Modelling the interactions of soil microbes and nematodes

Nematology ◽  
2009 ◽  
Vol 11 (4) ◽  
pp. 619-629 ◽  
Author(s):  
Jouni K. Nieminen
Keyword(s):  
Dynamic Model ◽  
Material Flow ◽  
Model Performance ◽  
Food Chains ◽  
Food Web Structure ◽  
Soil Food Webs ◽  
Web Structure ◽  
Discrete Dynamic Model ◽  
Key Parameter

Abstract Six different soil food webs, assembled from a bacterium, a bacterial-feeding nematode, a fungus and a fungal-feeding nematode, were established in replicated laboratory microcosms. Glucose was supplied as the sole carbon source for the microbes. Biomasses of the organisms and the concentration of dissolved organic carbon (DOC) were measured ten times during 20 weeks. A discrete dynamic model based on the material flow between system components was fitted to the experimental data. Bacterial-based food chains were largely inactive in the absence of fungi, but mutual facilitation was observed in the systems with both fungus and bacterium. The population dynamics of a fungal-feeding nematode was adequately described by the models, but the model failed to describe DOC dynamics. The quality of fungal biomass appeared to be a key parameter in the system. Model performance was improved by letting fungal parameters vary with time and food web structure. Because fungal dynamics could not be explained by a trophic-dynamic model with rigid parameters, it is suggested that non-trophic effects of fungal-feeding nematodes on fungi may be more important in microcosms.

Food Chains and Omnivory

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Empirical Evidence ◽  
Food Chain ◽  
Stage Structure ◽  
Food Chains ◽  
Dependent Manner ◽  
Food Web Structure ◽  
Web Structure ◽  
Consumer Resource

This chapter extends the consumer–resource theory to include simple but common three-species modules behind the construction of whole food webs, with particular emphasis on food chains and omnivory. It first considers some common simple modular food web structures and whether the dynamics of subsystems can be seen using the framework laid out in previous chapters. Specifically, it asks when common food web structure increases or weakens the relative interaction strengths and/or when a food web structure modifies flux between consumers and resources in a density-dependent manner such that the food web tends to increase flux rates in some situations and decrease the coupling in other situations. The chapter also explores how stage structure can influence food chain stability before concluding with a review of empirical evidence on the dynamical implications of omnivory for food webs.

Impact of changing ice cover on pelagic productivity and food web structure in Disko Bay, West Greenland: a dynamic model approach

2003 ◽  
Vol 50 (1) ◽  
pp. 171-187 ◽  
Author(s):  
Anja Skjoldborg Hansen ◽  
Torkel Gissel Nielsen ◽  
Henrik Levinsen ◽  
Siz D. Madsen ◽  
T.Frede Thingstad ◽  
...  
Keyword(s):  
Food Web ◽  
Dynamic Model ◽  
Ice Cover ◽  
Food Web Structure ◽  
West Greenland ◽  
Web Structure ◽  
Model Approach

Effects of food-web structure on the quantity and the elemental quality of sedimenting material in shallow lakes

Hydrobiologia ◽  
2011 ◽  
Vol 679 (1) ◽  
pp. 251-266 ◽  
Author(s):  
Michael Danger ◽  
Béatrice Allard ◽  
Mohamad B. Arnous ◽  
Jean-François Carrias ◽  
Jacques Mériguet ◽  
...  
Keyword(s):  
Food Web ◽  
Shallow Lakes ◽  
Food Web Structure ◽  
Web Structure

scholarly journals Phagotrophic Protists and Their Associates: Evidence for Preferential Grazing in an Abiotically Driven Soil Ecosystem

2021 ◽  
Vol 9 (8) ◽  
pp. 1555
Author(s):  
Andrew R. Thompson ◽  
Andrea J. Roth-Monzón ◽  
Zachary T. Aanderud ◽  
Byron J. Adams
Keyword(s):  
Species Interactions ◽  
Abiotic Factors ◽  
Wall Structure ◽  
Dry Valleys ◽  
Food Web Structure ◽  
Soil Biodiversity ◽  
Soil Food Webs ◽  
Web Structure ◽  
Starting Point ◽  
Occurrence Patterns

The complex relationship between ecosystem function and soil food web structure is governed by species interactions, many of which remain unmapped. Phagotrophic protists structure soil food webs by grazing the microbiome, yet their involvement in intraguild competition, susceptibility to predator diversity, and grazing preferences are only vaguely known. These species-dependent interactions are contextualized by adjacent biotic and abiotic processes, and thus obfuscated by typically high soil biodiversity. Such questions may be investigated in the McMurdo Dry Valleys (MDV) of Antarctica because the physical environment strongly filters biodiversity and simplifies the influence of abiotic factors. To detect the potential interactions in the MDV, we analyzed the co-occurrence among shotgun metagenome sequences for associations suggestive of intraguild competition, predation, and preferential grazing. In order to control for confounding abiotic drivers, we tested co-occurrence patterns against various climatic and edaphic factors. Non-random co-occurrence between phagotrophic protists and other soil fauna was biotically driven, but we found no support for competition or predation. However, protists predominately associated with Proteobacteria and avoided Actinobacteria, suggesting grazing preferences were modulated by bacterial cell-wall structure and growth rate. Our study provides a critical starting-point for mapping protist interactions in native soils and highlights key trends for future targeted molecular and culture-based approaches.

scholarly journals Flooding affects food web structure and basal sources supporting fish guilds in a subtropical wetland and shallow lake

2021 ◽  
Author(s):  
Rodrigo Ferreira Bastos ◽  
Alexandre Miranda Garcia ◽  
Kirk O. Winemiller ◽  
Nelson Ferreira Fontoura
Keyword(s):  
Organic Matter ◽  
Food Web ◽  
Shallow Lake ◽  
Trophic Structure ◽  
Terrestrial Ecosystems ◽  
Spatial And Temporal Variation ◽  
Food Chains ◽  
Food Web Structure ◽  
Aquatic Animals ◽  
Web Structure

Abstract Aquatic ecosystems exchange nutrients and organic matter with surrounding terrestrial ecosystems, and floods import allochthonous material from riparian areas into fluvial systems. We surveyed food web components of a wetland and shallow lake in a subtropical coastal region of Brazil to examine how community trophic structure and the entrance of allochthonous material into the food web were affected by floods. Stable isotope analysis was performed for samples of terrestrial and aquatic basal production sources and aquatic animals to trace the origin of organic matter assimilated by aquatic animals and estimate vertical trophic positions and food chain length. Lake and wetland trophic structures were compared for cool/wet and warm/dry seasons. Food web structure was hypothesized to differ based on hydrology, with the more stable lake having greater food web complexity, and seasonal flooding resulting in greater allochthonous inputs to the aquatic food web. We compared spatial and temporal variation in assemblage trophic structure using an adapted isotopic ellipse approach that plots assemblage elements according to δ13C on the x-axis and estimated TP on the y-axis. Lake trophic structure was more complex with longer food chains compared to that of the wetland. A greater contribution from terrestrial resources to animal biomass was observed in the wetland during the cool/wet period, and food chains in both habitats tended to be longer during the cool/wet period. Findings supported the hypothesis of greater assimilation of allochthonous sources during floods and greater trophic complexity in the more hydrologically stable system.

scholarly journals How anthropogenic shifts in plant community composition alter soil food webs

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 4 ◽  
Author(s):  
Paul Kardol ◽  
Jonathan R. De Long
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Plant Community ◽  
Plant Communities ◽  
Ecosystem Functions ◽  
Plant Community Composition ◽  
Soil Food Web ◽  
Food Web Structure ◽  
Soil Food Webs ◽  
Web Structure

There are great concerns about the impacts of soil biodiversity loss on ecosystem functions and services such as nutrient cycling, food production, and carbon storage. A diverse community of soil organisms that together comprise a complex food web mediates such ecosystem functions and services. Recent advances have shed light on the key drivers of soil food web structure, but a conceptual integration is lacking. Here, we explore how human-induced changes in plant community composition influence soil food webs. We present a framework describing the mechanistic underpinnings of how shifts in plant litter and root traits and microclimatic variables impact on the diversity, structure, and function of the soil food web. We then illustrate our framework by discussing how shifts in plant communities resulting from land-use change, climatic change, and species invasions affect soil food web structure and functioning. We argue that unravelling the mechanistic links between plant community trait composition and soil food webs is essential to understanding the cascading effects of anthropogenic shifts in plant communities on ecosystem functions and services.

scholarly journals Nodule Detection with Convolutional Neural Network Using Apache Spark and GPU Frameworks

2021 ◽  
Vol 11 (6) ◽  
pp. 2838
Author(s):  
Nikitha Johnsirani Venkatesan ◽  
Dong Ryeol Shin ◽  
Choon Sung Nam
Keyword(s):  
Neural Network ◽  
Radiation Dose ◽  
Convolutional Neural Network ◽  
Model Performance ◽  
Performance Comparison ◽  
Apache Spark ◽  
Training Time ◽  
Learning Framework ◽  
Proposed Model

In the pharmaceutical field, early detection of lung nodules is indispensable for increasing patient survival. We can enhance the quality of the medical images by intensifying the radiation dose. High radiation dose provokes cancer, which forces experts to use limited radiation. Using abrupt radiation generates noise in CT scans. We propose an optimal Convolutional Neural Network model in which Gaussian noise is removed for better classification and increased training accuracy. Experimental demonstration on the LUNA16 dataset of size 160 GB shows that our proposed method exhibit superior results. Classification accuracy, specificity, sensitivity, Precision, Recall, F1 measurement, and area under the ROC curve (AUC) of the model performance are taken as evaluation metrics. We conducted a performance comparison of our proposed model on numerous platforms, like Apache Spark, GPU, and CPU, to depreciate the training time without compromising the accuracy percentage. Our results show that Apache Spark, integrated with a deep learning framework, is suitable for parallel training computation with high accuracy.

scholarly journals Modelling Exposure by Spraying Activities—Status and Future Needs

2021 ◽  
Vol 18 (15) ◽  
pp. 7737
Author(s):  
Stefan Hahn ◽  
Jessica Meyer ◽  
Michael Roitzsch ◽  
Christiaan Delmaar ◽  
Wolfgang Koch ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Model Performance ◽  
Relevant Information ◽  
Systematic Evaluation ◽  
Model Accuracy ◽  
Efficient Manner ◽  
User Perspective ◽  
Model Predictions ◽  
Spray Applications

Spray applications enable a uniform distribution of substances on surfaces in a highly efficient manner, and thus can be found at workplaces as well as in consumer environments. A systematic literature review on modelling exposure by spraying activities has been conducted and status and further needs have been discussed with experts at a symposium. This review summarizes the current knowledge about models and their level of conservatism and accuracy. We found that extraction of relevant information on model performance for spraying from published studies and interpretation of model accuracy proved to be challenging, as the studies often accounted for only a small part of potential spray applications. To achieve a better quality of exposure estimates in the future, more systematic evaluation of models is beneficial, taking into account a representative variety of spray equipment and application patterns. Model predictions could be improved by more accurate consideration of variation in spray equipment. Inter-model harmonization with regard to spray input parameters and appropriate grouping of spray exposure situations is recommended. From a user perspective, a platform or database with information on different spraying equipment and techniques and agreed standard parameters for specific spraying scenarios from different regulations may be useful.

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