Journal Article

Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models

Coleen L. Moloney, Astrid Jarre, Hugo Arancibia, Yves-Marie Bozec, Sergio Neira, Jean-Paul Roux and Lynne J. Shannon

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 62, issue 3, pages 493-502
Published in print January 2005 | ISSN: 1054-3139
Published online January 2005 | e-ISSN: 1095-9289 | DOI: https://dx.doi.org/10.1016/j.icesjms.2004.11.009
Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models

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Large-scale, mass-balance trophic models have been developed for northern and southern regions of both the Benguela and Humboldt upwelling ecosystems. Four of these Ecopath models were compared and calibrated against one another. A common model structure was established, and a common basis was used to derive poorly known parameter values. The four resulting models represent ecosystems in which the main commercial fish species have been moderately to heavily fished: central-southern Chile (1992), northern-central Peru (1973–1981), South Africa (1980–1989), and Namibia (1995–2000). Quantitative ecosystem indicators derived from these models were compared. Indicators based on large flows (involving low trophic levels) or top predators were not well estimated, because of aggregation problems. Many of the indicators could be contrasted on the basis of differences between the Benguela and Humboldt systems, rather than on the basis of fishing impact. These include integrated values relating to total catches, and trophic levels of key species groups. Indicators based on integrated biomass, total production, and total consumption tended to capture differences between the model for Namibia (where fish populations were severely reduced) and the other models. We conclude that a suite of indicators is required to represent ecosystem state, and that interpretation requires relatively detailed understanding of the different ecosystems.

Keywords: eastern boundary currents; ecosystem approach; ecosystem indicators; fishing impact; large coastal upwelling ecosystems; trophic flow network analysis

Journal Article.  4793 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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