Predation and interaction strength of octopuses and sea stars on different functional groups of the rocky intertidal shores of the Patagonian coast

  • Lorena P. StoreroEmail author
  • Matías Ocampo Reinaldo
  • Maite A. Narvarte
  • Oscar O. Iribarne


Predation is one of the main structuring forces in rocky intertidal communities, though with an effect depending on the environmental context and conditions. On the stressful Patagonia shores of Argentina, experimental studies concluded that predation does not play a significant ecological role. In the biogeographic transition zone of northern Patagonia, where medium-sized predators (like octopuses and sea stars) coexist and are relatively abundant, the effect of predators in the rocky intertidal zone was never tested. The present study evaluated the effect of two intertidal predators, the small octopus Octopus tehuelchus (d’Orbigny, 1834) and the sea star Anasterias antarctica (Lütken, 1857), on the abundance of prey and the interaction strength of these predators on different functional groups in a mid-intertidal rocky community of northern Patagonia. To do so, we conducted a short-term-exclusion experiment in the mid-intertidal area and estimated the interaction strength through dynamic indices. Our experimental exclusion of octopuses and sea stars had no positive effect on the abundance of prey in a short-term period, adding evidence that predation remains weak even in north Patagonia (i.e., under ameliorated physical stress), even with a relatively high abundance of predators. The combined interaction strength of those consumers on prey in the different functional groups was weak, with the dynamic indices being positive for mobile grazers and scavengers and negative for sessile filter feeders. These results emphasize the significance and deepen the understanding of the role of consumers, food web linkages, and community function in the biogeographic transition zone of north Patagonia.


Predation Interaction strength Octopus Sea star Rocky shores North Patagonia 



LPS thanks Dr. Raúl González, Dr. Andrea Roche, Agustín Bianchini, and Nicolás Cetra for their assistance during the field experiments. This work was funded by Agencia Nacional de Promoción Científica y Tecnológica (PICT 2013 No. 1926 and PICT 2017 No. 2383 to LPS).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Human and animal rights

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Dr. Donald F. Haggerty, a retired academic career investigator, and native English speaker edited the final version of the manuscript.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos Almirante Storni (CIMAS) – CONICET/UNCo/Río NegroSan Antonio OesteArgentina
  2. 2.Escuela Superior de Ciencias MarinasUniversidad Nacional del ComahueSan Antonio OesteArgentina
  3. 3.Instituto de Investigaciones Marinas y Costeras (IIMyC) - CONICET-UNMDPMar del PlataArgentina

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