SEARCH · PubMed Health

Results for “Ecosystem”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed1996

A Chemoautotrophically Based Cave Ecosystem

Microbial mats discovered in a ground-water ecosystem in southern Romania contain chemoautotrophic bacteria that fix inorganic carbon, using hydrogen sulfide as an energy source. Analysis of stable carbon and nitrogen isotopes showed that this chemoautotrophic production is the food base for 48 species of cave-adapted terrestrial and aquatic invertebrates, 33 of which are endemic to this ecosystem. This is the only cave ecosystem known to be supported by in situ autotrophic production, and it contains the only terrestrial community known to be chemoautotrophically based.

Journal Article↗

PubMed2026

The Baltic Sea: A Unique and Sensitive Ecosystem.

The Baltic Sea is a young, semi-enclosed brackish ecosystem shaped by postglacial history; restricted exchange with the North Sea; and strong gradients in salinity, temperature, and oxygen. These conditions have produced a species-poor but highly productive and ecologically important system. This review synthesizes evidence that Baltic populations persist not only through phenotypic plasticity but also through rapid evolutionary change, local adaptation, hybridization, and demographic history. Population genomic studies reveal sharp genetic differentiation between Baltic and Atlantic populations in many taxa, often across the Danish Straits, and fine-scale structuring within the Baltic itself. Case studies of eelgrass, bladderwrack, blue mussels, Baltic clam, cod, flounder, and herring illustrate how clonality, hybrid swarm formation, reproductive isolation, and habitat-specific selection shape resilience and vulnerability. Rapid warming, hypoxia, eutrophication, overfishing, and low functional redundancy increase ecosystem sensitivity. Long-term resilience will depend on protecting locally adapted populations and integrating genomic knowledge into ecosystem-based management and conservation.

Journal Article↗

PubMed2026

SCMO: a deep learning model integrating the single-cell resolution TME ecosystem and multi-omics for survival prediction in CRC patients.

BACKGROUND: Colorectal cancer (CRC) remains a leading cause of global cancer mortality, highlighting the need for precise survival prediction to guide clinical decisions. Although tissue-level multi-omics is widely utilized for survival prediction, its limited resolution cannot capture tumor heterogeneity. Single-cell RNA sequencing (scRNA-seq) enables dissection of the tumor microenvironment (TME) at cellular resolution, supporting personalized prognostic assessment. METHODS: We collected 213 CRC scRNA-seq samples and established a CRC-specific TME atlas comprising 339,060 cells. Using this atlas as a reference, we deconvolved bulk RNA-seq data from TCGA-CRC cohort with the EcoTyper algorithm to reconstruct TME features. Clinical, genomic, and transcriptomic data were obtained from the Xena platform; microbial data were sourced from the BIC database. We integrated TME and multi-omics features through a self-normalizing neural network to construct a deep learning model (single-cell resolution TME ecosystem with multi-omics data [SCMO]) for survival prediction. To enhance interpretability, we utilized the Integrated Gradients algorithm and spatial transcriptomic data to analyze multi-omics and TME features. We performed anticancer drug screening with tumor necrosis factor receptor-associated protein 1 (TRAP1), a critical feature according to the Integrated Gradients algorithm, as a potential target. RESULTS: We identified 13 survival-related TME features from the CRC-specific atlas: 12 cell states and one multi-cellular ecosystem. SCMO, which combined TME and multi-omics features, improved survival prediction and outperformed existing methods, achieving a concordance index of 0.762. The SCMO demonstrated robust performance for long-term predictions, achieving areas under the curve (AUCs) of 0.752, 0.772, and 0.869 for 1-, 3-, and 5-year predictions in the training set, with corresponding test set AUCs of 0.639, 0.756, and 0.772. TME features from the SCMO model revealed that ecosystem density increased with CRC malignancy. Multi-omics features included TRAP1 as a potential drug target. Drug screening identified saikosaponin A as a novel TRAP1 inhibitor, and its anticancer activity was validated in vitro. We developed SCMO-Lite, a simplified model incorporating 12 high-attribution-weight multi-omics features, which demonstrated robust risk stratification. CONCLUSIONS: SCMO combines analytical precision with biological interpretability, offering novel insights for oncology survival prediction.

Humans↗

PubMed1975

Environmental fate and biodegradability of benzene derivatives as studied in a model aquatic ecosystem.

A model aquatic ecosystem is devised for studying relatively volatile organic compounds and simulating direct discharge of chemical wastes into aquatic ecosystems. Six simple benzene derivatives (aniline, anisole, benzoic acid, chlorobenzene, nitrobenzene, and phthalic anhydride) and other important specialty chemicals: hexachlorobenzene, pentachlorophenol, 2,6-diethylaniline, and 3,5,6-trichloro-2-pyridinol were also chosen for study of environmental behavior and fate in the model aquatic ecosystem. Quantitative relationships of the intrinsic molecular properties of the environmental micropollutants with biological responses are established, e.g., water solubility, partition coefficient, pi constant, sigma constant, ecological magnification, biodegradability index, and comparative detoxication mechanisms, respectively. Water solubility, pi constant, and sigma constant are the most significant factors and control the biological responses of the food chain members. Water solubility and pi constant control the degree of bioaccumulation, and sigma constant limits the metabolism of the xenobiotics via microsomal detoxication enzymes. These highly significant correlations should be useful for predicting environmental fate of organic chemicals.

Animals↗

PubMed1984

Evaluation of mirex, photomirex and chlordecone in the terrestrial aquatic laboratory model ecosystem.

The insecticides mirex and chlordecone and the mirex photodegradation product, photomirex, were evaluated in a terrestrial aquatic laboratory model ecosystem. Although chlordecone was to some extent degraded during the 33 days, neither mirex nor photomirex produced identifiable levels of decomposition products in the water or in any of the organisms of the model ecosystem. All three compounds accumulated significantly in the organisms of the model ecosystem, with chlordecone the least bioaccumulative and photomirex the most bioaccumulative.

Animals↗

PubMed2006

Whole-system nutrient enrichment increases secondary production in a detritus-based ecosystem.

Although the effects of nutrient enrichment on consumer-resource dynamics are relatively well studied in ecosystems based on living plants, little is known about the manner in which enrichment influences the dynamics and productivity of consumers and resources in detritus-based ecosystems. Because nutrients can stimulate loss of carbon at the base of detrital food webs, effects on higher consumers may be fundamentally different than what is expected for living-plant-based food webs in which nutrients typically increase basal carbon. We experimentally enriched a detritus-based headwater stream for two years to examine the effects of nutrient-induced changes at the base of the food web on higher metazoan (predominantly invertebrate) consumers. Our paired-catchment design was aimed at quantifying organic matter and invertebrate dynamics in the enriched stream and an adjacent reference stream for two years prior to enrichment and two years during enrichment. Enrichment had a strong negative effect on standing crop of leaf litter, but no apparent effect on that of fine benthic organic matter. Despite large nutrient-induced reductions in the quantity of leaf litter, invertebrate secondary production during the enrichment was the highest ever reported for headwater streams at this Long Term Ecological Research site and was 1.2-3.3 times higher than predicted based on 15 years of data from these streams. Abundance, biomass, and secondary production of invertebrate consumers increased significantly in response to enrichment, and the response was greater among taxa with larval life spans < or = 1 yr than among those with larval life spans >1 yr. Production of invertebrate predators closely tracked the increased production of their prey. The response of invertebrates was largely habitat-specific with little effect of enrichment on food webs inhabiting bedrock outcrops. Our results demonstrate that positive nutrient-induced changes to food quality likely override negative changes to food quantity for consumers during the initial years of enrichment of detritus-based stream ecosystems. Longer-term enrichment may impact consumers through eventual reductions in the quantity of detritus.

Animals↗

PubMed2001

Effects of field exposure to diazinon on small mammals inhabiting a semienclosed prairie grassland ecosystem. I. Ecological and reproductive effects.

The widespread use of cholinesterase-inhibiting pesticides in the environment presents increasing concerns about their effects on human, wildlife, and ecosystem health. As a group, these pesticides are generally highly toxic and have great potential for negatively affecting nontarget organisms. Small mammals have proven to be ideal biomonitors of environmental contaminants, and were used here to test for possible effects of a widely used cholinesterase-inhibiting insecticide, diazinon, in a natural field setting. Using 12 0.1-ha terrestrial mesocosms, we examined the effects of low-level diazinon exposure on the small mammal communities inhabiting semienclosed grassland ecosystems. Our primary objective was to test the hypothesis that diazinon, applied at two different recommended label application rates, would not cause any observable adverse ecological or reproductive effects on small mammal populations and communities. Experimental small mammal communities consisting of Sigmodon hispidus, Microtus ochrogaster, Reithrodontomys fulvescens, and Mus musculus were stocked at natural densities and sex ratios inside empty mesocosms. Diazinon 4E was applied at two different maximum recommended label application rates, 0.56 kg a.i./ha (1x) and 4.5 kg a.i./ha (8x), and controls remained unsprayed, with four enclosures (replicates) per treatment. Two 30-d trials were run during peak rodent breeding seasons and enclosures were sampled on days 2, 16, and 30 of each trial. Recovery of small mammals was not significantly different among treatments, although fewer animals were recovered from the diazinon-exposed enclosures in both trials. Analysis of trapping data suggested that the normally strong competitive relationship between Sigmodon and Microtus may be altered by the pesticide, favoring Microtus in the diazinon-exposed enclosures. Incidence of reproductive condition was found to be reduced 20 to 80% and 33 to 100% in diazinon-exposed males and females, respectively. Reproductive productivity, including percentage of pregnant females and of females giving birth, was significantly reduced in diazinon-exposed animals. Percentage of pregnant females ranged from 13.6 to 43.5% in diazinon-exposed animals compared to 40 to 80% for control animals, and percentage of females giving birth ranged from 0 to 17% in diazinon-exposed animals compared to 22 to 50% for control animals. Generally, the effects found in this study suggest that diazinon was relatively persistent in the sprayed enclosures and that oral routes of exposure (consumption of dead and dying arthropods, grooming) may have been important. Ecological relationships and reproduction in both herbivorous and omnivorous mammals were negatively impacted by diazinon exposure. Overall, ecological relationships in the enclosed prairie grassland ecosystem were disrupted by diazinon, probably through a combination of sublethal effects, particularly reproductive effects, impacting individuals and their populations. This suggests that negative impacts on populations and community structure and function may persist longer than diazinon persists in the environment.

Animals↗

PubMed2003

Complexity in natural microbial ecosystems: the Guerrero Negro experience.

The goal of this project is to describe and understand the organismal composition, structure, and physiology of microbial ecosystems from hypersaline environments. One collection of such ecosystems occurs at North America's largest saltworks, the Exportadora de Sal, in Guerrero Negro, Baja California Sur. There, seawater flows through a series of evaporative basins with an increase in salinity until saturation is reached and halite crystallization begins. Several of these ponds are lined with thick (10 cm) microbial mats that have received some biological study. To determine the nature and extent of diversity of the microbial organisms that constitute these ecosystems, we are conducting a phylogenetic analysis using molecular approaches, based on cloning and sequencing of small subunit (SSU) rRNA genes (16S for Bacteria and Archaea, 18S for Eukarya). In addition, we report preliminary results on the microbial composition of a laminated community that occurs in a crystallized gypsum-halite matrix in near-saturated salt water. Exposure of the interior of these large (kilogram) wet, endoevaporite crystals reveals a multitude of colors: layers of yellow, green, pink, and purple microbiota. To date, analyses of these two environments indicate the ubiquitous dominance of uncultured organisms of phylogenetic kinds not generally thought to be associated with hypersaline environments.

Bacteria↗

PubMed2000

FORUM: The Relationship of Ecosystem Management to NEPA and Its Goals.

/ The National Environmental Policy Act of 1969 (NEPA) was intended to promote a systematic, comprehensive, interdisciplinary approach to planning and decisionmaking, including the integration of the natural and social sciences and the design arts. NEPA critics have cited three key shortcomings in its implementation: (1) a lack of engagement with the NEPA process early in the planning process through interdisciplinary collaboration; (2) a lack of rigorous science and the incorporation of ecological principles and techniques; and (3) a lack of emphasis on the Act's substantive goals and objectives. In recent years and independent of NEPA, a policy of ecosystem management has been developed, which represents a fundamental change from a fragmented, incremental planning and management approach to a holistic, comprehensive, interdisciplinary land and resource management effort. We postulate that by incorporating ecosystem management principles in their planning and decisionmaking, federal agencies can address the shortcomings in NEPA implementation and move closer to NEPA's intent. A case analysis of EISs prepared by the USDA Forest Service before and after adopting an ecosystem management approach supports our hypothesis.

Journal Article↗

PubMed1980

[2 rules on the life cycle of trematodes in the ecosystem].

Rule I: The more advanced in its primary evolution a life cycle is, the greater the participation of the animal component in it is. Parallel to that, most often the direct effect of the non-living component of the ecosystem on the cycle running is decreased. Rule II: In the majority of secondarily evolved life cycles of trematodes the following occurred in comparison with their initial life cycle: a) either a decrease of the direct effect of the non-living component of the ecosystem on the cycle running; b) or a decrease of the participation of the animal component of the ecosystem in the cycle; c) or most often a decrease of both together.

Animals↗

PubMed2002

Diversity of microfungi in the phylloplane of plants growing in a Mediterranean ecosystem.

Mediterranean ecosystems have not been investigated as natural habitats for microorganisms in general, and microfungi in particular. Plants harvested in "Serra da Arrábida" (38 degrees 27' N, 9 degrees 02' W), a Mediterranean ecosystem in Portugal, were analyzed for the filamentous microfungi inhabiting their surface. Two field locations with distinct climatic characteristics were studied: 'Fonte do Veado' (38 degrees 28'50" N, 9 degrees 0'17" W; 300 m elevation) located on the northern slope, and 'Mata do Solitário' (38 degrees 27'55" N, 8 degrees 59'35" W; 50 m elevation), on the southern slope. From Veado zone, leaf samples yielded a total of 3,049 isolates, ranging from 317 to 1,328/sample (mean = 762). The number of species/sample ranged from 12 to 24. From Solitario zone, leaf samples yielded a total of 1,337 isolates, ranging from 189 to 528/sample (mean = 334). The number of species/sample, in this case, ranged from 10 to 17. Veado zone showed a wider range of species. The fungal species more frequently isolated from both zones (Aureobasidium pullulans (De Bary) Arnaud, Cladosporium cladosporioides (Fresen.) De Vries, C. sphaerospermum Penzig and Alternaria alternata (Fr.) Keissler) were found in all plant samples and represents 80% (Veado) and 85% (Solitario) of the total isolates.

Ecosystem↗

PubMed1996

Chemical and physical context for life in terrestrial hydrothermal systems: chemical reactors for the early development of life and hydrothermal ecosystems.

The diversity of terrestrial hot spring systems, resulting from the large scale coupled transfer of heat and mass in the Earth's crust, maximizes opportunities for evolving ecosystems by the continuous supply of nutrients (P, N, C, S) together with the metals (e.g. K, Mg, Mo, Zn) essential to biogenesis. Cyclic, evaporative micro-environments are common, and potentially catalytic mineral surfaces are also continually created through rock alteration and mineral deposition in and around hot springs. These dynamical systems constitute highly interactive, open, chemical environments capable of establishing complex biochemical microreactors. Volcanic collapse settings on oceanic islands, provide a highly dynamic scenario for the initiation of life and development of diverse ecosystems at the earliest stages of development of the Earth's crust.

Archaea↗

PubMedDate not supplied

Importance and difficulties of research on metal speciation in the aquatic ecosystem: an ecologist's viewpoint.

Post-war research on the role of heavy metals in the environment was stimulated by a new sensitivity towards nature, the increasing impact of human activities on the environment, continuous progress in analytical chemistry and the development of radioecology. Nowadays, very low concentrations of total metal can be quantified in the various compartments of the ecosystem (e.g. water, sediment, suspended particles, plants and animals), and the physical and chemical forms of the metal identified. A current difficulty is how to evaluate the role of the various metal forms in the natural ecosystem. The major issues to be tackled are: variations over time of metal species in relation to the influence of environmental variables; the fact that the availability of the metal varies with the plant and animal species; the ability of the organism to select the metals and their forms; the influence of suspended particles and chelating substances on metal uptake, detoxification strategies and synergic and antagonistic effects. The advantages and disadvantages of monitoring using bioaccumulator organisms are discussed.

Animals↗

PubMed1996

Design and construction of model stream ecosystems.

A series of 12 outdoor model stream mesocosms was designed to evaluate the effects of chemicals and mixtures on the biota in stream ecosystems. An integrated design plan incorporated physical, chemical, and biological factors as well as the specific experimental objectives and effects parameters to be evaluated. Analysis of biological assemblages such as macroinvertebrates and periphyton in the model stream mesocosms demonstrated the presence of diverse and sensitive taxa. These model stream mesocosms also included the ability to evaluate responses of sentinel fish species such as Pimephales promelas and Lepomis macrochirus as well as macrophytes. The design and construction of the stream are discussed in detail and a brief description of a typical experimental protocol is provided. Experiments, to date, have spanned 14-30 days pretreatment "colonization" with 30 days of treatment and 15 days of posttreatment observation. Precision and accuracy of test chemical delivery to the stream have been excellent and the overall experimental design has been useful for delivering threshold toxicity concentrations and evaluating ecosystem potency for the chemicals tested.

Analysis of Variance↗

PubMed1996

Diagnosing ecosystem health.

In the past five years, international symposia, new journals, emergence of several new societies, redirection of environmental programs, and funding for new degree programs have heralded the birth of the science of "Ecosystem Health and Medicine." This paper develops the fundamental theory of diagnosis. As a medical science, a process for systematically developing an ecosystem "patient" history (anamnesis) is required. Taking a history implies that certain types of information, that are specifiable in advance, should be the focus of the preliminary examination. This paper identifies conceptual aspects of the preliminary examination and provides an initial anamnesis form. The primary emphasis of this paper is to present and illustrate a rigorous formal mathematical procedure for using the data to carry out the deductive process of health determination. As the process is carried out, deductive elimination of spurious signs and diseases will imply the types of detailed studies which are required to identify the combination of diseases (disease complex) occurring in a given ecological system.

Diagnosis↗

PubMed1997

Ecosystem recovery following selenium contamination in a freshwater reservoir.

Belews Lake, North Carolina, was contaminated by selenium in wastewater released from a coal-fired electric generating facility during 1974-1985. Selenium bioaccumulated in aquatic food chains and caused severe reproductive failure and teratogenic deformities in fish. Beginning in 1986, the electric utility company changed its ash disposal practices and selenium-laden wastewater no longer entered the lake. A survey of selenium present in the water, sediments, benthic invertebrates, fish, and aquatic birds was conducted in 1996. Concentrations were compared to pre-1986 levels to determine how much change occurred during the decade since selenium inputs stopped. The data were also examined using a hazard assessment protocol to determine if ecosystem-level hazards to fish and aquatic birds had changed as well. Results reveal that waterborne selenium fell from a peak of 20 micrograms/liter before 1986, to < 1 microgram/liter in 1996; concentrations in biota were 85-95% lower in 1996. Hazard ratings indicate that high hazard existed prior to 1986 and that moderate hazard is still present, primarily due to selenium in the sediment-detrital food pathway. Concentrations of selenium in sediments have fallen by about 65-75%, but remain sufficiently elevated (1-4 micrograms/g) to contaminate benthic food organisms of fish and aquatic birds. Field evidence confirmed the validity of the hazard ratings. Developmental abnormalities in young fish indicate that selenium-induced teratogenesis and reproductive impairment are occurring. Moreover, the concentrations of selenium in benthic food organisms are sufficient to cause mortality in young bluegill and other centrarchids because of Winter Stress Syndrome. At the ecosystem level, recovery has been slow. Toxic effects are still evident 10 years after selenium inputs were stopped. The sediment-associated selenium will likely continue to be a significant hazard to fish and aquatic birds for years.

Animals↗

PubMed1998

Culture and human agro-ecosystem dynamics: the Tsembaga of New Guinea.

In his classic work, Pigs for the Ancestors, Roy Rappaport proposed that the ritual cycle of the Tsembaga was a mechanism to regulate human population growth and prevent the degradation of the Tsembaga ecosystem. Rappaport provided detailed ethnographic and ecological information to support his claim, but many aspects of Rappaport's model were subsequently criticised. Several simulation models of the Tsembaga ecosystem were constructed to test Rappaport's hypothesis (Shantzis & Behrens, 1973; Foin & Davis, 1984) and evaluate possible alternatives (e.g. Foin & Davis, 1987). The basic conclusions were that it was possible to develop models supporting Rappaport's hypothesis but they were extremely sensitive to parameter choices, and other simpler population control mechanisms might be more likely (Buchbinder, 1977; Foin & Davis, 1987). In this paper, a much simpler dynamical system model for a slash-and-burn agricultural system is developed and applied to the Tsembaga system. By analysing the structure of the model for different physical and socioeconomic conditions, sources of instability and possible stabilising mechanisms are identified. The model indicates that behavioral plasticity (ability to modify behavior over a wide range of behavioral options, quickly and easily) is a fundamental source of instability which is strong enough to nullify more direct stabilising influences such as malnutrition and disease. This suggests that the only possible mechanism to counter to this fundamentally destabilising force may be cultural, i.e. the ritual cycle. Finally, a condition is outlined for which the ritual cycle will produce (local) stability.

Behavior↗

PubMed2002

Consequences of plant-herbivore coevolution on the dynamics and functioning of ecosystems.

The potential consequences of plant-herbivore coevolution for ecosystem functioning are investigated using a simple nutrient-limited ecosystem model in which plant and herbivore traits are subject to adaptive dynamics. Although the ecological model is very simple and always reaches a stable equilibrium in the absence of evolution, coevolution can generate a great diversity of dynamical behaviors. The evolutionary dynamics can lead to a stable equilibrium. If the evolution of plants is fast enough, certain values of the trade-off parameters lead to complex evolutionary cycles bounded by physiological constraints. The dynamical behavior of the model is very different when the dynamics of inorganic nutrient is ignored and plant competition is modeled by a logistic growth function. This emphasizes the importance of including explicit nutrient dynamics in studies of plant-herbivore coevolution.

Adaptation, Biological↗