How microspatial diferences of abiotic conditions affect the recruitment and predation on the encrusting community and the fitness of the bryozoan Schyzoporella errata?

Abstract

The spatial heterogeneity of environmental conditions and the genetic variability interact to determine the polymorphism of populations. While the factors that create the differences in phenotypes among different populations are well known, a few empiric studies have addressed how the heterogeneity of the environment in small scale contributes to create and maintain the polymorphism within populations. When there are no barriers to gene flow and different microhabitats result in large differences in organisms fitness, local adaptation determined by canalization of a single phenotype is a risky strategy, because there are large chances of occurring a mismatch between the phenotype produced by the organisms and the optimum phenotype for that microhabitat. Marine encrusting organisms are excellent models to test the mechanisms behind the phenotypic variation in populations, because they usually present short life cycles, are easily manipulated and are frequently exposed to a high heterogeneous habitat as a result of the human impact in coastal waters. In the littoral of São Paulo, the Yacht Clube of Ilhabela is a recreational marina formed by floating platforms surrounded by a jetty that reduces water turbulence. In this context, individuals growing inside and outside the jetty, besides living very close to each other, are exposed to different environmental conditions, what can result in different phenotypes. The objective of this study is to provide information on the diferences of physical conditions among the two areas, and access how these differences determine the diversity of predatory fishes, the recruitment of sessile organisms, predation on recruits, the organization of the sessile community and the phenotypes of the briozoan Schizoporella errata. The results obtained during this study will help to understand how large differences in physical condition in small scales can contribute to sessile community organization and to determine the fitness of S. errata. (AU)