Beyond the defaults: functional response parameter space and ecosystem-level fishing thresholds in dynamic food web model simulations

2012 ◽  
Vol 69 (12) ◽  
pp. 2077-2094 ◽  
Author(s):  
Sarah K. Gaichas ◽  
Garrett Odell ◽  
Kerim Y. Aydin ◽  
Robert C. Francis
Keyword(s):  
Food Web ◽  
Functional Response ◽  
Fishery Management ◽  
Gulf Of Alaska ◽  
Threshold Effect ◽  
Model Simulations ◽  
Response Parameter ◽  
Model Ecosystems ◽  
Wide Range ◽  
Food Web Model

Dynamic food web models are increasingly used to investigate the ecosystem effects of fishing; however, key unknown functional response parameters describing predator-prey interactions strongly influence model behavior. We explored functional response parameter uncertainty and its effect on fishing simulation results using a dynamic food web model of the Gulf of Alaska (GOA) with14 fishing fleets, 104 consumer groups, four primary producer groups, and five detritus pools. After generating millions of potential ecosystems with randomly selected functional response parameters, we assigned groups of these randomly parameterized systems to one of five increasingly intense ecosystem-wide fishing treatments. For each fishing treatment, we counted and compared resulting ecosystems with no extinctions. Surprisingly, the model GOA ecosystems were robust to a wide range of functional response parameters. However, we found an abrupt threshold effect between moderate and heavy exploitation rates, beyond which a much lower proportion of model ecosystems persisted. Beyond this fishing threshold, extinction was more likely, and system attributes differed greatly from moderately fished model ecosystems. Fishing thresholds were not found with default functional response parameters, implying that model simulations should include a wide range of parameterizations to reflect ecological uncertainty and to support sustainable ecosystem-based fishery management.

Impact of fear on delayed three species food-web model with Holling type-II functional response

2021 ◽  
Author(s):  
S. Magudeeswaran ◽  
S. Vinoth ◽  
K. Sathiyanathan ◽  
M. Sivabalan
Keyword(s):  
Hopf Bifurcation ◽  
Food Web ◽  
Functional Response ◽  
Local Stability ◽  
Type Ii ◽  
Normal Form Theory ◽  
The Third ◽  
Delayed System ◽  
Food Web Model ◽  
Type Ii Functional Response

This paper deals with the investigation of the three species food-web model. This model includes two logistically growing interaction species, namely [Formula: see text] and [Formula: see text], and the third species [Formula: see text] behaves as the predator and also host for [Formula: see text]. The species [Formula: see text] predating on the species [Formula: see text] with the Holling type-II functional response, while the first species [Formula: see text] is benefited from the third species [Formula: see text]. Further, the effect of fear is incorporated in the growth rate of species [Formula: see text] due to the predator [Formula: see text] and time lag in [Formula: see text] due to the gestation process. We explore all the biologically possible equilibrium points, and their local stability is analyzed based on the sample parameters. Next, we investigate the occurrence of Hopf-bifurcation around the interior equilibrium point by taking the value of the fear parameter as a bifurcation parameter for the non-delayed system. Moreover, we verify the local stability and existence of Hopf-bifurcation for the corresponding delayed system. Also, the direction and stability of the bifurcating periodic solutions are determined using the normal form theory and the center manifold theorem. Finally, we perform extensive numerical simulations to support the evidence of our analytical findings.

Network models for ecosystem-based fishery analysis: a review of concepts and application to the Gulf of Alaska marine food web

2008 ◽  
Vol 65 (9) ◽  
pp. 1965-1982 ◽  
Author(s):  
Sarah K. Gaichas ◽  
Robert C. Francis
Keyword(s):  
Food Web ◽  
Fishery Management ◽  
Marine Ecosystem ◽  
Stomach Contents ◽  
Network Models ◽  
Small World ◽  
Gulf Of Alaska ◽  
Quantitative Information ◽  
Scale Free ◽  
Structural Impacts

We apply graph theory and network analysis to the food web of the Gulf of Alaska marine ecosystem to classify its structural properties, which suggest how the ecosystem as a whole may respond to heavy fishing pressure on its components. Three conceptual models of network structure, random, small-world, and scale-free, each have different implications for system behavior and tolerance to perturbations. We constructed two food web network models using detailed quantitative information on the stomach contents of 57 predator (fish) species collected during trawl surveys of the Gulf of Alaska between 1981 and 2002. The resulting food webs displayed both small-world and scale-free network properties, suggesting that impacts on one species might spread to many through short interaction chains and that while most food web connections are not critical, a small set of fished species support critical structural connections. Ecosystem-based fishery management should therefore first focus on protecting the highly connected species in the network to avoid structural impacts of fishing on the food web.

scholarly journals Experimental duration and predator satiation levels systematically affect functional response parameters

2017 ◽  
Author(s):  
Yuanheng Li ◽  
Björn C. Rall ◽  
Gregor Kalinkat
Keyword(s):  
Food Web ◽  
Functional Response ◽  
Large Data ◽  
Handling Time ◽  
Set Covering ◽  
Parameter Estimates ◽  
Functional Responses ◽  
Predator Satiation ◽  
Data Set ◽  
Wide Range

AbstractEmpirical feeding studies where density-dependent consumption rates are fitted to functional response models are often used to parametrize the interaction strengths in models of population or food-web dynamics. However, the relationship between functional response parameter estimates from short-term feeding studies and real-world, long-term, trophic interaction strengths remains largely untested. In a critical first step to address this void, we tested for systematic effects of experimental duration and predator satiation on the estimation of functional response parameters, namely attack rate and handling time. Analyzing a large data set covering a wide range of predator taxonomies and body sizes we show that attack rates decrease with increasing experimental duration, and that handling times of starved predators are consistently shorter than those of satiated predators. Therefore, both the experimental duration and the predator satiation level have a strong and systematic impact on the predictions of population dynamics and food-web stability. Our study highlights potential pitfalls at the intersection of empirical and theoretical applications of functional responses. We conclude our study with some practical suggestions how these implications should be addressed in the future to improve predictive abilities and realism in models of predator-prey interactions.

scholarly journals Pattern formation in three species food web model in spatiotemporal domain with Beddington–DeAngelis functional response

2014 ◽  
Vol 19 (2) ◽  
pp. 155-171 ◽  
Author(s):  
Randhir Singh Baghel ◽  
Joydip Dhar
Keyword(s):  
Food Web ◽  
Functional Response ◽  
State Variables ◽  
Instability Condition ◽  
First Order ◽  
Interior Equilibrium ◽  
Temporal System ◽  
Different Types ◽  
And Diffusion ◽  
Food Web Model

A mathematical model is proposed to study a three species food web model of preypredator system in spatiotemporal domain. In this model, we have included three state variables, namely, one prey and two first order predators population with Beddington-DeAngelis predation functional response. We have obtained the local stability conditions for interior equilibrium and the existence of Hopf-bifurcation with respect to the mutual interference of predator as bifurcation parameter for the temporal system. We mainly focus on spatiotemporal system and provided an analytical and numerical explanation for understanding the diffusion driven instability condition. The different types of spatial patterns with respect to different time steps and diffusion coefficients are obtained. Furthermore, the higher-order stability analysis of the spatiotemporal domain is explored.

scholarly journals Effects of sample gear on estuarine nekton assemblage assessments and food web model simulations

2021 ◽  
Vol 133 ◽  
pp. 108404
Author(s):  
Megan K. La Peyre ◽  
Shaye Sable ◽  
Caleb Taylor ◽  
Katherine S. Watkins ◽  
Erin Kiskaddon ◽  
...  
Keyword(s):  
Food Web ◽  
Model Simulations ◽  
Food Web Model

scholarly journals Prey body mass and richness underlie the persistence of a top predator

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190622 ◽  
Author(s):  
Laura Melissa Guzman ◽  
Diane S. Srivastava
Keyword(s):  
Food Web ◽  
Functional Response ◽  
Body Mass ◽  
Prey Species ◽  
Handling Time ◽  
Predator Prey ◽  
Prey Diversity ◽  
Prey Interaction ◽  
Range Of Values ◽  
Food Web Model

Predators and prey often differ in body mass. The ratio of predator to prey body mass influences the predator's functional response (how consumption varies with prey density), and therefore, the strength and stability of the predator–prey interaction. The persistence of food chains is maximized when prey species are neither too big nor too small relative to their predator. Nonetheless, we do not know if (i) food web persistence requires that all predator–prey body mass ratios are intermediate, nor (ii) if this constraint depends on prey diversity. We experimentally quantified the functional response for a single predator consuming prey species of different body masses. We used the resultant allometric functional response to parametrize a food web model. We found that predator persistence was maximized when the minimum prey size in the community was intermediate, but as prey diversity increased, the minimum body size could take a broader range of values. This last result occurs because of Jensen's inequality: the average handling time for multiple prey of different sizes is higher than the handling time of the average sized prey. Our results demonstrate that prey diversity mediates how differences between predators and prey in body mass determine food web stability.

Use of Functional Response Modeling to Evaluate the Effect of Temperature on Predation of Amblyseius swirskii (Acari: Phytoseiidae) Adults Preying on Tetranychus urticae (Acari: Tetranychidae) Nymphs

2021 ◽  
Author(s):  
Azadeh Farazmand ◽  
Masood Amir-Maafi
Keyword(s):  
Functional Response ◽  
Tetranychus Urticae ◽  
Attack Rate ◽  
Handling Time ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
Temperature Threshold ◽  
Amblyseius Swirskii ◽  
Functional Responses ◽  
Wide Range

Abstract In this research, functional responses of Amblyseius swirskii Athias-Henriot preying on different Tetranychus urticae Koch nymphal densities (2, 4, 8, 16, 32, 64, and 128) were studied at eight constant temperatures (15, 20, 25, 27.5, 30, 32.5, 35 and 37.5°C) in a circular Petri dish (3-cm diameter × 1-cm height) under lab conditions. At all temperatures, the logistic regression showed a type II functional response. A nonlinear relationship was found between temperature and attack rate and the reciprocal of handling time. The reciprocal of handling time decreased exponentially with increasing temperature. In contrast, the attack rate grew rapidly with increasing temperatures up to an optimum, showing a decreasing trend at higher temperatures. In order to quantify the functional response of A. swirskii over a broad range of temperatures and to gain a better estimation of attack rate and handling time, a temperature-settled functional response equation was suited to our data. Our model showed that the number of prey consumed increased with rising prey density. Also, the predation rates increased with increasing temperatures but decreased at extremely high temperatures. Based on our model, the predation rate begins at the lower temperature threshold (11.73°C) and reaches its peak at upper temperature threshold (29.43°C). The coefficient of determination (R2) of the random predator model was 0.99 for all temperatures. The capability of A. swirskii to search and consume T. urticae over a wide range of temperatures makes it a good agent for natural control of T. urticae in greenhouses.

BIFURCATION AND CHAOS IN A DISCRETE PREDATOR–PREY MODEL WITH HOLLING TYPE-III FUNCTIONAL RESPONSE AND HARVESTING EFFECT

2021 ◽  
pp. 1-28
Author(s):  
ANURAJ SINGH ◽  
PREETI DEOLIA
Keyword(s):  
Functional Response ◽  
Sufficient Conditions ◽  
Flip Bifurcation ◽  
Bifurcation Structure ◽  
Bifurcation And Chaos ◽  
Predator Prey ◽  
Type Iii ◽  
Predator Prey Model ◽  
Prey Model ◽  
Wide Range

In this paper, we study a discrete-time predator–prey model with Holling type-III functional response and harvesting in both species. A detailed bifurcation analysis, depending on some parameter, reveals a rich bifurcation structure, including transcritical bifurcation, flip bifurcation and Neimark–Sacker bifurcation. However, some sufficient conditions to guarantee the global asymptotic stability of the trivial fixed point and unique positive fixed points are also given. The existence of chaos in the sense of Li–Yorke has been established for the discrete system. The extensive numerical simulations are given to support the analytical findings. The system exhibits flip bifurcation and Neimark–Sacker bifurcation followed by wide range of dense chaos. Further, the chaos occurred in the system can be controlled by choosing suitable value of prey harvesting.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

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