Risk allocation hypotheses and trophic cascades: the effect of variable risk predation environments on the feeding behavior of the herbivorous Littorina obtusata and the induced defenses of the macroalgae Ascophyllum nodosum

• Grant number: 12/03650-3
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: July 25, 2012
• End date: July 24, 2013
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Augusto Alberto Valero Flores
• Grantee: María Soledad López
• Supervisor: Stuart Rees Jenkins
• Host Institution: Centro de Biologia Marinha (CEBIMAR). Universidade de São Paulo (USP). São Sebastião , SP, Brazil
• Institution abroad: Bangor University, Wales
• Associated to the scholarship: 09/07678-7 - Experimental assessment of the lethal and non-lethal effects of benthic predators with different feeding strategies, Eriphia gonagra e Thais haemastoma, on the bivalve Perna perna, BP.PD

Abstract

The anti-predator behavior can diminish prey vulnerability and predation intensity (non-lethal effects). Non-lethal effects could be propagated to other trophic levels in trophic cascades. To test those effects, prey are often continuously exposed to predator cues that are compared with no exposition treatments. More than continuous, the risk of predation is highly variable in space and time, so the non-lethal effects can be less strong that it has been estimated by continuous risk exposition experiments. The Risk Allocation Hypotheses included temporal variability of predation risk and could be a more realistic form to understand the non-lethal effects, but it has been little tested using marine organisms. In my post-doctoral work in Brazil, I used a continuous risk approach to test non-lethal effects and trophic cascades. During my time in Wales I plan to test the Risk Allocation Hypotheses, using the crab Carcinus maenas to create variable risk scenarios, its effects on feeding behavior of the herbivorous Littorina obtusata and the cascade effects on the brown macroalgae Ascophyllum nodosum phenotype. In lab experiments, risk variability will be simulated by treatments with different crab abundances and proportion of time that gastropods spend in risk environments. Number and localization of herbivorous injuries, growth, C:N ratio and phlorotanins (inducible chemical defense) will be quantified in macroalgae tissues. Also, it will be assessed the resistance to further herbivorous attacks of the macroalgaes with previous herbivorous contact. With this project we will assess relevant and under current debate questions on ecology which are still little tested. (AU)