Trophic Structure and Community Stability in an Overfished Ecosystem

Abstract

Gobbled by Gobies A common feature of overfished marine ecosystems is a tendency for biomass to become dominated by jellyfish and microbes, and for the habitat to become anoxic or hypoxic as large fish species are removed. The Benguela ecosystem off the coast of Namibia is a case in point. Utne-Palm et al. (p. 333 ) describe how the loss of overfished sardines from the Benguela fishery has provided an opportunity for an endemic fish species, the bearded goby, to exploit jellyfish and microbial biomass and to increase in number. These small fish have in turn become the predominant prey species for the larger fish, birds, and mammals in the region. The significance of the goby lies in its ability to forage on resources traditionally regarded as “dead-ends.” The bearded goby has thus become a key stabilizing component to the turnover of energy in the Benguela ecosystem.