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Phaeocystis globosa is a marine phytoplankton species that forms deleterious blooms in temperate and tropical waters. In some locations, “giant” colonies form, although the controls on its size are unknown. During a “giant” colony bloom, measurements were completed to characterize photosynthesis–irradiance relationships, nitrogen uptake kinetics, and nitrogen–irradiance relationships of P. globosa colonies to understand its growth characteristics and their relationship to colony size. The photosynthetic capacity (Fv/Fm) varied from 0.65 to 0.68 among colony sizes ranging from 3.0 to 11.0 mm, indicating that all colonial cells were physiologically robust. The maximum chl a‐specific photosynthetic rates (PmaxB$$ {P}_{\mathrm{max}}^B $$) ranged from 0.89 to 1.92 μg C · μg−1 chl · h−1, were maximal in the mid‐sized colonies (5.5–6.5 mm) and decreased with size. The relatively low PmaxB$$ {P}_{\mathrm{max}}^B $$ values may be related to the high cellular chl a of colonial cells and their acclimation to in situ irradiance. Nitrate Vmax$$ {V}_{\mathrm{max}} $$ and KS$$ {K}_S $$ values were greater than those of ammonium, although N affinity was greater for ammonium. No differences in light‐limited rates in either nitrate or ammonium uptake among colony sizes were observed, and no dark uptake occurred. Both ammonium and nitrate uptake showed a saturation response as a function of irradiance. While the driving forces for the formation of giant colonies remain unknown, their impacts on coastal systems are substantial and a further assessment of their growth is warranted. [ABSTRACT FROM AUTHOR]

The study investigated the interplay of factors influencing the occurrence of Uroglena sp. blooms in surface water, particularly during the spring season. While Uroglena sp. typically demonstrates a propensity for blooming during the spring season, diminished population density was documented, underscoring the influence of pertinent environmental factors. To study the determinants, surface water samples collected for 3 years were analyzed for general water quality parameters, coexisting microalgae species, and total bacteria. Key determinants were found to include the ratio of dissolved nitrogen to dissolved phosphorus (DN: DP), temperature, bacterial density, the presence of Dinobryon sp. (golden algae) and Microcystis sp. (cyanobacteria). The findings indicate that factors such as DN:DP ratios and temperature variations intricately modulate Uroglena sp. bloom by affecting microbial dynamics, notably competitive interactions. The findings of this study offer further scientific insight into addressing seasonal occurrences of fishy odors in water reservoirs, with particular relevance to the spring season. [ABSTRACT FROM AUTHOR]

Gelatin is a high molecular weight polypeptide that can be extracted not only from conventional sources such as hide, skins, and bones but also from the abundant collagen-rich by-products and wastes generated by industrial activities, such as poultry slaughterhouses. In this study, turkey feet were pretreated in a 3 M acetic acid solution and sequentially extracted in warm water at 55 °C, 65 °C, and 72 °C. The extracted gelatins were characterized based on their physicochemical properties, FTIR spectra, thermogravimetric and derivative analysis, molecular weight profile, bloom strength, and amino acid profile. Extraction yields ranged from 0.02 to 10.41%, totaling 15.14% after the three stages. Gelatin extracted in the first stage exhibited the most favorable characteristics, including a protein content of 77.58%, ash content of 15.13%, pH of 4.3, molecular weight distribution concentrated around 250 and 100 kDa, a bloom strength of 17.2 g, and amino acids (Hyp + Pro) content of 10.45%. The FTIR spectra indicated the presence of characteristic gelatin amides (A, B, I, II, and III) in all samples. Additionally, thermogravimetric analysis indicated that the degradation temperatures of the gelatins exceeded 300 °C. Overall, our findings suggest that turkey feet can be a promising raw material for gelatin extraction. This can minimize the waste of industrial by-products from turkey meat and generate extra income for processing industries, contributing to the concept of a circular economy. [ABSTRACT FROM AUTHOR]

Sampling was done over a year (December 2020–November 2021) to study the distribution and species composition of phytoplankton in the southwestern Caspian Sea. Sea water from various depths was collected along four transects: Lisar, Anzali, Sefidrood and Chaboksar, with a total of 12 stations. A comparison was then made with the data collected in 1996 to look at the long-term changes. The increase in sea water temperature and salinity, especially in summer, was observed in the present study, which was possibly due to global warming and climate change. Amongst 48 identified phytoplankton species, Bacillariophyta (80.0%) and Cyanophyta (11.0%) were dominant. Phytoplankton abundance was measured as 99,775 ± 30,200 cell L−1 on average. The highest abundance was a non-native species Pseudo-nitzschia seriata (H. Peragallo 1900) from Bacillariophyta with more than 17,000 cell L−1, followed by another toxic species Nodularia spumigena (Mertens ex Bornet and Flahault 1888) from Cyanophyta. The N. spumigena species had the highest abundance as 5,000,000 cell L−1 in July 2021 at the Anzali region. Nutrient increase of more than threefold in 2020–2021 has caused a sevenfold increase of chlorophyll-a as compared to that in 1996. The increases in nutrients levels, sea surface temperature (> 30 °C) and salinity are generally regarded as important factors to cause variations in phytoplankton abundance and composition. The sevenfold increase of phytoplankton abundance between 1996 and 2020–2021 and change of trophic state from oligotroph to mesotroph, indicated the increase of stress and pressure on the native phytoplankton community. [ABSTRACT FROM AUTHOR]

Teaching technical content in science and engineering requires the development of high-level competencies such as analytical and critical thinking skills, and is perceived by students as a difficult subject to understand. One way to help students learn this type of content is through the use of scaffolding, which dynamically regulates and adjusts learning according to the student’s needs. Although the use of scaffolding has already been applied in different educational contexts, so far there are no studies analysing its impact on students’ emotions and perception. In this paper we propose the LESCA system, which performs adaptive content feedback through scaffolding. The main hypothesis of this article is that the use of this tool together with teacher scaffolding improves the acquisition of content at higher cognitive levels and improves the student’s emotional state during learning. An experience has been carried out with 36 students of Industrial Electronics and Robotics Associate Degree with a pre-post design, where one group of students did not use the tool and another one did. The findings indicate that knowledge acquisition at the higher levels of Bloom’s taxonomy improved after the use of technological scaffolding and that this acquisition improved significantly when incorporating teacher scaffolding. On the other hand, students who performed the tasks with the system experienced significantly less anxiety and despair than students who did not use it. In addition, it has been found that students perceive teacher scaffolding to be significantly more useful than technological scaffolding.

The shelled pteropod Creseis acicula is a marine pelagic shellfish widely distributed from temperate to tropical seas around the world. From June to July 2020, a C. acicula bloom first happened in the Daya Bay, southern China, and its density reached the highest value (5600 ind. m−3) ever recorded around the world. However, few studies have investigated the responses of bacterial communities to the C. acicula bloom. In the present study, we examined the community profiles of three communities of bacteria including the free-living and particle-attached bacteria in the blooming and reference waters, and bacteria attached to the whole body and shell of C. acicula using a high-throughput sequencing method. The results indicated that the C. acicula bloom had a greater impact on particle-attached bacteria than free-living bacteria. Among the bloom-sensitive particle-attached bacteria, the predominant bacterial phyla were Pseudomonadota, Bacteroidota and Verrucomicrobiota in the blooming areas, whereas they were Actinomycetota and Planctomycetota in the reference areas. Specifically, fecal bacteria Haloferula and Halioglobus spp. were significantly enriched in the blooming waters and accumulated on C. acicula shells. Conversely, the significantly lower relative abundance of Nocardioides sp. in the blooming area and accumulated on the whole body of C. acicula indicated their attachment to particles consumed by C. acicula. Overall, our results suggested that the C. acicula bloom influenced marine bacteria, particularly particle-attached bacteria, by increasing (e.g. providing shells and feces) or decreasing (e.g. filter-feeding the suspended particles) the abundance of available substances. [ABSTRACT FROM AUTHOR]

Resilience, measured by the distribution of passage times between alternate states, indicates persistence of a state in stochastic dynamic systems such as blooms of cyanobacteria in lakes. We used high‐frequency datasets to compare the resilience of low and high states of phycocyanin, a pigment indicator of cyanobacteria, in Lake Mendota, Wisconsin, USA, for three growing seasons that ranged sevenfold in external phosphorus (P) load. Each year we observed 139–265 passage times across the unstable threshold that separated the low‐ from high‐phycocyanin states. Each sample of passage times is highly skewed with low median, larger mean, much larger SD, and wide tails extending to long lifetimes of a state. About 25% of events, whether low or high phycocyanin, lasted a day or more. Among these 3 years of contrasting external P load, there were no discernible differences in the resilience of either ecosystem state. We attribute this lack of contrast to the sustained recycling of P from sediments and the high stochasticity of phycocyanin in this lake. [ABSTRACT FROM AUTHOR]

Classical machine learning algorithms typically operate on unimodal data and hence it can analyze and make predictions based on data from a single source (modality). Whereas multimodal machine learning algorithm, learns from information across multiple modalities, such as text, images, audio, and sensor data. The paper leverages the functionalities of multimodal machine learning (ML) application for generating text from images. The proposed work presents an innovative multimodal algorithm that automates the creation of news articles from geo-tagged images by leveraging cutting-edge developments in machine learning, image captioning, and advanced text generation technologies. Employing a multimodal approach that integrates machine learning and transformer algorithms, such as visual geometry group network16 (VGGNet16), convolutional neural network (CNN) and a long short-term memory (LSTM) based system, the algorithm initiates by extracting the location from exchangeable image file format (Exif) data from the image. The features are extracted from the image and corresponding news headline is generated. The headlines are used for generating a comprehensive article with contemporary large language model (LLM). Further, the algorithm generates the news article big-science large openscience open-access multilingual language model (BLOOM). The algorithm was tested on real time photographs as well as images from the internet. In both the cases the news articles generated were validated with ROUGE and BULE score. The proposed work is found to be successful attempt in journalism field. [ABSTRACT FROM AUTHOR]

This study proposed a new method for homogenizing continuous casting blooms based on solidification simulation calculations and industrial tests. The text describes a theoretical analysis of the solidification route of a cast billet of high-carbon alloy steel (B300A) under different process conditions. It summarizes the changing law of different under-pressure process parameters and under-pressure efficiency. The text also presents a solution to the seriousness of center shrinkage defects in the continuous casting of a large square billet of high-carbon alloy steel with the synergistic control technology of mixed light and heavy mixing under pressure. The study indicates that the center carbon segregation index of a high carbon steel continuous casting billet is 1.05, with a carbon extreme difference of not more than 0.08% and a proportion of 98.4%. Additionally, the center shrinkage is not more than a 0.5 level with a proportion of 99.5%. Meanwhile, the internal quality of cast billets has been improved, allowing for the rolling of large-size bars with a low consolidation ratio. The pass rate for internal ultrasonic flaw detection using the GB/T4162A grade is now higher than 99.95%, significantly reducing process costs and improving production efficiency for continuous casting and rolling. [ABSTRACT FROM AUTHOR]

Cyanobacteria are oxygenic photosynthetic organisms which are found across many ecosystems, including freshwater and marine habitats. They are also found on natural and artificial surfaces. In this study, we cultured and characterise a novel cyanobacterium from the surfaces of foam microplastics of tropical coastal waters. We study the chemical ecology of this cyanobacterium, Sphaerothrix gracilis gen. et sp. nov., together with its potential to form harmful cyanobacterial blooms and bioremediation applications to combat plastic pollution. The genome of S. gracilis spanned 6.7 Mbp, with identification of antibiotic resistance, nitrogen-fixation, plastic-degrading and genes involved in harmful metabolite production. The transport of potentially harmful S. gracilis in coastal environments could have severe implications on human health and food security, especially in times of a cyanobacterial bloom. [ABSTRACT FROM AUTHOR]

Jellyfish (JF) are essential to marine ecosystems. However, JF that increases rapidly can have negative effects. On 3-4 August 2022, a significant JF (Lobonemoides robustus Stiasny, 1920) bloom was observed along Cox's Bazar coast (from Najdirartek to Sabrang) in Bangladesh. The goal of the current investigation was to identify the fatty acids (FAs) and amino acids (AAs) of L. robustus. The AAs were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, while the FAs were determined using a gas chromatographic system with a flame ionisation detector. The most prevalent AA was glycine. The most common FA was linoleic acid (C18:3) (0.43%), followed by myristic acid (0.12%), cis-9-oleic acid (0.18%), gamma-linolenic acid (0.24%), and heptadecanoic acid (0.29%). Based on its AA and FA contents, L. robustus can be a great candidate for the potentially sustainable manufacture of nutraceutical, cosmeceutical, and biomedical natural products to improve health and well-being. In addition, the edible L. robustus could be exported to other countries, thus way it can play a major role in achieving a blue economy. [ABSTRACT FROM AUTHOR]

Mesodinium rubrum is a kleptoplastidic ciliate that sequesters the chloroplasts and nuclei of cryptophyte algae to perform photosynthesis. Blooms of M. rubrum can cause red tides in coastal oceans worldwide. Such red tides are detectable by remote sensing, and studying M. rubrum pigments and optical properties is a crucial step toward characterizing its blooms using satellite observation. Previous studies have shown that M. rubrum photoacclimates, modifying its pigment content depending on irradiance. Using cultures at different irradiance levels, we observed that photoacclimation in M. rubrum closely resembles that of its cryptophyte prey Teleaulax amphioxeia , leading to substantial phenotypic variability. In both species, phycoerythrin 545 cellular concentrations increased 3-fold between the highest and lowest irradiance, suggesting a major role in photoacclimation. Absorption cross-section decreased, and pigment-specific absorption coefficients increased with irradiance at the peak absorption wavelengths of chlorophyll a and phycoerythrin 545. After assessing the variability of absorption properties in M. rubrum , we combined field measurements and high-resolution Sentinel-2 satellite images to estimate chlorophyll a concentration of a coastal red tide and document small-scale spatio-temporal features. This work provides an overview of pigment photoacclimation in a peculiar phytoplankter and suggests guidelines for future studies of M. rubrum blooms. [ABSTRACT FROM AUTHOR]

Abstract Resilience, measured by the distribution of passage times between alternate states, indicates persistence of a state in stochastic dynamic systems such as blooms of cyanobacteria in lakes. We used high‐frequency datasets to compare the resilience of low and high states of phycocyanin, a pigment indicator of cyanobacteria, in Lake Mendota, Wisconsin, USA, for three growing seasons that ranged sevenfold in external phosphorus (P) load. Each year we observed 139–265 passage times across the unstable threshold that separated the low‐ from high‐phycocyanin states. Each sample of passage times is highly skewed with low median, larger mean, much larger SD, and wide tails extending to long lifetimes of a state. About 25% of events, whether low or high phycocyanin, lasted a day or more. Among these 3 years of contrasting external P load, there were no discernible differences in the resilience of either ecosystem state. We attribute this lack of contrast to the sustained recycling of P from sediments and the high stochasticity of phycocyanin in this lake.

Historically, Physalis physalis massive stranding events have been infrequent and poorly documented. However, their occurrence can have significant impacts on human health and the stability of coastal ecosystems. In this study, we analyze a massive P. physalis stranding affected Cuba’s NW coast in December 2022. We counted all colonies during the massive event along ~ 3 km coast, within a 5 m stripe. Density, dimorphic form (left/right-handed), and colony size were quantified using 0.25 m2 quadrat placed every 50 m, 10 m from shoreline. Eighty-five people were stung, with 38 having strong allergic reactions, resulting in a health risk. Over ten thousand colonies were recorded, with the highest mean colony density (29.3 per m2) ever reported. The massive stranding coincided with the lowest Arctic Oscillation index (-2.59) in the past 11 years during December, which led to the emergence of northeasterly winds reaching speeds of up to 24 km/h. Wind direction and speed, coupled with the dominance of left-handed colonies (71.4%), suggest the North Atlantic Subtropical Gyre as a possible origin source of the bloom. The high prevalence of juvenile P. physalis colonies (68 %) likely aligns with the autumn breeding season in the northern hemisphere. The potential causes of P. physalis blooms are still poorly understood. Systematic monitoring of the distribution and abundance of this species should be a research priority considering the potential risk to human health and that the blooms could become more frequent in the Atlantic coasts, given climate change and increasing eutrophication of the oceans. Received: 10.08.2023 Accepted: 14.12.2023

Spring frosts are a limiting factor in sweet cherry production in central-southern Chile. Sweet cherry trees cv. ‘Regina’ and ‘Sweetheart’ were studied to evaluate the effect of foliar application of a biostimulant (Retard Cherry®) prior to leaf fall on the bloom delay, fruit set, fruit drop, yield and quality. Data were compared to a non-product control. The study was conducted in the Maule Region, Chile. Results showed that the use of Retard Cherry® delayed full bloom by 6-8 days between cultivars compared to the control; however, there was no delay in the harvest date. The climatic conditions favored high fruit set (37%-49%) and low fruit drop (63%-70%) between cultivars in both treatments. Regarding fruit quality, no differences in size, soluble solids concentration and color were observed with the product, but a decrease in firmness were observed for ‘Regina’. These results show that Retard Cherry® is an effective tool in delaying bloom, providing trees with more favorable climatic conditions for pollination and fruit set.

This study proposed a new method for homogenizing continuous casting blooms based on solidification simulation calculations and industrial tests. The text describes a theoretical analysis of the solidification route of a cast billet of high-carbon alloy steel (B300A) under different process conditions. It summarizes the changing law of different under-pressure process parameters and under-pressure efficiency. The text also presents a solution to the seriousness of center shrinkage defects in the continuous casting of a large square billet of high-carbon alloy steel with the synergistic control technology of mixed light and heavy mixing under pressure. The study indicates that the center carbon segregation index of a high carbon steel continuous casting billet is 1.05, with a carbon extreme difference of not more than 0.08% and a proportion of 98.4%. Additionally, the center shrinkage is not more than a 0.5 level with a proportion of 99.5%. Meanwhile, the internal quality of cast billets has been improved, allowing for the rolling of large-size bars with a low consolidation ratio. The pass rate for internal ultrasonic flaw detection using the GB/T4162A grade is now higher than 99.95%, significantly reducing process costs and improving production efficiency for continuous casting and rolling.

The jellyfish Pelagia noctiluca form extensive aggregations in the Mediterranean Sea that can exert top-down control on prey and cause mass-mortalities in fish farms. The description of extensive aggregations of P. noctiluca in the northeast Atlantic in 2007 coupled with a subsequent mortality event of farmed salmon in Northern Ireland prompted further investigation of the species in this region. We collected standardised P. noctiluca biomass from 1938 fisheries trawls over 11 years (2008–2018) covering ∼200,000 km2 of northeast Atlantic shelf seas. While a linear trend in P. noctiluca was not identified, the mean annual biomass exhibited significant fluctuations, with particularly elevated levels in 2009, 2013, 2014 and 2016 (0.05, 0.02, 0.01 and 0.02 kg ha−1, respectively). Mean biomass was higher in the northern (0.028 kg ha−1) and western portions (0.005 kg ha−1) of the study area compared to the southwestern (0.003 kg ha−1) and southeastern portions (0.001 kg ha−1). A binomial generalised linear mixed model of P. noctiluca biomass data indicated that higher P. noctiluca occurrence was driven by a positive Eastern Atlantic Pattern index (strongest effect), south-easterly winds, a negative North Atlantic Oscillation index and lower sea-surface temperatures (weakest effect). The fixed effects accounted for 36.81% of the variance in P. noctiluca occurrence data, while a random year effect further explained an additional 24.06% of the variance. These conditions may destabilise the European Slope Current in autumn-winter which promotes the transport of P. noctiluca from oceanic sources onto the northeast Atlantic shelf. Our findings represent a dramatic shift in our understanding of this species in the northeast Atlantic which may have significant ecological impacts, from predation on fish eggs and larvae to providing food for oceanic sunfish. • Pelagia noctiluca can form extensive aggregations in the northeast Atlantic. • Extensive aggregations covering∼40,000 km2 were found in 8 of 11 years. • P. noctiluca are more common to northeast Atlantic waters than previously thought. • P. noctiluca presence here is driven by hydroclimatic indices and wind patterns. • Ecological impacts include predation on fish eggs and food for ocean sunfish. [ABSTRACT FROM AUTHOR]

Karenia longicanalis , an athecate dinoflagellate, was first described during a bloom in Victoria Harbour (Hong Kong, China). This study confirms the presence of K. longicanalis as a bloom former in the eastern Pacific Ocean. Specimens were collected in March 2019 at three sampling stations in Acapulco Bay, Mexico. Water temperature, salinity, dissolved oxygen, and pH were measured in situ at the time of sample collection. Cell morphology was examined by optical and scanning electron microscopy. A molecular analysis based on the amplification of the large subunit (LSU) rDNA region revealed that the LSU sequences formed a monophyletic group with other GenBank sequences belonging to K. longicanalis. The resulting phylogeny demonstrates that Karenia is closely related to Asterodinium , Gertia , and Shimiella. The morphology of the specimens was consistent with previous descriptions. [ABSTRACT FROM AUTHOR]

• The study aimed to determine the evolutionary relationship of the green Noctiluca endosymbiont, Pedinomonas noctilucae , from the Gulf of Mannar, India. • The phylogenetic analysis showed that endosymbiotic algae Protoeuglena noctilucae belongs to an independent genus in the Marsupiomonadaceae family. • The green Noctiluca during its stationary phase changes to autotrophic nutrition to meet its energy needs and sustain population. The present investigation focused on studying the phylogenetic position of the green Noctiluca endosymbiont, Pedinomonas noctilucae , collected from the Gulf of Mannar, India. In this study, we re-examined the evolutionary position of this endosymbiotic algae using rbcL sequences. The phylogenetic analysis revealed that P. noctilucae is distantly related to the Pedinomonas species, and formed a monophyletic clade with Marsupiomandaceae. Based on the phylogenetic association of endosymbiont with Maruspiomonadales it was concluded that the endosymbiont belongs to an independent genus within the family Marsupiomonadaceae. At the site of the bloom, Noctiluca scintillans was found to exhibit a dense monospecific proliferation, with an average cell density of 27.l88 × 103 cells L−1. The investigation revealed that the green Noctiluca during its senescent phase primarily relied on autotrophic nutrition, which was confirmed by the presence of a high number of trophonts, vegetatively reproducing cells (1.45 × 103 cells L−1) and the absence of food vacuoles. [ABSTRACT FROM AUTHOR]

In this paper, we contemplate the dynamics of an aquatic system consisting of three interacting species, phytoplankton, zooplankton, and fish. We assume that the evading risk of fish predation induces fear in zooplankton species, which affects its growth dynamics radically. On the other hand, zooplankton develop an anti-predator defense by taking temporary refuge. Interestingly, the system potentially exhibits multi-stable configurations under identical ecological conditions by allowing different bifurcation scenarios, including multiple saddle–node and transcritical bifurcations with varying levels of nutrients, strength of phytoplankton toxicity, zooplankton refuge size and the cost of fear imposed by fish population. Further, by adding Gaussian white noise, we have extended the deterministic system to its stochastic version. We find that white noise appears to regulate the survival and extinction of model species. Comprehensive numerical simulations are consistent with mathematical results prognosticated by linear analysis. Overall, our study may provide a new insight into the mechanisms of emergence and mitigation of plankton blooms. • We study plankton-fish dynamics, including fear, refuge, and toxins. • The system exhibits multi-stability, abrupt transitions with toxicity, fear, etc. • Environmental forcing influences species persistence and extinction. • Estimated results offer insights into plankton bloom mechanisms. [ABSTRACT FROM AUTHOR]

The genus Phaeocystis is globally distributed, with blooms commonly occurring on continental shelves. This unusual phytoplankter has two major morphologies: solitary cells and cells embedded in a gelatinous matrix. Only colonies form blooms. Their large size (commonly 2 mm but up to 3 cm) and mucilaginous envelope allow the colonies to escape predation, but data are inconsistent as to whether colonies are grazed. Cultured Phaeocystis can also inhibit the growth of co-occurring phytoplankton or the feeding of potential grazers. Colonies and solitary cells use nitrate as a nitrogen source, although solitary cells can also grow on ammonium. Phaeocystis colonies might be a major contributor to carbon flux to depth, but in most cases, colonies are rapidly remineralized in the upper 300 m. The occurrence of large Phaeocystis blooms is often associated with environments with low and highly variable light and high nitrate levels, with Phaeocystis antarctica blooms being linked additionally to high iron availability. Emerging results indicate that different clones of Phaeocystis have substantial genetic plasticity, which may explain its appearance in a variety of environments. Given the evidence of Phaeocystis appearing in new systems, this trend will likely continue in the near future.

The gut microbiome plays important roles in host function and health. Core microbiomes have been described for different species, and imbalances in their composition, known as dysbiosis, are associated with pathology. Changes in the gut microbiome and dysbiosis are common in aging, possibly due to multi-tissue deterioration, which includes metabolic shifts, dysregulated immunity, and disrupted epithelial barriers. However, the characteristics of these changes, as reported in different studies, are varied and sometimes conflicting. Using clonal populations of Caenorhabditis elegans to highlight trends shared among individuals, we employed 16s rRNA gene sequencing, CFU counts and fluorescent imaging, identifying an Enterobacteriaceae bloom as a common denominator in aging animals. Experiments using Enterobacter hormaechei , a representative commensal, suggested that the Enterobacteriaceae bloom was facilitated by a decline in Sma/BMP immune signaling in aging animals and demonstrated its potential for exacerbating infection susceptibility. However, such detrimental effects were context-dependent, mitigated by competition with commensal communities, highlighting the latter as determinants of healthy versus unhealthy aging, depending on their ability to restrain opportunistic pathobionts., Competing Interests: Conflict of interest statement. The authors declare that they have no actual or apparent conflict of interest between authorship of this study and any other activities.