ICES Journal of Marine Science: Journal du Conseil Advance Access originally published online on November 9, 2008
ICES Journal of Marine Science: Journal du Conseil 2009 66(1):64-71; doi:10.1093/icesjms/fsn176
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This article appears in the following ICES Journal of Marine Science issue: European Symposium on Marine Protected Areas as a Tool for Fisheries Management and Ecosystem Conservation [View the issue table of contents]
Evidence of the top–down role of predators in structuring sublittoral rocky-reef communities in a Marine Protected Area and nearby areas of the Canary Islands
1 Departamento de Biología Animal (Ciencias Marinas), Universidad de La Laguna, Avenida Francisco Sánchez s/n 38206, La Laguna, Islas Canarias
2 Biology Department, Villanova University, Villanova, PA, USA
Correspondence to S. Clemente: tel: +34 922 318387; fax: +34 922 318311; e-mail: msclemen{at}ull.es.
Clemente, S., Hernández, J. C., and Brito, A. 2009. Evidence of the top–down role of predators in structuring sublittoral rocky-reef communities in a Marine Protected Area and nearby areas of the Canary Islands. – ICES Journal of Marine Science, 66: 64–71.Differences in the sea urchin Diadema aff. antillarum population structure, which have been attributed to removal of predatory fish through overfishing, are observed throughout the Canary Islands. Low urchin abundances and a "desired conservation state" are currently found in Mar de Las Calmas Marine Protected Area and nearby fished areas (FAs) in El Hierro Island, in contrast to the occurrence of high urchin densities and the "undesired conservation state" in the highly FAs (HFAs) of Tenerife Island. Under these different levels of fishing pressure, we consider a set of ecological variables potentially affecting urchin populations (settlement, recruitment, adult urchin densities, predation rates, and abundance of urchin fish predators) to infer their magnitude and relative importance in addressing community-wide changes. No differences in settlement and recruitment rates were found, but predation pressure was higher in El Hierro, where adult density was low and predation rates were high. The combination of these factors provides evidence of a top–down control of sublittoral reef communities. Although the effect of protection was less clear, we demonstrate the positive effects of reduced fishing effort in enhancing trophic cascade processes and reducing the establishment of barren grounds.
Keywords: fish abundance, fishery restrictions, predation index, sea urchin abundance, sea urchin recruitment, sea urchin settlement
Received 26 October 2007; accepted 2 June 2008; advance access publication 9 November 2008.