scholarly journals Data paper: FoRAGE (Functional Responses from Around the Globe in all Ecosystems) database: a compilation of functional responses for consumers and parasitoids

2018 ◽  
Author(s):  
Stella F. Uiterwaal ◽  
Ian T. Lagerstrom ◽  
Shelby R. Lyon ◽  
John P. DeLong
Keyword(s):  
Prey Density ◽  
Type Ii ◽  
Functional Responses ◽  
Food Web Structure ◽  
Experimental Conditions ◽  
Data Set ◽  
Global Database ◽  
Web Structure ◽  
Resource Interactions ◽  
Consumer Resource

Functional responses - the relationships between consumer foraging rate and resource (prey) density - provide key insights into consumer-resource interactions and predation mechanics while also being a major contributor to population dynamics and food web structure. We present a global database of standardized functional response parameters extracted from the published literature. We refit the functional responses with a Type II model using standardized methods and report the fitted parameters along with data on experimental conditions, consumer and resource taxonomy and type, as well as the habitat and dimensionality of the foraging interaction. The consumer and resource species covered here are taxonomically diverse, from protozoans filtering algae to wasps parasitizing moth larvae to wolves hunting moose. The FoRAGE database (doi:10.5063/F17H1GTQ) is a living data set that will be updated periodically as new functional responses are published.

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.

scholarly journals Food-web structure in low- and high-dimensional trophic niche spaces

2010 ◽  
Vol 7 (53) ◽  
pp. 1735-1743 ◽  
Author(s):  
Axel G. Rossberg ◽  
Åke Brännström ◽  
Ulf Dieckmann
Keyword(s):  
Food Web ◽  
Trophic Niche ◽  
High Dimensional ◽  
Niche Space ◽  
Food Web Structure ◽  
One Dimensional ◽  
Evolutionary Diversification ◽  
Web Structure ◽  
Higher Dimensional ◽  
Consumer Resource

A question central to modelling and, ultimately, managing food webs concerns the dimensionality of trophic niche space, that is, the number of independent traits relevant for determining consumer–resource links. Food-web topologies can often be interpreted by assuming resource traits to be specified by points along a line and each consumer's diet to be given by resources contained in an interval on this line. This phenomenon, called intervality, has been known for 30 years and is widely acknowledged to indicate that trophic niche space is close to one-dimensional. We show that the degrees of intervality observed in nature can be reproduced in arbitrary-dimensional trophic niche spaces, provided that the processes of evolutionary diversification and adaptation are taken into account. Contrary to expectations, intervality is least pronounced at intermediate dimensions and steadily improves towards lower- and higher-dimensional trophic niche spaces.

scholarly journals Toward a Solution of the “Peruvian Puzzle”: Pelagic Food-Web Structure and Trophic Interactions in the Northern Humboldt Current Upwelling System Off Peru

2022 ◽  
Vol 8 ◽  
Author(s):  
Jana C. Massing ◽  
Anna Schukat ◽  
Holger Auel ◽  
Dominik Auch ◽  
Leila Kittu ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Interactions ◽  
Food Web Structure ◽  
Data Set ◽  
Humboldt Current ◽  
Upwelling System ◽  
Web Structure ◽  
Pelagic Food Web ◽  
Vertical Range ◽  
Spatial Coverage

The northern Humboldt Current upwelling system (HCS) belongs to the most productive marine ecosystems, providing five to eight times higher fisheries landings per unit area than other coastal upwelling systems. To solve this “Peruvian puzzle”, to elucidate the pelagic food-web structure and to better understand trophic interactions in the HCS, a combined stable isotope and fatty acid trophic biomarker approach was adopted for key zooplankton taxa and higher trophic positions with an extensive spatial coverage from 8.5 to 16°S and a vertical range down to 1,000 m depth. A pronounced regional shift by up to ∼5‰ in the δ15N baseline of the food web occurred from North to South. Besides regional shifts, δ15N ratios of particulate organic matter (POM) also tended to increase with depth, with differences of up to 3.8‰ between surface waters and the oxygen minimum zone. In consequence, suspension-feeding zooplankton permanently residing at depth had up to ∼6‰ higher δ15N signals than surface-living species or diel vertical migrants. The comprehensive data set covered over 20 zooplankton taxa and indicated that three crustacean species usually are key in the zooplankton community, i.e., the copepods Calanus chilensis at the surface and Eucalanus inermis in the pronounced OMZ and the krill Euphausia mucronata, resulting in an overall low number of major trophic pathways toward anchovies. In addition, the semi-pelagic squat lobster Pleuroncodes monodon appears to play a key role in the benthic-pelagic coupling, as indicated by highest δ13C’ ratios of −14.7‰. If feeding on benthic resources and by diel vertical migration, they provide a unique pathway for returning carbon and energy from the seafloor to the epipelagic layer, increasing the food supply for pelagic fish. Overall, these mechanisms result in a very efficient food chain, channeling energy toward higher trophic positions and partially explaining the “Peruvian puzzle” of enormous fish production in the HCS.

scholarly journals rescomp: An R package for defining, simulating and visualizing ODE models of consumer-resource interactions

2022 ◽  
Author(s):  
Andrew D Letten
Keyword(s):  
Resource Competition ◽  
R Package ◽  
Type I ◽  
Functional Responses ◽  
Ode Models ◽  
Wide Range ◽  
Resource Interactions ◽  
Barrier To Entry ◽  
Dependent Growth ◽  
Consumer Resource

Mechanistic models of resource competition underpin numerous foundational concepts and theories in ecology, and continue to be employed widely to address diverse research questions. Nevertheless, current software tools present a comparatively steep barrier to entry. I introduce the R package rescomp to support the specification, simulation and visualisaton of a broad spectrum of consumer-resource interactions. rescomp is compatible with diverse model specifications, including an unlimited number of consumers and resources, different consumer functional responses (type I, II and III), different resource types (essential or substitutable) and supply dynamics (chemostats, logistic and/or pulsed), delayed consumer introductions, time dependent growth and consumption parameters, and instantaneous changes to consumer and/or resource densities. Several examples on implementing rescomp are provided. In addition, a wide variety of additional examples can be found in the package vignettes, including using rescomp to reproduce the results of several well known studies from the literature. rescomp provides users with an accessible tool to reproduce classic models in ecology, to specify models resembling a wide range of experimental designs, and to explore diverse novel model formulations.

scholarly journals The pelagic microbial food web structure in Sanggou Bay, Yellow Sea: Spatial variation over four successive seasons

2016 ◽  
Author(s):  
Xue Chen ◽  
Wuchang Zhang ◽  
Michel Denis ◽  
Yuan Zhao ◽  
Lingfeng Huang ◽  
...  
Keyword(s):  
Food Web ◽  
Yellow Sea ◽  
Environmental Variables ◽  
Microbial Food Web ◽  
Similar Data ◽  
Food Web Structure ◽  
Data Set ◽  
Sanggou Bay ◽  
Web Structure ◽  
Metabolic Control Theory

Abstract. Sanggou Bay (Yellow Sea, China) is a small semi-closed bay in the eastern part of the Shandong Peninsula. In order to characterise the Sanggou Bay microbial food web (MFW) structure, we first documented, over four successive seasons, the distributions of environmental variables and abundances and biomasses of heterotrophic prokaryotes (HP), Synechococcus (SYN), picoeukaryrotes (PEUK), heterotrophic and pigmented nanoflagellates (HNF & PNF) and ciliates. The four season distributions in the Sanggou Bay of environmental variables and MFW components were submitted to cluster analysis, leading to distinguish Inner Bay and Outer Bay clusters at each season. In addition, Outer Bay MFW was found identical to the Inner Bay one but with a delay of one season, thus limiting to 4 the number of MFW characterising Sanggou Bay in that survey. We confirmed the existence of a strong relationship between HNF and HP, and extended this empirical relationship to the other MFW components: SYN, PEUK, PNF and ciliates. We also established upper and lower empirical linear boundaries for all the MFW component relationships with HP. The existence of these boundaries in the complex system made by the MFW stresses the need for systemic studies like the ones conducted for multi-enzyme systems and metabolic pathways that lead to the metabolic control theory. To better determine the MFW structure, we normalised for each sample, the biomass of the MFW components by that of HP. The normalised biomasses of SYN, PEUK, PNF and HNF had obvious seasonal variations with high values in summer or autumn, while ciliate normalised biomasses were low in summer and exhibited high values in winter. The main MFW-structure difference between Inner and Outer Bay clusters came from biomass differences for SYN, PEUK and PNF, whereas other component biomass-values were similar between Inner and Outer Bay clusters. Our study showed that the normalisation method could be used in other marine area to study the microbial food web structure. Indeed, the efficiency of this approach to determine MFW structure was demonstrated by successfully applying it to a similar data set from the literature and related to the Arabian Sea.

Head Position Identification

1967 ◽  
Vol 10 (3) ◽  
pp. 438-448
Author(s):  
H. N. Wright
Keyword(s):  
Roc Curve ◽  
Head Position ◽  
Hearing Impaired ◽  
Type Ii ◽  
Experimental Conditions ◽  
Partial Explanation ◽  
Complex Sounds ◽  
Binaural Cues ◽  
Criterion Behavior ◽  
Stimulus Degradation

A binaural recording of traffic sounds that reached an artificial head oriented in five different positions was presented to five subjects, each of whom responded under four different criteria. The results showed that it is possible to examine the ability of listeners to localize sound while listening through earphones and that the criterion adopted by an individual listener is independent of his performance. For the experimental conditions used, the Type II ROC curve generated by manipulating criterion behavior was linear and consistent with a guessing model. Further experiments involving different degrees of stimulus degradation suggested a partial explanation for this finding and illustrated the various types of monaural and binaural cues used by normal and hearing-impaired listeners to localize complex sounds.

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