MEPS 512:71-88 (2014)  -  DOI:

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

Giulia Prato1,*, Didier Gascuel2, Audrey Valls3, Patrice Francour1

1Université de Nice Sophia Antipolis, Faculté de Sciences, EA 4228 ECOMERS, 06108 Nice cedex 2, France
2Université Européenne de Bretagne, UMR Agrocampus ouest/INRA Ecologie et Santé des Ecosystèmes,
65 rue de Saint Brieuc, CS 84215, 35042 Rennes cedex, France
3University of British Columbia, Fisheries Centre, Vancouver, British Columbia V6T1Z4, Canada
*Corresponding author:

ABSTRACT: 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.

KEY WORDS: Aggregation · Uncertainty · Complexity · Trophic spectrum · Ecosystem indices · Biomass · Ecopath · EcoTroph · Mediterranean Sea

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Cite this article as: Prato G, Gascuel D, Valls A, Francour P (2014) Balancing complexity and feasibility in Mediterranean coastal food-web models: uncertainty and constraints. Mar Ecol Prog Ser 512:71-88.

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