ABSTRACT
Feeding Biology and Ecology Susana Garrido1,* and Carl David van der Lingen2
Small pelagic fi sh such as sardines and anchovies are generally the most abundant species in the most productive regions of the world’s oceans (Checkley et al. 2009), particularly in upwelling regions where they occupy a fundamental intermediate trophic level (Bakun 2006). Small pelagic fi sh were previously thought to largely control the variability of these upwelling ecosystems by exerting top-down control on plankton and bottom-up control on top predators, and because typically only a few species occupy this critical trophic level (in contrast to a high species diversity at lower and upper trophic levels) such ecosystems were described as showing a “wasp-waist” confi guration (Rice 1995, Bakun 1996). More recently, however, a comparison of the species composition, dominant species richness and species evenness within functional groups in the four major Eastern Boundary Current Upwelling Systems (EBUS), and quantifi cation of trophic fl ows within these systems, did not support the wasp-waist hypothesis (Fréon et al. 2009) except possibly for the Benguela Current system (Cury et al. 2000). Similarly, recent work using stable isotopes to assess the foodweb structure in the California Current system has also challenged the assumption of wasp-waist architecture (Madigan et al. 2012),
1Centro de Oceanografi a, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Avenida Nossa Senhora do Cabo, nº939, 2750-374 Cascais-Portugal. 2Branch: Fisheries Management, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, South Africa; and Marine Research Institute, University of Cape Town, Private Bag X3, Rondebosch 7700, South Africa. Email: Carl.vanderlingen@gmail.com *Corresponding author: garridosus@gmail.com
with the pelagic food web in the California Current being more stable and diverse due to the omnivory and diversity of foraging strategies exhibited by predators there. Despite these studies, the importance of small pelagic fi sh in upwelling and other ecosystems is indisputable because of the high biomass that their populations can attain and the important role these species play in energy transfer from plankton to higher trophic levels.
