© 2004 International Council for the Exploration of the Sea
Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models
a Marine Biology Research Institute, Zoology Department, University of Cape Town Rondebosch 7701, South Africa
b Danish Institute for Fisheries Research, Sea Fisheries Institute North Sea Centre, PO Box 101, DK-9850 Hirtshals, Denmark
c Sección Pesquerías, Departamento de Oceanografía, Universidad de Concepción PO Box 160-C, Concepción, Chile
d UR-CoRéUS/IRD, Département Halieutique ENSAR 65 rue de St-Brieuc, CS 84215, 35042 Rennes Cedex, France
e Programa de Magister en Ciencias Mención Pesquerías, Universidad de Concepción PO Box 160-C, Concepción, Chile
f Ministry of Fisheries and Marine Resources, Lüderitz Marine Research PO Box 394, Lüderitz, Namibia
g Marine and Coastal Management Private Bag X2, Rogge Bay 8012, South Africa
*Correspondence to C. L. Moloney: tel: +27 21 6502681; fax: +27 21 6503301. e-mail: cmoloney{at}botzoo.uct.ac.za.
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
Received 1 April 2004; accepted 15 October 2004.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. Libralato and C. Solidoro Comparing methods for building trophic spectra of ecological data ICES J. Mar. Sci., November 5, 2009; (2009) fsp249v1. [Abstract] [Full Text] [PDF]
|
|