Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS
algae system (Sala & Zabala, 1996). In this light, considering the potential role of
predation on P. lividus recruits in regulating their abundance, this study planned: (1) to
individuate the predators of P. lividus recruits and evaluate their predation rates, (2) to
compare the abundance of predators of early settled P. lividus in barren and erect
macroalgae systems.
Materials and methods – The study area included the Medes Island Marine Reserve
and the nearby Montgri unprotected area (NW Mediterranean Sea) in summer 2009.
The study was carried out on rocky bottoms at 5-8 m depth, characterized by two
distinct types of algal assemblage state including: (1) Barren State (BS), dominated by
encrusting corallines (Lithophyllum incrustans, Mesophyllum alternans, Spongites
notarisii) and (2) Erect macroalgae state (EAS) dominated by a canopy of perennial
(e.g. Cystoseira compressa, Codium vermillara) and seasonal (e.g.: Dictyota
dichotoma, Asparagopsis armata) macroalgae and understorey species (e.g.: Corallina
elongata, Rhodymenia ardissonei, Halopteris filicina).
In order to individuate the potential predators of P. lividus juveniles and their predation
rates, we exposed young sea urchin settlers to a variety of decapod crustaceans in the
laboratory, based on our previous experiments and on the literature (Scheibling &
Robinson, 2008). Decapods and sea urchin juveniles were collected by scraping off
rocky substrates. In the laboratory, small decapods (