Fishes of the Atlantic Rain Forest Streams: Ecological Patterns and Conservation

Abstract

Fishes constitute more than one half of the species of vertebrates, with around 32,000 living species (Froese & Pauly, 2011). Approximately 40% of this global fish diversity lives in freshwater environments, which represents less than 1% of the surface of the Earth (Dudgeon et al., 2006). In the Neotropical Region, freshwater fishes constitute a taxonomically distinct fauna that extends throughout the continental waters from Central Mexico to the southernmost tip of South America. This zoogeographical region is known to harbor the richest and most diverse freshwater fish fauna of the whole planet (Gery, 1969; Vari & Malabarba, 1998; Lundberg et al., 2000; Albert et al., 2011). The Atlantic Rain Forest is one of the richest biomes in the Neotropics mainly due to the variety of habitats throughout the range of the forest types and subtypes, which originally covered a wide stripe of the Brazilian coastline (Morellato & Haddad, 2000). Considering the fact that the definition of the limits and forest types of the Brazilian Atlantic Rain Forest is controversial and beyond the scope of this study, this vegetation domain was considered here in a narrower sense, comprising the coastal forest formations between 6–300 S, with elevations from sea level to approximately 1,000 meters. In this sense, this forest is dispersed along degraded landscapes, embracing some of the largest and oldest Brazilian urban areas, where more than 150 million people live. The Atlantic Rain Forest constitutes one of Brazil s most important vegetation domains, because of its historical relationship with the colonization of the country, and also in view of the role that it plays in the conservationist scenario (Silva, 2003). In the broadest and most generic sense of the forest formations, this biome is one of the most biodiverse and endangered ecosystems in the world (Myers et al., 2000). The region bounded by this forest has a high percentage of fish species with restricted distribution, as a result of the great number of independent coastal drainages (or groups of basins), and the isolating effect of mountain ranges and seawater among coastal rivers (Bizerril, 1994; Menezes et al., 2007). In fact, according to our survey a great amount (70%) of the freshwater fishes can be considered exclusive to the coastal drainages of this vegetation domain The high rate of speciation and high degree of geographic endemism is an important factor that needs to be considered in the conservation policies of the Atlantic Rain Forest remains, as this biome is located in the most populated regions of the country,