Feeding behavior of Pachygrapsus transversus: influence of prey size and impact of waves

• Grant number: 10/08461-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2010
• End date: March 31, 2011
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Ronaldo Adriano Christofoletti
• Grantee: Carolina Toledo Andreu
• Host Institution: Centro de Biologia Marinha (CEBIMAR). Universidade de São Paulo (USP). São Sebastião , SP, Brazil

Abstract

Rocky shore environments have high biological interactions and are of great importance for several species of fauna and flora associated. Among these interactions, predation is important because it can control the structure of communities. In our Brazilian coast, recent studies show Pachygrapsus transversus crab as a main consumer in the rocky intertidal, which, despite being considered an omnivorous animal, it has a preference for animal groups. Thisstudy aims to evaluate the theory of optimal foraging by the test screening prey size by crabs at different stages of their ontogeny, andobserve the influence of ripple in the foraging behavior of the predator. Moreover, it will be considered as an important factor bioinvasion analysis, through the use of native and exotic prey.Aquariums of 20x20x30 cm with an adult or juvenile crab per tank will be used. Mussel species Brachidontes spp. and Isognomon bicolor will serve as potential prey, which will be divided into three size classes: recruits, juveniles and adults, and will be offered to the predator for a period of 48 hours in mono and polyculture. For the experiment of the effect of the waves, the animals will be arranged in two types of systems, one with ripple and one without it, thus representing sheltered and exposed beaches. The experiment will be conducted in the laboratory and waving will be generated through a lever mechanism, and then, it will be offered a plate of mussels, the foraging time and displacement of crab on each system will be observed.