The effect of disturbance and carrying capacity
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PROVIDER: PRJEB46802 | ENA |
REPOSITORIES: ENA
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Project description:Changes in species' trophic niches due to habitat degradation can affect intra- and interspecific competition, with implications for biodiversity persistence. Difficulties of measuring species' interactions in the field limit our comprehension of competition outcomes along disturbance gradients. Thus, information on how habitat degradation can destabilize food webs is scarce, hindering predictions regarding responses of multispecies systems to environmental changes. Seagrass ecosystems are undergoing degradation. We address effects of Posidonia oceanica coverage reduction on the trophic organization of a macroinvertebrate community in the Tyrrhenian Sea (Italy), hypothesizing increased trophic generalism, niche overlap among species and thus competition and decreased community stability due to degraded conditions. Census data, isotopic analysis, and Bayesian mixing models were used to quantify the trophic niches of three abundant invertebrate species, and intra- and interspecific isotopic and resource-use similarity across locations differing in seagrass coverage. This allowed the computation of (1) competition strength, with respect to each other and remaining less abundant species and (2) habitat carrying capacity. To explore effects of the spatial scale on the interactions, we considered both individual locations and the entire study area ("'meadow scale"). We observed that community stability and habitat carrying capacity decreased as P. oceanica coverage declined, whereas niche width, similarity of resource use and interspecific competition strength between species increased. Competition was stronger, and stability lower, at the meadow scale than at the location scale. Indirect effects of competition and the spatial compartmentalization of species interactions increased stability. Results emphasized the importance of trophic niche modifications for understanding effects of habitat loss on biodiversity persistence. Calculation of competition coefficients based on isotopic distances is a promising tool for describing competitive interactions in real communities, potentially extendible to any subset of ecological niche axes for which specimens' positions and pairwise distances can be obtained.
| S-EPMC5552933 | biostudies-literature
Project description:Backpack carrying impacts lung function in healthy children but the effect in children with cystic fibrosis (CF) is unknown.Three backpack positions were tested: no backpack (NB), a 12.5% body-weight backpack carried bilaterally (BB) or unilaterally (UB), at rest and during a 10 minute walk. Primary outcome was forced vital capacity (FVC). Secondary outcomes included comparison of cardio-respiratory variables within and between groups.Nine children with CF (13.3±2.6 years; FEV1 66±22%) and 18 healthy children (13.8±1.8 years; FEV1 107±30%) were included. FVC was reduced with UB compared to NB (68.5±23.3% vs 72.1±24.3%, p = 0.024) in children with CF. FEV1, MIP and MEP decreased more with UB in children with CF than in healthy peers. Increases in VO2, VCO2 and minute ventilation with UB were greater in the CF group during walking.Unilateral backpack wearing affects FVC in children with CF and requires greater cardio-respiratory adjustments compared to healthy peers.
| S-EPMC5942831 | biostudies-literature
Project description:Understanding how periodical disturbances affect the community assembly processes is vital for predicting temporal dynamics in microbial communities. However, the effect of dilutions as disturbances are poorly understood. We used a marine bacterial community to investigate the effect of disturbance (+/−) and carrying capacity (high/low) over 50 days in a dispersal-limited 2 × 2 factorial study in triplicates, with a crossover in the disturbance regime between microcosms halfway in the experiment. We modelled the rate of change in community composition between replicates and used this rate to quantify selection and ecological drift. The disturbed communities increased in Bray–Curtis similarity with 0.011 ± 0.0045 (Period 1) and 0.0092 ± 0.0080 day−1 (Period 2), indicating that selection dominated community assembly. The undisturbed communities decreased in similarity at a rate of −0.015 ± 0.0038 day−1 in Period 1 and were stable in Period 2 at 0.00050 ± 0.0040 day−1, suggesting drift structured community assembly. Interestingly, carrying capacity had minor effects on community dynamics. This study is the first to show that stochastic effects are suppressed by periodical disturbances resulting in exponential growth periods due to density-independent biomass loss and resource input. The increased contribution of selection as a response to disturbances implies that ecosystem prediction is achievable.
| S-EPMC9723678 | biostudies-literature
Project description:BACKGROUND: Host-plasmid interactions have been discussed largely in terms of the influences of plasmids, whereas the contributions of variations in host genomes to host interactions with foreign DNA remain unclear. A strain with a so-called "clean genome" (i.e., MDS42) of reduced genome size has recently been generated from the wild-type strain MG1655, a commonly used host strain. A quantitative evaluation of the influence of plasmid burdens in these two Escherichia coli strains can not only provide an understanding of how a reduced genome responds to foreign DNA but also offer insights into the proper application of these strains. RESULTS: The decreases in growth caused by the cost of carrying foreign DNA were similar for the wild-type and clean-genome strains. A negative correlation between the growth rate and the total amount of exogenous DNA was observed in both strains, but a better theoretical fit with a higher statistical significance was found for the strain with the clean genome. Compared to the wild-type strain, the clean-genome strain exhibited a reduced carrying capacity for exogenous DNA, which was largely attributed to its ability to restrict the replication of foreign DNA. A tendency to allocate energy and resources toward gene expression, but not DNA replication, was observed in the strain with the clean genome. CONCLUSIONS: The possession of a clean genome constrained the plasmid copy number to a wild-type-equivalent load. The results indicate that the wild-type strain possesses a greater tolerance for foreign DNA, as in endosymbiosis, and that the use of strains with clean genomes will be favorable in the applications that require precise control and theoretical prediction.
| S-EPMC4021254 | biostudies-other
Project description:Trillions of plastic debris fragments are floating at sea, presenting a substantial surface area for microbial colonization. Numerous cultivation-independent surveys have characterized plastic-associated microbial biofilms, however, quantitative studies addressing microbial carbon biomass are lacking. Our confocal laser scanning microscopy data show that early biofilm development on polyethylene, polypropylene, polystyrene, and glass substrates displayed variable cell size, abundance, and carbon biomass, whereas these parameters stabilized in mature biofilms. Unexpectedly, plastic substrates presented lower volume proportions of photosynthetic cells after 8 weeks, compared to glass. Early biofilms displayed the highest proportions of diatoms, which could influence the vertical transport of plastic debris. In total, conservative estimates suggest 2.1 × 1021 to 3.4 × 1021 cells, corresponding to about 1% of the microbial cells in the ocean surface microlayer (1.5 × 103 to 1.1 × 104 tons of carbon biomass), inhabit plastic debris globally. As an unnatural addition to sea surface waters, the large quantity of cells and biomass carried by plastic debris has the potential to impact biodiversity, autochthonous ecological functions, and biogeochemical cycles within the ocean.
| S-EPMC7852875 | biostudies-literature
Project description:With the rapid development of China's social economy, the phenomenon of unbalanced regional economic development is increasingly obvious. The shortage of water resources in northwest China is an important constraint to local development. The study on the water resources carrying capacity of the Zhuanglang River Basin plays an important role in the development of local economy; thus, we evaluate the water resources situation of Zhuanglang River Basin by using hydrology-related calculation method, combining with field investigation, visiting relevant departments, and referring to relevant data. Meanwhile, the water resources carrying capacity of 3 counties and 12 townships in the Zhuanglang River Basin in the current year are studied and analyzed based on methods such as fuzzy comprehensive evaluation model and quantitative calculation. Results indicate that the carrying capacity of water resources in Zhuanglang river basin can mostly meet the needs of township, but it is necessary to further optimize the water resources carrying capacity of the Zhuanglang River Basin from the four systems of water resources, society, economy, and ecology in the future. Besides, the results of quantitative calculation show that the maximum economic scale that water resources can withstand in most areas of the Zhuanglang River Basin is the overall well-off level, that is, the per capita domestic water is 80L/(d· person), and the per capita GDP is 10000 yuan/person. But there is still a certain gap to achieve the level, when the people are well-off in an all-round way, the two indexes are correspondently raised to 120L/(d· person), and the per capita GDP is 30,000 yuan/person.
| S-EPMC9023428 | biostudies-literature
Project description:Quantifying the ecological carrying capacity has emerged as a crucial factor for maintaining ecosystem stability for sustainable development in vulnerable eco-regions. Here, we propose a new framework for ecological carrying capacity quantification suitable for vulnerable eco-regions. We applied this framework to calculate the ecological carrying capacity of Inner Mongolia from 1987-2015 and used a geographical detector to identify the driving factors behind spatial heterogeneity. Our results revealed the following. (1) The above-ground net primary production (ANPP) required to support the ecosystem service of soil conservation (ANPPSC) decreased from northeast to southwest, whereas the distribution pattern of ANPP required to support the ecosystem service of sand fixation (ANPPSF) exhibited a contrary trend. The average annual ANPP required to support the ecosystem service of natural regeneration (ANPPNR) in Inner Mongolia from 1987 to 2015 was 101.27 gCm-2year-1, revealing a similar spatial distribution with ANPP. (2) The total ecological carrying capacity of Inner Mongolian grassland was 78.52 million sheep unit hm-2. The regions with insufficient provisioning service capability accounted for 4.18% of the total area, primarily concentrated in the east and northwest. (3) The average optimal livestock number for grasslands in Inner Mongolia was 1.59 sheep unit hm-2 from 1987-2015, ranging from 0.77 to 1.69 sheep unit hm-2 across different zones. The average ecological carrying capacity of the cold temperate humid, medium-temperate arid, and warm temperate semi-humid regions was less than 1.08 sheep unit m-2, suggesting a need to prohibit grazing in these areas. (4) The primary influencing factors affecting ecological carrying capacity distribution were normalized difference vegetation index (NDVI), precipitation, and soil type. The framework developed herein can help identify sustainable development potential from the ecosystem service perspective and effectively contribute to decision-making in grassland ecosystem management.
| S-EPMC10664909 | biostudies-literature
Project description:Optical multiplex barcode systems have been significantly boosting the throughput of scientific discovery. A high volume of barcodes can be made from combinations of distinct spectral bands and intensity levels. However, the practical capacity often reaches a ceiling due to the overlaps of signal frequencies or intensities when massive information is written on individual carriers. In this paper, we built super-capacity information-carrying systems by tuning vibrational signals into octal numeral intensities in multiple bands of Raman-silent regions. This novel approach experimentally yielded the largest capacity of distinct optical barcodes to date. The experiments of encoding ASCII and Unicode systems to write and read languages indicate that the Raman coding method provides a new strategy for super-capacity data storage. In addition, multiplex screening of a cell-binding ligand was implemented to demonstrate the feasibility of this technology for fast and in situ high-throughput bio-discovery. These information-carrying systems may open new scenarios for the development of high-throughput screening, diagnostics and data storage.
| S-EPMC8157647 | biostudies-literature
Project description:Environmental variability greatly influences the eco-evolutionary dynamics of a population, i.e. it affects how its size and composition evolve. Here, we study a well-mixed population of finite and fluctuating size whose growth is limited by a randomly switching carrying capacity. This models the environmental fluctuations between states of resources abundance and scarcity. The population consists of two strains, one growing slightly faster than the other, competing under two scenarios: one in which competition is solely for resources, and one in which the slow (cooperating) strain produces a public good (PG) that benefits also the fast (free-riding) strain. We investigate how the coupling of demographic and environmental (external) noise affects the population's eco-evolutionary dynamics. By analytical and computational means, we study the correlations between the population size and its composition, and discuss the social-dilemma-like 'eco-evolutionary game' characterizing the PG production. We determine in what conditions it is best to produce a PG; when cooperating is beneficial but outcompeted by free riding, and when the PG production is detrimental for cooperators. Within a linear noise approximation to populations of varying size, we also accurately analyse the coupled effects of demographic and environmental noise on the size distribution.
| S-EPMC6127162 | biostudies-literature
Project description:If land resources are forced to withstand greater populations than they are able to withstand, irreversible damage to the land resources system will happen in a specific region. This challenge highlights the urgency of appropriately evaluating the land resources carrying capacity (LRCC). A proper level of the capacity can ensure that land resources demands imposed by human activities are at a reasonable level. There is a need for a proper evaluation method for assessing LRCC. This study presents a new evaluation method from a load-carrier perspective for assessing LRCC by examining the relationships between the pressure caused by human activities and the supply capacity of land resources. In developing this method, a land resources system is determined by two primary components, namely carrier and load. The compositions of carrier and load are determined by applying the theory of multifunctional land use. A case demonstration is conducted to show the application of the method. The main findings can be drawn from this study as follows. Firstly, a "load-carrier" perspective method is requested for evaluating the regional LRCC, and it is effective in obtaining the value of LRCC in the demonstration case. Secondly, the composition of land resources carriers and loads embodied in the load-carrier perspective method is determined by using the theory of multifunctional land use. Thirdly, the case results suggest that seven regions are overloaded in LRCC and the other two regions are approaching the limitation of LRCC among nine county-level administration regions in Chongqing. This study contributes to the development of literature in the field of LRCC. The application of the "load-carrier" perspective method can help local governments in the case study regions make policies to ensure that land resources demands imposed by human activities are under control at a reasonable level.
| S-EPMC9102171 | biostudies-literature