Fish Diversity and Conservation in a Neotropical Grassland Region

In this chapter, we compile information on the freshwater fish species found in the Pampa region north of the La Plata river in Brazil and Uruguay, as well as the highland grassland enclaves in the southern part of the Atlantic Forest. This geographical area encompasses seven distinct freshwater ecoregions, which exhibit a relatively low proportion of shared species. This leads to a high level of regional species diversity, comparable to other ecoregional groups of tropical South America. The grassland ecosystems of the Pampa and highland grasslands collectively host 570 freshwater fish species. Among these, 334 species are known to occur in the Pampa to which 102 (30.5% of the total) are endemic. Annual fishes (Rivulidae) are an important component of the pampean fish fauna, both because of their high species richness, estimated at around 40, and their significant contribution to the endemic fish species in the Pampa, accounting for approximately 44.1% of all endemic fish species in the region. In addition, a significant proportion of the species (27) are currently categorized as highly endangered. Environmental pressures derive mainly from land use changes, but also include drainage modifications, wetland loss, mining, species invasions and pollution. Conservation efforts aimed at protecting the fish species of the Pampa have been insufficient, albeit important initiatives such as the development of regional and national red lists of threatened species have been implemented. Existing protected areas are limited in number and cover a relatively small portion of the region. Furthermore, they do not adequately represent the diverse ecoregions and aquatic habitats found in the Pampa.