Teresa Cruz1, David Mateus1, Gonzalo Macho2,3, Katja J. Geiger4, Eric Thiébaut5, Joana N. Fernandes1, Alba Aguión3, Julio Arrontes4, Caroline Broudin5, David Jacinto1, Salvador Román3, Jorge Sostres4, Lucille Perrier5, Teresa Silva1, Elsa Vásquez3, José Manuel Rico4, Dominique Davoult5, João J. Castro1, Consolación Fernández4, Alina Sousa1, José Luis Acuña4
1University of Évora, Portugal - 2Fisherman’s Cove, Mahé, Seychelles - 3Universidade de Vigo, Spain - 4Universidad de Oviedo, Spain - 5Sorbonne Université, CNRS, Station Biologique de Roscoff, France
Predation is a fundamental structuring process on intertidal temperate reefs. Among the predators acting in these environments, humans can play a crucial role, particularly in exploited resources. Most research on the relative role played by predators in structuring intertidal communities has not taken place on very wave-exposed shores. Stalked barnacles of the species Pollicipes pollicipes are exploited throughout their geographic range (SW England to Senegal), namely in France, Spain and Portugal. This species lives in highly wave-exposed rocky shores, and its exploitation is considered a high-risk activity. With the overall aim of studying the effect of human predation and other macropredators on the density, biomass and size-structure of P. pollicipes in Europe, a manipulative experiment was carried out in various sites in Brittany (France), Asturias and Galicia (Spain), and SW Portugal. At each site, 35 x 35 cm metal cages with a wide mesh size (5 cm) were installed to deter human predation and reduce macro-predation by other organisms. Control plots were also considered. At the start of the experiment, at each site, the cover of P. pollicipes did not differ between the two treatments (cage and control). With the additional objective of evaluating the effect of protection time from macropredators, the total density, total biomass and size-structure of the barnacles were independently measured two years (2017-2019) and one year (2018-2019) after the set up. At the end of the experiment, in each plot, we measured the percentage cover of P. pollicipes by image analysis (QGIS software); and we placed a 15 x 15 cm area over a group of P. pollicipes, photographed and scraped the area to count, measure and weight the barnacles. Data are being analysed in a univariate (total density and biomass) and multivariate way (size-structure of density and biomass) in relation to the factors site, region, predation and protection time, as well as using a meta-analytical approach.
Biography
Teresa Cruz is an associate professor at the University of Évora, Portugal, and a researcher at MARE-Marine and Environmental Sciences Centre. Her main scientific area is the ecology of temperate reefs, with particular emphasis on research on the ecology, fishery and management of stalked barnacles. Her main “home” for fieldwork is the SW coast of Portugal.