Aggregation and removal of weak-links in food-web models: system stability and recovery from disturbance

Pinnegar, John K.; Blanchard, Julia L.; Mackinson, Steven; Scott, Richard; Duplisea, Daniel E.

doi:10.1016/j.ecolmodel.2004.09.003

Cited by 92 publications

(57 citation statements)

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“…These configurations primarily differed for the invertebrate functional groups. Pinnegar et al (2005) tested aggregation schemes emphasizing different parts of the food web (fish, marine mammals, and invertebrates) and reported greater variation for the same 2 indices compared to our results. Nevertheless, in a recent meta-analysis on 105 food-web models from different areas of the world, %A proved to be robust to the model construction in terms of the number of functional groups (Heymans et al 2014).…”

Section: Aggregating Trophic Groupscontrasting

confidence: 50%

“…The issue of the ecosystem indices' dependence upon the model structure has been largely discussed in the literature. Many studies have concluded that food-web properties are affected not only by the reduction in the number of compartments, but also and primarily by the way the functional groups are aggregated in such compartments (Christensen 1995, Abarca-Arenas & Ulanowicz 2002, Fulton et al 2003, Pinnegar et al 2005. Until further knowledge is obtained, models built in a standardized way, at least for similar ecosystems, could increase the reliability of model comparisons over time and/or space (Dame & Christian 2006, Fulton 2010.…”

Section: Aggregating Trophic Groupsmentioning

confidence: 99%

“…Species aggregation is thus necessary, but can strongly influence the model outputs. The over-aggregation of certain components of the food web, at either the upper or lower trophic levels, produces models with very different behaviours (Pinnegar et al 2005) and has sometimes led to dissimilar and conflicting recommendations for management action (Punt & Butterworth 1995, Yodzis 2001. In addition, Ecopath models require a large amount of input data, the quality of which can vary significantly.…”

Section: Introductionmentioning

confidence: 99%

“…The use of ecosystem models such as the EwE model is generally constrained by 2 major sources of uncertainty: (1) structural complexity (Abarca-Arenas & Ulanowicz 2002, Fulton et al 2003, Pinnegar et al 2005, Johnson et al 2009), and (2) the amount and quality of the input data (Essington 2007, Link 2010, Fulton 2010, Kearney et al 2013, Lassalle et al 2014. Structural complexity in Ecopath models is measured as the number of compartments in the model, the way species are aggregated in these compartments, and the inclusion of stanzas, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Balancing complexity and feasibility in Mediterranean coastal food-web models: uncertainty and constraints

Prato¹,

Gascuel²,

Valls³

et al. 2014

Mar. Ecol. Prog. Ser.

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Mass-balance trophic models (Ecopath and EcoTroph) are valuable tools that can be used to describe ecosystem structure and functioning, identify target species to be monitored, and allow comparisons of ecosystem states under different management options. Nevertheless, the Ecopath modelling approach is constrained by 2 major sources of uncertainty: model complexity and input data quality. We developed an approach for identifying the optimum model structure that considers trade-offs between feasibility, complexity, and uncertainty, using a Mediterranean coastal ecosystem as a case study. We began with an existing well-documented and good-quality food-web model comprising 41 functional groups at Port-Cros National Park, France. Based on this model, we assessed the effects of different aggregation choices, driven by a simplification of sampling effort, on the Ecopath and EcoTroph model outputs. We identified the functional groups in which imprecise biomass input significantly influenced the food-web model, and measured the relative effects on the ecosystem trophic structure and ecosystem maturity and complexity indices. A simplified model comprising 32 functional groups was identified as the best compromise between model complexity and reliability. High trophic level predators, abundant primary producers, and groups with a high biomass and/or diversified diet significantly influenced the model structure. We concluded that the collection of local and accurate biomass data, especially for the most influential functional groups we identified, should be a priority when developing food-web models for similar ecosystems. Our method enables simplified and standardized models, while considering both the feasibility and reliability of the Ecopath and EcoTroph applications for Mediterranean coastal ecosystems.

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Section: Aggregating Trophic Groupscontrasting

confidence: 50%

Section: Aggregating Trophic Groupsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Balancing complexity and feasibility in Mediterranean coastal food-web models: uncertainty and constraints

Prato¹,

Gascuel²,

Valls³

et al. 2014

Mar. Ecol. Prog. Ser.

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“…Smith et al (2011) suggested their reference point based on the proportion of trophic groups that were depleted by > 40%. The aggregation of organisms into trophic groups is one of the key issues in ecosystem models (Pinnegar et al 2005). It would be useful to assess the sensitivity of derived reference points to aggregation assumptions.…”

Section: Figurementioning

confidence: 99%

From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

Hill

2013

Envir. Conserv.

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SUMMARYThe goals of ecosystem based management (EBM) are strategically ambiguous, meaning that they require interpretation to identify objectives for ecosystem state. Ecosystem states that are useful for achieving such objectives are known as reference points. Soft reference points specify both a state and a probability of the ecosystem being in that state. They are used with simulation models to identify management measures for which the risk of the ecosystem entering an undesirable state is below a specified level. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for the EBM of Antarctic krill fisheries. CCAMLR used soft reference points for the krill stock in the Scotia Sea and southern Drake Passage to set a regional catch limit. However, this catch limit needs spatial subdivision to protect predators from localized depletion. Modelbased evaluations of different options for subdividing the catch limit used illustrative reference points to assess the depletion risk to multiple predators. This study demonstrates that the apparent risk is sensitive to the choice of reference point and method for aggregating modelled predators. EBM practitioners and stakeholders need to be aware that these factors could therefore bias comparisons of management measures. Nonetheless, qualitative distinctions between different spatial subdivision options are relatively consistent except at high levels of aggregation and extreme reference points. This study also demonstrates a lack of generality in the relationship between current and future ecosystem state. Thus, the EBM goal of maintaining ecosystem resilience implies different reference points for the current state of different ecosystem components. Despite early progress in defining soft reference points for the krill stock, CCAMLR has not yet defined reference points for krill predators. Structured dialogue aimed at identifying collective objectives * Correspondence: Dr Simeon Hill e-mail: sih@bas.ac.uk The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence . The written permission of Cambridge University Press must be obtained for commercial re-use. might be necessary to achieve further progress in CCAMLR and other EBM organizations.

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For flux's sake: General considerations for energy‐flux calculations in ecological communities

Eisenhauer

Barnes

Brose

et al. 2021

Ecology and Evolution

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Aggregation and removal of weak-links in food-web models: system stability and recovery from disturbance

Cited by 92 publications

References 50 publications

Balancing complexity and feasibility in Mediterranean coastal food-web models: uncertainty and constraints

Balancing complexity and feasibility in Mediterranean coastal food-web models: uncertainty and constraints

From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

For flux's sake: General considerations for energy‐flux calculations in ecological communities

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