Biological Indices Research Articles

Utilizing Data Mining Techniques in Geophysical and Biological Analysis for Assessing Environmental Risks

This study aimed to assess environmental risks using data extraction techniques. It focused on geophysical and biological factors and addressed the urgent need for effective risk management strategies to reduce soil erosion, water pollution, and air quality deterioration. A comprehensive dataset was created through the systematic collection of geophysical and biological data including temperature, soil composition, and biological abundance index. It used equipment such as satellite sensors and mountain transmitting stations. Various statistical tools used include decision trees and random forest algorithms. They were used to analyze data and identify important environmental risk factors. The results showed some interesting insights, revealing that the Neural Network has an accuracy of 95.5%, and the Random Forest algorithm predicts risk with an accuracy of 92.0%. It analyzed the classification of environmental hazard zones and identified high-risk zones, such as Zone A, which contains 10,000 people affected by erosion and Zone D, 20,000 people who were at risk from soil contamination. The study concludes that social media can significantly improve understanding and management of environmental risks. Additionally, it provides a useful framework for decision-makers and stakeholders to promote sustainable environmental practices.

Short-term exposure to okadaic acid induces behavioral and physiological responses in sea urchin (Strongylocentrotus intermedius)

Massive harmful algal blooms (HABs) have increased the risk of marine organisms encountering the dinoflagellate toxin, okadaic acid (OA). Strongylocentrotus intermedius, a globally significant benthic aquaculture species, has a large appetite for benthic algae. During red tide events, there is a high risk of red tide toxin accumulation. This study systematically evaluated the potential impact of short-term OA exposure on the behavior and physiological functions of juvenile S. intermedius. From typical (5 μg/L) to extreme OA concentrations (20 μg/L) during HAB outbreaks, OA exposure gradually inhibited a series of tube foot-related behaviors (sheltering, foraging, righting, and tube-foot tenacity). At OA concentrations during HAB outbreaks (5 μg/L), the tube foot function of S. intermedius was progressively inhibited. Further physiological indicator analyses revealed that the activity of antioxidants increased over a short period to prevent damage from reactive oxygen species induced by OA. However, OA ultimately suppressed the immune response of S. intermedius, leading to apoptosis. Although HAB-associated concentrations of OA (5 μg/L) did not induce a continuous increase in the integrated biological response index of S. intermedius, this study speculated that HABs pose a future risk to echinoderm species. Notably, principal component analysis results showed that OA exposure eventually induced significant changes in the production of O2-, malondialdehyde, and total glutathione, as well as in glutathione S-transferase activity and caspase-7, -8, and -9 levels. This study provides preliminary evidence of OA’s toxic effects on sea urchins and essential data for urgent risk assessments of algal toxin pollution in aquaculture during HABs.

Spatial patterns of hydroecological health in the semi-arid yellow river basin: Revelations from machine learning models

The ecosystem of semi-arid watersheds is influenced by a combination of natural climate factors, rainfall, and habitat destruction, resulting in complex mechanisms of spatial differentiation and evolution of water ecological health. Indicator selection in mainstream water ecological health assessment methods, such as the Index of Biotic Integrity (IBI), often relies on subjective reference point choices. This approach tends to overlook the comprehensive impacts and interactions among various environmental stressors. For watersheds significantly influenced by natural climatic factors, considerable uncertainties arise, leading to a lack of scientific justification for establishing water ecological health protection goals. In this study, the nonlinear capabilities of the random forest (RF) model were applied to reduce subjectivity in traditional water ecological health assessments and to more accurately reveal the emerging spatial differentiation patterns and underlying causes of water ecological health in the Wei River Basin (WRB), the largest typical semi-arid watershed of the Yellow River in China. Our findings indicate: (1) Traditional evaluation indices indicate that the overall water ecological health of the WRB is classified as sub-healthy (60 %). The core indicators include dominant species, total algal density, and the percentage of diatom density, with no significant spatial differentiation observed. (2) An improved water ecological health assessment method for semi-arid watersheds, based on the RF model, has been developed to replace traditional subjective judgment steps. This method establishes a complex multi-input–output response relationship (R2 > 0.85) between environmental stress indicators and the biological integrity index for the WRB. (3) The model results identify key driving factors affecting changes in water ecological health in semi-arid watersheds, with the sensitivity of the new model increasing nearly 11-fold compared to traditional IBI methods. (4) Following improvements, the water ecological health characteristics of the WRB exhibit significant spatial heterogeneity, with a higher dispersion coefficient (1.21), and demonstrate enhanced nonlinear response trends to climatic factors. The application of machine learning models indicates that traditional methods may underestimate the extent of ecological health degradation in watersheds and tend to oversimplify spatial heterogeneity characteristics.

Integrating external stressors in supervised machine learning algorithm achieves high accuracy to predict multi-species biological integrity index of aquaculture wastewater

Monitoring and predicting the environmental impact of wastewater is essential for sustainable aquaculture. The environmental DNA metabarcoding-integrated supervised machine learning (SML) algorithm is an alternative method for ecological quality assessment and prediction. However, the ecological integrity of aquaculture wastewater and available effective input features for prediction remain unclear. Here, we used the multispecies biological integrity index (Ms-IBI) to provide a detailed categorization, identifying over half of the samples (53.85 %) as highly impacted, emphasizing the urgency to address ecological degradation; Ms-IBI emerged as a reliable label for SML models. By condensing 410 effective indicators and integrating 25 core operational taxonomic unit features with external stressors, an accuracy of 0.78 and R2 of 0.96 was achieved. Utilizing only external stressors yielded a comparably good performance with fewer input features, obtaining an accuracy of 0.74 and an R2 of 0.91. The integration of external stressors in this study highlights a practical predictive method that meets the ecological quality requirements of aquaculture wastewater, aiding the reversal of global ecological decline.

Substantiation of the algorithm for identifying high-risk groups among the personnel of chemically hazardous facilities

Introduction. Studies of the impact of chemicals on the health of employees of chemical industry enterprises based on biomonitoring are an urgent medical and social problem. The article is devoted to the substantiation of the algorithm for examining personnel at chemically hazardous facilities to identify high-risk groups due to the effects of industrial poisons. Material and methods. The article presents an analysis of domestic and foreign scientific literature devoted to the problems of identifying high-risk groups among workers in chemical enterprises based on biomonitoring methods. Results. Identification of high-chemical risk groups among chemically hazardous facilities employees involves the following steps: assessment of the level of external chemical exposure, identification of priority pollutants, substantiation of the most informative bioenvironments and the time of analysis, determination of exposure/effect biomarkers, and clinical examination of personnel. Limitations. The proposed algorithm for identifying high-risk groups applies only to persons who are professionally in contact with hazardous chemicals. Discussion. The article presents an analysis of the scientific literature on the problem of identifying high-risk groups based on biomonitoring. Conclusion. In order to identify high-risk groups among the personnel of chemical enterprises, it is necessary to introduce the proposed algorithm and develop quantitative criteria for biomonitoring – biological maximum permissible concentrations (BEI) or biological exposure indices into the practice of toxicological and hygienic assessment of the health of workers.

Physiological traits and population dynamics of Schizothorax niger (Heckel, 1838): Insights from Dal Lake and the Jhelum River, Kashmir, Himalayan region.

This study examines the physicochemical characteristics, morphometric features, biometric growth parameters, biological indices, physiological parameters, and biochemical profiles of Schizothorax niger population. The physicochemical analysis revealed a maximum temperature of 12.93 ± 1.33°C and hardness of 156.53 ± 12.82 mg/L in Dal Lake, whereas the Jhelum River had a minimum level of 10.94 ± 1.12°C temperature and 128.31 ± 11.62 mg/L of hardness. Dal Lake had a neutral pH (7.5 ± 0.2) and lower dissolved oxygen (6.8 ± 0.4 mg/L) compared to the Jhelum River (pH 7.2 ± 0.3; dissolved oxygen 7.5 ± 0.5 mg/L). Morphometric analysis showed significant differences (p < 0.05) in fish length (Dal Lake: 18.4 ± 2.1 cm; the Jhelum River: 21.0 ± 1.8 cm) and weight (Dal Lake: 74.5 ± 9.8 g; the Jhelum River: 92.2 ± 7.4 g) between the sites. Biometric growth parameters demonstrated a positive allometric growth pattern, with Dal Lake having a steeper slope (b = 3.15) than the Jhelum River (b = 2.98). Biological indices revealed gender-based variations in the gonado-somatic index (GSI) and hepato-somatic index (HSI), with GSI being higher in Dal Lake (0.21 ± 0.02) and HSI in the Jhelum River (1.04 ± 0.09). Haematological and biochemical analyses showed significant differences in parameters such as haematocrit (Dal Lake: 29.2 ± 2.1%; the Jhelum River: 32.4 ± 1.8%), glucose (Dal Lake: 85.3 ± 5.4 mg/dL; the Jhelum River: 68.1 ± 4.2 mg/dL), and total protein (Dal Lake: 6.2 ± 0.4 g/dL; the Jhelum River: 5.8 ± 0.3 g/dL) between sites. These findings provide valuable insights into the physiological traits and population dynamics of S. niger, informing species-specific conservation strategies and ecosystem management practices.

Biological Characterization of Geo-Referenced Soil Samples from Major Rice-Growing Tracts of Southern Kerala

A survey was conducted from January to March 2023 to assess the soil biological fertility index across five agro-ecological units in the rice-growing belts of Southern Kerala. These units included Onattukara sandy loam (AEU 3), Kari soil (AEU 4), Pokkali soil (AEU 5), Southern laterites (AEU 8), and Midland laterites (AEU 9). The study was carried out in the College of Agriculture, Vellayani Thiruvananthapuram. The survey aimed to assess microbial activity and organic carbon content, thereby enhancing our understanding of the biological fertility across these diverse soil types. Twenty geo-referenced surface soil samples @ 0- 15 cm were collected in every AEU by prescribed method. The collected samples were subjected to the characterization of soil biological properties such as dehydrogenase activity, organic carbon, microbial biomass C, microbial biomass N and soil respiratory rate following the standard protocol. The findings showed that organic carbon in AEU 5 with the highest mean value (3.03 %), followed by AEU 4 (2.19 %), AEU 9 (2.01 %), AEU 8 (1.01 %), and AEU 3 (0.56 %). Dehydrogenase activity was highest in AEU 5 (682.54 µg TPF g-1 hr-1), followed by AEU 4, AEU 9, and AEU 8, and lowest in AEU 3 (76.71 µg TPF g-1 hr-1). AEU 5 exhibited the highest microbial biomass carbon and microbial biomass nitrogen activities, while AEU 8 showed the lowest. Soil respiration was highest in AEU 5 and lowest in AEU 3. Based on these soil microbiological indicators, soils were classified into three categories: low, medium, and high fertility. The Biological Fertility Index (BFI) scores indicated favorable conditions in AEU 4 and 5, moderate in AEU 9, and low in AEU 3 and 8. By establishing a comprehensive understanding of soil biological fertility across various agro-ecological units, the research aims to contribute to improved soil health and crop productivity in the region.

Fire and salvage logging increased recalcitrant soil organic matter and reduced soil functionality in Mediterranean pine forests.

Postfire management actions are used to mitigate damage caused by wildfires. Salvage logging, often employed to restore ecosystem functions in burnt stands, plays an essential role in reducing economic losses and the burn severity of future wildfires. However, its ecological implications for soil functionality still need to be understood, especially in the Mediterranean basin, which is prone to erosion and desertification. This study aimed to investigate the effects of fire on (i) soil organic matter (SOM) quality and composition using differential scanning calorimetry-thermogravimetry (DSC-TG) and solid-state nuclear magnetic resonance (13C CPMAS NMR) and (ii) phosphorus (P) forms using solid-state 31P NMR spectroscopy in a wildfire that affected 3200 ha in southeastern Spain in July 2017. One year after the fire, we monitored four Pinus halepensis Mill. stand categories based on soil burn severity (SBS): unburnt, low SBS, high SBS and high SBS areas with salvage logging (n=36, nine plots per SBS level). We collected soil samples and analysed soil pH, SOM content and SOM quality, along with biological activity indicators (carbon biomass, basal respiration, β-glucosidase, phosphatase activities) and P forms. We ran ANOVA statistical tests to identify significant differences in soil properties among SBS levels. We also established general linear regressions of thermo-recalcitrance values and aromaticity with biological soil quality indices to compare both techniques for detecting changes in SOM quality and composition. The results indicated that fire increased soil pH (up to 0.3), particularly in the plots with higher SBS levels. SOM decreased significantly with increasing SBS level (down to < 5 % at the high SBS level), with a shift from labile compounds (carbohydrates) to more recalcitrant ones (aromatics). Organic P forms were depleted, while orthophosphate levels rose, increasing the risk of irreversible fixation. This study also highlights that DSC-TG is a cost-effective technique for assessing SOM quality changes. Understanding these effects is essential for developing policies to conserve and restore fire-affected areas and to promote practices that enhance soil functionality and resilience.

Validation of physicochemical water quality results through cross-checking with biological indices

ABSTRACT Biological assessment of rivers is critical for evaluating ecosystem health, detecting ecological changes, validating physicochemical monitoring data, assessing the effectiveness of water treatment systems, conserving biodiversity, and guiding water resource management. In this study, the surface water quality of the Karkheh River basin was evaluated using the National Sanitation Foundation Water Quality Index (NSFWQI) and the Iranian Surface Water Quality Index (IRWQIsc) for qualitative analysis. For biological monitoring, the Biological Monitoring Working Party (BMWP) index, along with the Average Score per Taxon (ASPT) and the Hilsenhoff Biotic Index (HFBI), was employed to provide a comprehensive assessment. Water quality was analyzed across 18 sampling stations, revealing significant spatial variation. Upstream areas exhibited relatively good conditions, with NSFWQI and IRWQIsc values of 59 and 68, respectively. In contrast, downstream locations near urban and agricultural areas demonstrated poor water quality, with values of 27 and 33, respectively. Overall, approximately 70% of the river's length has been severely impacted, highlighting the need for targeted planning and management to mitigate pollution. The biological indices corroborated the physicochemical results, revealing severe ecological stress in polluted regions. The close alignment between the NSFWQI and biological indicators emphasizes the importance of a multifaceted approach in assessing aquatic health. Key factors contributing to the river's degradation include excessive water extraction, untreated wastewater discharge, and diminished self-purification capacity, particularly in downstream areas.

Effects of Substituting Fishmeal with Soy Protein Concentrate Supplemented with Essential Amino Acids in the Olive Flounder (Paralichthys olivaceus) Diet on the Expression of Genes Related to Growth, Stress, Immunity, and Digestive Enzyme.

This study identified the effects of substituting fishmeal (FM) with soy protein concentrate (SPC) supplemented with lysine and methionine in the olive flounder (Paralichthys olivaceus) diet on the expression of genes related to growth, stress, immunity, and digestion. Three experimental diets were prepared; the control diet (Con) contained 60% FM, and the experimental diets contained 25% (SPC25) and 50% (SPC50) FM replaced by SPC. After the 140-day feeding period, weight gain, specific growth rate, feed availability, biological indices, and chemical composition of the muscle were not significantly affected by the dietary treatments. The gene expression levels of growth-related genes (IGF, GFB-3), immune-related genes (IL-8 and caspase), and stress-related genes (SOD, GPX, PRX, TRX) were higher in Con fish than in those fed the SPC25 and SPC50 diets. Chymo-TRY2, TRY2, and TRY3 in the stomach of fish fed the SPC25 diet were higher than fish fed the Con or SPC50 diets. TRY2 and lipase of fish fed the SPC25 diet were higher than those of fish fed the other diets but TRY3 was not significantly affected by the treatments in the intestine. In conclusion, substituting 25% FM with SPC was the most effective diet for the expression of growth, immune, stress, and digestive enzyme genes.

Phytoplankton community structure in Tunda Island waters, Banten Indonesia as a bioindicator to measure water quality

Mining of sea sand in the water area of Tunda Island can result in changes in the quality of the aquatic environment. Phytoplankton may indicate changes due to their rapid reaction to external influences in water. This study aims to determine the water quality condition in Tunda Island waters using phytoplankton communities. The sample collection included 20 observation stations in Tunda Island waters, Banten province. The analyzed water samples had parameters of depth, temperature, pH, dissolved oxygen, total dissolved solids, salinity, nitrates, and phytoplankton communities. The results obtained by several quality water parameters still meet the quality standards except for nitrates. The composition of phytoplankton consists of 3 classes: Cyanophyceae, Bacillariophyceae, and Dinophyceae. Eight phytoplankton genera of the Bacillariophyceae class dominated during observation: Bacteriastrum sp., Chaetoceros sp., Hemiaulus sp., Lauderia sp., Nitzschia sp., Rhizosolenia sp., Skeletonema sp., Thalassiosira sp., and Thalassiotrix sp. The phytoplankton biological index describes the phytoplankton diversity index as moderate diversity, phytoplankton evenness is classified as unstable communities, and phytoplankton dominance is at a moderate condition. Variations within a phytoplankton group can reflect seasonal dynamics and the impact of changes in the aquatic environment.

Diversity Patterns of Plant Communities along an Elevational Gradient in Arid and Semi-Arid Mountain Ecosystems in China

Quantitative classification and ordination are instrumental in improving our understanding of plant community patterns and facilitating effective conservation efforts in national mountain ecosystems worldwide. However, there has been a lack of relevant research focused on arid and semi-arid mountain ecosystems. This study aims to address this gap by investigating the Ningxia Helan Mountain National Nature Reserve (located in Northwest China). We conducted a comprehensive study on the patterns of plant communities and their association with environmental factors across a broad elevation range from 1200 m a.s.l. to 2600 m a.s.l. Our findings revealed the presence of 121 angiosperm species across 41 families, with vegetation classified into six distinct groups through two-way indicator species analysis (TWINSPAN) along the elevational gradient. Notably, the communities of Ulmus, Prunus, and Stipa in the middle elevation range exhibited the highest Shannon–Wiener (SW) and Simpson (SN) diversity indices, and these indices followed a single-peak pattern with increasing elevation. Canonical correspondence analysis (CCA) further revealed six distinct yet interrelated plant communities, revealing elevation (ELE) and the biological aridity index (BK) as the most influential environmental factors influencing plant communities’ distribution. This understanding is critically important for biodiversity conservation and the management of ecosystems in arid and semi-arid mountain ecosystems.

Assessment of Ecological Status of Streams by Macrophyte Biological Index in Kahramanmaras Province (Turkiye)

Assessment of Ecological Status of Streams by Macrophyte Biological Index in Kahramanmaras Province (Turkiye)

Soil Microorganism Interactions under Biological Fumigations Compared with Chemical Fumigation.

Biological fumigation, a potential alternative to chemical fumigation, shows a wide range of prospective applications. In this study, we carried out biological fumigation experiments to evaluate its effect on alleviating consecutive cropping problems (CRPs) when compared with chemical fumigation. We designed five treatments, namely, CR (no treatment), LN (chemical fumigation with lime nitrogen), Ta (fumigation with marigold), Ra (fumigation with radish), and Br (fumigation with mustard), for soils for replanting eggplant and measured the crop's growth status, soil bacterial and fungal communities, and soil physicochemical properties. The results showed that the Br and Ra treatments formed similar microbial communities, while the Ta treatment formed unique microbial communities. The genera Olpidiomycota and Rozellomycota could be used as indicator species for the transformation process of soil microbial communities after the Br and Ta treatments, respectively. When compared with the CR and LN treatments, the soil's physicochemical properties were optimized under the Br treatment, and the soil organic matter content increased by 64.26% and 79.22%, respectively. Moreover, under the Br treatment, the soil's biological properties enhanced the bacterial and fungal alpha diversity, and the saprotrophic fungi increased with the depletion of pathotrophic fungi, while some specific probiotic microorganisms (such as Olpidiomycota, Microascales, Bacillus, etc.) were significantly enriched. In contrast, under the Ta treatment, soil nutrient levels decreased and the soil's biological indices deteriorated, whereas the bacterial diversity decreased and the pathogenic fungi increased. Among these three biological fumigation methods, the Br pre-treatment was the best way to alleviate the crop's CRPs and may be a good substitute for chemical fumigation in some situations. However, the Ta treatment also had some risks, such as the loss of land quality and reduced productivity.

Biomass inputs drive agronomic management impacts on soil health

Numerous conservation and regeneration practices are recognized as effective strategies in the management of soil health (SH), a critical factor for ensuring the sustainability of food production systems. Despite their acknowledged importance, the multifaceted impacts of these practices often lead to confounding effects, and reliance on generic categorization of agronomic practices often falls short in portraying the drivers of SH. We advocate for a paradigm shift from a label-centric approach to one rooted in processes. Our study underscores the pivotal role of aboveground biomass cycling as an indicator for assessing the potential of agronomic management practices to instigate shifts in carbon balances, and, consequently SH. Drawing on soil physical, biological, and chemical SH data from three Uruguayan long-term experiments on Pampas region Mollisols we (i) present quantitative evidence of the importance of evaluating SH through biomass inputs, and (ii) illustrate the applicability of the proposed framework for evaluating different scenarios of land management for the region. Management-induced variations in aboveground biomass inputs accounted for 50 % of the observed changes in a composite soil's physical and biological SH index and helped explain the inconsistent effect of management practices. Raising the SH Index by ten points required an increase in biomass inputs of over 50 Mg ha⁻¹. Based on this concept, substantial enhancements in SH can be made by narrowing yield gaps and intensifying cropping sequences over many years. The benefits of practices such as increased crop diversification, integration of perennial and cover crops, or reduced tillage in promoting SH depend in part on their ability to augment biomass production. This nuanced understanding underscores the importance of aligning agronomic strategies with the fundamental processes driving SH dynamics.

Long-term rice-crayfish farming alters soil dissolved organic carbon quality and biodegradability by regulating microbial metabolism and iron oxidation

The biodegradability of dissolved organic carbon (DOC) is a crucial process in the migration and transformation of soil organic carbon (SOC), and play a vital role in the global soil carbon (C) cycle. Although the significance of DOC in SOC transportation and microbial utilization is widely acknowledged, the impact of long-term rice-crayfish (RC) farming on the content, quality, and biodegradability of DOC in paddy soils, as well as regulatory mechanisms involved, remains unclear. To address this gap, a space-for-time method was employed to investigate the effects of different RC farming durations (1-, 5-, 10-, 15-, and 20- years) on the quality and biodegradability of DOC, as well as their relationship with soil microbial metabolism and minerals in this study. The results revealed that continuous RC farming increased the soil DOC content, but reduced DOC biodegradability. Specifically, after 20 years of continuous RC farming, the DOC content increased by 52.7% compared to the initial year, whereas the DOC biodegradability decreased by 63.4%. Analysis using three-dimensional fluorescence and ultraviolet spectroscopy demonstrated that continuous RC farming resulted in a decrease in the relative abundance of humus-like fractions, humification, and aromaticity indexes in DOC, but increased the relative abundance of protein-like fractions, biological, and fluorescence index, indicating that long-term RC farming promoted the simple depolymerization of the molecular structure of DOC. Continuous RC farming increased the activity of hydrolase involved in soil nitrogen (N) and phosphorus (P) cycles and oxidase, but decreasing the hydrolase C/N and C/P acquisition ratios; moreover, it also stimulated an increase in soil iron oxides and exchangeable calcium content. Structural equation modeling suggests that soil hydrolases and iron oxides are the primary drivers of DOC quality change, with DOC biodegradability being driven solely by soil iron oxides and not regulated by DOC quality. In conclusion, long-term RC farming promotes the catalytic decomposition of DOC aromatic substances and the production of DOC protein-like components by increasing soil oxidase activity and decreasing the hydrolase C/N acquisition ratio; these processes collectively contribute to the simple depolymerization of DOC molecular structure. Additionally, long-term RC farming induced legacy effects of soil iron oxides and enhanced chemical protection role leading to reduced DOC biodegradability. These findings suggested that long-term RC farming may reduce the rapid turnover and loss of DOC, providing a negative feedback on climate warming.

Effect of Long-Term Fertilization Practices on the Stability of Soil Organic Matter in the Northeast Black Soil Region in China

Soil organic matter (SOM) is an important carbon pool in terrestrial ecosystems and plays a key role in soil functions. Nevertheless, the effects of fertilization practices on the physical, chemical, biological, and comprehensive stability of SOM are still unclear. We carried out a long-term field experiment in the northeast black soil region in China with four different fertilization practices: no fertilizer (CK), single chemical fertilizer (NPK), chemical fertilizer + straw (NPKJ), and chemical fertilizer + organic manure (NPKM). The content of particulate organic matter (POM) and mineral-associated organic matter (MAOM), compound composition of SOM, carbon mineralization characteristics, active soil organic matter (ASOM), and inert soil organic matter (ISOM) were tested. The results showed that the application of fertilizers significantly increased the contents of POM and MAOM to 2.59–4.65 g kg−1 and 32.69–34.65 g kg−1 (p &lt; 0.05), but decreased the MAOM/POM values by 37.8–42.4%, indicating reduced the physical stability of SOM. Fertilization practices increased the contents of aromatic, nitrogen-containing compounds and decreased the oxygen compounds of SOM, representing enhancement of the chemical stability. The contents of ASOM and ISOM increased in fertilization practices, while the biological stability index (BSI) under the NPKJ and NPKM treatments was lower than the CK treatment, suggesting that the biological stability decreased under the manure and straw application. In addition, the comprehensive stability of SOM increased by 26–116% through a reduction in the physical and biological stability, coupled with an increase in the chemical stability. Collectively, our study demonstrated that the application of manure and straw enhanced both the comprehensive stability and content of SOM and reduced the physical and biological stabilities while increasing the chemical stability, which made the largest contribution to the comprehensive stability.

The Spatiotemporal Variation and Ecological Evaluation of Macroinvertebrate Functional Feeding Groups in the Upper Yellow River.

Against the backdrop of hydropower development in the upper Yellow River, comprehending the spatiotemporal variation and ecological evaluation of macroinvertebrate functional feeding groups (FFGs) is paramount for the conservation and restoration of aquatic biological resources in watersheds. Detailed surveys of macroinvertebrates were conducted in the gorge and plain areas of the upper Yellow River in July 2022 and March, May, and October 2023, culminating in the identification of 65 taxonomic units (genus or species) spanning 4 phyla, 14 orders, and 35 families. Of these, 41 taxonomic units were discovered in the gorge areas and 57 in the plain areas. Among the FFGs of macroinvertebrates in the upper Yellow River, collector-gatherers were overwhelmingly dominant, followed by scrapers, collector-filterers, predators, and shredders. Concerning river section types, dominant species in the gorge areas included Gammarus sp., Limnodrilus hoffmeisteri, and Polypedilum sp. among collector-gatherers, while in the plain areas, dominant species included Ecdyonurus sp. among scrapers, Hydropsyche sp. among collector-filterers, and Gammarus sp., Limnodrilus hoffmeisteri, and Chironomus sp. among collector-gatherers. A Mantel test revealed that dissolved oxygen, conductivity, and orthophosphate were the primary environmental factors affecting the FFGs of macroinvertebrates in the upper Yellow River, with variations observed in their effects across different months. The evaluation results of the Hilsenhoff Biological Index and Shannon-Wiener Index indicate that the water quality of the upper Yellow River is at a moderate level. An assessment of the upper Yellow River ecosystem using FFG parameters demonstrated that macroinvertebrate biomass progressively increased from upstream (gorge areas) to downstream (plain areas) spatially, accompanied by increasing habitat stability, with cascade hydropower development identified as a key factor impacting habitat stability. These findings provide pertinent data and a theoretical foundation for the protection of aquatic biological resources and watershed management in the upper Yellow River.

Effects on the productivity, haematological indices, and carcass quality of Nile tilapia reared at different stocking densities in a hybrid biofloc-RAS

The performance at varied over-stocking of Oreochromis niloticus was evaluated in a hybrid biofloc-recirculating aquaculture system (HBR) viz., 150 fish/m3 (HBR-SD150), 200 fish/m3 (HBR-SD200), 250 fish/m3 (HBR- SD250), and 300 fish/m3 (HBR- SD300) along with 150 fish/m3 (BFT-SD150) and 150 fish/m3 (RAS-SD150) each maintained in triplicate. Tapioca flour was used to maintain the carbon to nitrogen ratio of 15:1 within the HBR and BFT units throughout the experimental period of 120 days. At the conclusion of the experiment, assessments were made of productivity, biological and haematological indices; and proximate composition of the fish and the floc. Evern though significantly higher productivity was observed in HBR-SD200, a quadratic regression model applied to the productivity as a function of stocking density {Stocking density (fish/m3) = −21.008 × 2 + 532.15× - 3090.2, R2 = 0.6929} and the optimum productivity for O. niloticus (Nile tilapia) found to be 13.2 Kg/m3 at 229.89 fish/m3. Notably, HBR-SD150 groups exhibited significantly higher levels of haematological indices including NBT. The Proximate composition of the floc revealed that a significantly higher quantity of protein and ash was found in HBR-SD150 and HBR-SD300, respectively. There was no significant difference in carcass composition of Nile tilapia across the treatments except for that of crude protein levels. Profitability analysis demonstrated that low stocking density groups achieved greater profits than high stocking density HBR and control. The findings of present study indicate that the maximum production that can be accomplished from the HBR culture system is 13.2 Kg/m3 at a density of 229.89 fish/m3 without affecting the growth, immunity, and survival of Nile tilapia.

Hydromorphological pressure explains the status of macrophytes and phytoplankton less effectively than eutrophication but contributes to water quality deterioration

Hydromorphological alterations are among the human-induced pressures that must be considered when assessing the ecological status of aquatic ecosystems. We investigated the effects of hydromorphological pressures on the ecological status of lowland lakes in Poland, focusing particularly on macrophyte and phytoplankton conditions. The analysis was based on biological, hydromorphological, and physicochemical data collected from 30 lowland lakes. Almost all biological and physicochemical indices correlated significantly (Spearman's |R|>0.5) with the hydromorphological index LHMS_PL. Using the variation partitioning method, we found that hydromorphological pressures explained only a small proportion (5.5%) of the variability in ecological status assessed using macrophytes. These pressures had no direct effects on the ecological status assessed using phytoplankton. The shared effects of physicochemistry and hydromorphology explained a large proportion of the variability in ecological status indices based on both phytoplankton and macrophytes. The results demonstrated that in the analysed lakes, hydromorphological alterations were usually accompanied by increased nutrient concentrations. This finding indicates that physical alterations may affect lake biological assemblages not only directly but also indirectly by reducing the ecosystem's natural buffering capacity, thereby promoting the eutrophication process.