to produce conceptual soil groups and associated maps to support soil health test sampling and interpretation at the field scale.

Dissecting the role of soybean rhizosphere-enriched bacterial taxa in modulating nitrogen-cycling functions

Crop roots selectively recruit certain microbial taxa that are essential for supporting their growth. Within the recruited microbes, some taxa are consistently enriched in the rhizosphere across various locations and crop genotypes, while others are unique to specific planting sites or genotypes. Whether these differentially enriched taxa are different in community composition and how they interact with nutrient cycling need further investigation. Here, we sampled bulk soil and the rhizosphere soil of five soybean varieties grown in Shijiazhuang and Xuzhou, categorized the rhizosphere-enriched microbes into shared, site-specific, and variety-specific taxa, and analyzed their correlation with the diazotrophic communities and microbial genes involved in nitrogen (N) cycling. The shared taxa were dominated by Actinobacteria and Thaumarchaeota, the site-specific taxa were dominated by Actinobacteria in Shijiazhuang and by Nitrospirae in Xuzhou, while the variety-specific taxa were more evenly distributed in several phyla and contained many rare operational taxonomic units (OTUs). The rhizosphere-enriched taxa correlated with most diazotroph orders negatively but with eight orders including Rhizobiales positively. Each group within the shared, site-specific, and variety-specific taxa negatively correlated with bacterial amoA and narG in Shijiazhuang and positively correlated with archaeal amoA in Xuzhou. These results revealed that the shared, site-specific, and variety-specific taxa are distinct in community compositions but similar in associations with rhizosphere N-cycling functions. They exhibited potential in regulating the soybean roots’ selection for high-efficiency diazotrophs and the ammonia-oxidizing and denitrification processes. This study provides new insights into soybean rhizosphere-enriched microbes and their association with N cycling.Key points• Soybean rhizosphere affected diazotroph community and enriched nifH, amoA, and nosZ.• Shared and site- and variety-specific taxa were dominated by different phyla.• Rhizosphere-enriched taxa were similarly associated with N-cycle functions.

The atmosphere: a transport medium or an active microbial ecosystem?

The atmosphere may be Earth's largest microbial ecosystem. It is connected to all of Earth's surface ecosystems and plays an important role in microbial dispersal on local to global scales. Despite this grand scale, surprisingly little is understood about the atmosphere itself as a habitat. A key question remains unresolved: does the atmosphere simply transport microorganisms from one location to another, or does it harbor adapted, resident, and active microbial communities that overcome the physiological stressors and selection pressures the atmosphere poses to life? Advances in extreme microbiology and astrobiology continue to push our understanding of the limits of life towards ever greater extremes of temperature, pressure, salinity, irradiance, pH, and water availability. Earth's atmosphere stands as a challenging, but potentially surmountable, extreme environment to harbour living, active, resident microorganisms. Here we confront the current understanding of the atmosphere as a microbial habitat, highlighting key advances and limitations. We pose major ecological and mechanistic questions about microbial life in the atmosphere that remain unresolved and frame the problems and technical pitfalls that have largely hindered recent developments in this space, providing evidence-based insights to drive future research in this field. New innovations supported by rigorous technical standards are needed to enable progress in understanding atmospheric microorganisms and their influence on global processes of weather, climate, nutrient cycling, biodiversity, and microbial connectivity, especially in the context of rapid global change.

Projected impacts of global warming scenarios on marine ecosystems: Insights from the CMIP6 model

Rising oceanic temperatures and increased heat content have triggered a decline in marine biodiversity and the degradation of ecosystem services. This study employs the Coupled Model Intercomparison Project Phase 6 (CMIP6) to analyze variables within the Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) framework. Focusing on two contrasting Shared Socioeconomic Pathways (SSPs) - SSP1-2.6 (low-warming scenario) and SSP5-8.5 (high-warming scenario) - we assess future impacts of climate-related factors on marine ecosystems across major oceanic regions. Under the high-warming SSP5-8.5 scenario, global ocean temperature rise, coupled with declining surface pH levels, nitrate concentrations, and plankton biomass/productivity, is evident. Regional reductions in plankton biomass/productivity, especially pronounced at higher latitudes, are observed in both SSP scenarios. Nutrient cycling emerges as a pivotal factor influencing plankton communities, particularly ammonium regulation in the Southern Ocean. This research emphasizes the urgent need to curb greenhouse gas emissions to mitigate global warmings profound effects on marine ecosystems.

Low levels of Al stimulate the aboveground growth of Davidia involucrata saplings

Davidia involucrata is a woody perennial and the only living species in the Genus Davidia. It is native to southern China where it holds cultural and scientific importance. However, D. involucrata is now an endangered species and its natural range includes low pH soils which are increasingly impacted by acid rain, nitrogen deposition and imbalanced nutrient cycling. The combination of these stresses also poses the additional risk of aluminum (Al) toxicity. Since the responses of D. involucrata to low pH and aluminum toxicity have not been investigated previously, a hydroponic experiment was conducted to examine the growth of one year old D. involucrata saplings after 50 d growth in a range of pH and Al conditions. Plant biomass, morphology, antioxidant enzyme activity, mineral concentrations and plant ecological strategy were compared at pH 5.8 and pH 4.0 without added Al (AlCl3) and in 0.1, 0.2 and 0.5 mM Al at pH 4.0. Our results showed that compared with pH 5.8, pH 4.0 (without added Al) not only inhibited root and shoot growth but also limited accumulation of nitrogen (N) and phosphorus (P) in leaves of D. involucrate. However, low Al concentrations (0.1 and 0.2 mM Al) at pH 4.0 partially restored the aboveground growth and leaf N concentrations, suggesting an alleviation of H+ toxicity by low Al concentrations. Compared with low Al concentrations, 0.5 mM Al treatment decreased plant growth and concentrations of N, P, and magnesium (Mg) in the leaves, which demonstrated the toxicity of high Al concentration. The results based on plant ecological strategy showed that D. involucrate decreased the competitiveness and favored its stress tolerance as pH changed from 5.8 to 4.0. Meanwhile, the competitiveness and stress tolerance of D. involucrata increased and decreased at low Al concentrations, respectively, and decreased and increased at high Al concentration, respectively. These trade-offs in ecological strategy were consistent with the responses of growth and antioxidant enzyme activity, reflecting a sensitive adaptation of D. involucrata to acid and Al stresses, which may aid in sustaining population dynamics. These findings are meaningful for understanding the population dynamics of D. involucrata in response to aluminum toxicity in acid soils.