Associação de anfípodes com algas: efeitos da identidade da alga hospedeira, predação e comportamento alimentar de anfípodes

Author(s)

Glauco Barreto de Oliveira Machado

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2018-05-14

Examining board members

Fosca Pedini Pereira Leite; Antonia Cecília Zacagnini Amaral; Tânia Marcia Costa; Marcel Okamoto Tanaka; Gustavo Muniz Dias

• Advisor: Fosca Pedini Pereira Leite

Abstract

Seaweeds play a key role on rocky shores by providing shelter and food for several species. The traits of such biological substrates, as well as the predation pressure, influence the abundance and diversity of the associated fauna, especially amphipods. Also, the feeding behavior of herbivorous amphipods can affect the association of such consumers with their algal hosts. Herein, we investigated the role of algal host identity, predation pressure and amphipods¿ feeding behavior on the association of amphipods with seaweeds. Specifically, we investigated (1) the effect of algal host identity on the density and composition of amphipods and on the vulnerability of these animals to predation, (2) the effect of algal host identity on the distribution, feeding behavior and vulnerability to predation of the herbivorous amphipod Cymadusa filosa and (3) how the nutritional variation among different algae influences the feeding behavior of the generalist herbivorous amphipod Ampithoe valida. The association of amphipods with three algal hosts was evaluated seasonally over one year. The composition of the amphipod assemblage was sensitive to the algal host identity and varied temporarily. From a field experiment, no clear effect of predation on amphipod¿s assemblage was found. Also, predation did not explain the spatial (i.e. among algal hosts) and temporal variation of amphipod¿s assemblage. The density of C. filosa differed between species of algal hosts. From feeding and performance experiments with C. filosa at laboratory, it was observed that the distribution of this herbivore was only partially explained by the food value of algal hosts. In this case, from a field experiment, it was observed that predation is a limiting factor for the occurrence of C. filosa on high-quality food hosts. From feeding experiments, it was estimated the intake of nutrients (i.e., carbon, nitrogen, protein and non-protein compounds) by A. valida. Such amphipod was able to regulate the intake of nutrients, mainly protein, alleviating the problem of nutritional variation among different algae. Our results emphasize the importance of algal host identity for the association of amphipods with seaweeds. Also, the value of algae as a refuge against predation is an important limiting factor for generalist herbivores, since their requirement for a suitable shelter seems to be more important than the food value of algal hosts. In such case, those herbivores may employ behavioral strategies to overcome the low nutritional quality of algal foods that offer suitable shelter against predators. Therefore, considering the role of algal host identity on the composition of associated fauna, the loss of such habitat-forming organisms is expected to have drastic consequences on the diversity of associated fauna and, consequently, on the flow of matter and energy in coastal ecosystems (AU)

• FAPESP's process: 13/17629-9 - Predation on herbivorous amphipods associated to macroalgae: role of the host and the characteristics of herbivore
• Grantee: Glauco Barreto de Oliveira Machado
• Support Opportunities: Scholarships in Brazil - Doctorate