Fish biodiversity and conservation in South America

Abstract

The freshwater and marine fish faunas of South America are the most diverse on Earth, with current species richness estimates standing above 9100 species. In addition, over the last decade at least 100 species were described every year. There are currently about 5160 freshwater fish species, and the estimate for the freshwater fish fauna alone points to a final diversity between 8000 and 9000 species. South America also has c. 4000 species of marine fishes. The mega-diverse fish faunas of South America evolved over a period of >100 million years, with most lineages tracing origins to Gondwana and the adjacent Tethys Sea. This high diversity was in part maintained by escaping the mass extinctions and biotic turnovers associated with Cenozoic climate cooling, the formation of boreal and temperate zones at high latitudes and aridification in many places at equatorial latitudes. The fresh waters of the continent are divided into 13 basin complexes, large basins consolidated as a single unit plus historically connected adjacent coastal drainages, and smaller coastal basins grouped together on the basis of biogeographic criteria. Species diversity, endemism, noteworthy groups and state of knowledge of each basin complex are described. Marine habitats around South America, both coastal and oceanic, are also described in terms of fish diversity, endemism and state of knowledge. Because of extensive land use changes, hydroelectric damming, water divergence for irrigation, urbanization, sedimentation and overfishing 4-10% of all fish species in South America face some degree of extinction risk, mainly due to habitat loss and degradation. These figures suggest that the conservation status of South American freshwater fish faunas is better than in most other regions of the world, but the marine fishes are as threatened as elsewhere. Conserving the remarkable aquatic habitats and fishes of South America is a growing challenge in face of the rapid anthropogenic changes of the 21st century, and deserves attention from conservationists and policy makers.

Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

“…In addition, the region has been broadly stable for an extended period of time and has not been regularly subject to wideranging diversity-decreasing factors such as glaciations and desertification. Such historical factors imply both increased diversification rates and decreased extinction rates, resulting in extraordinary richness of the freshwater biota as seen today Reis et al, 2016).…”

Ichthyofauna of the upper Juruena river on Chapada dos Parecis, Mato Grosso, Brazil

“…The Neotropical region, that includes the South and part of Central America, harbours the most diverse freshwater fish fauna in the world including 5.400 registered species (Reis 2013), with estimates of a final number between 8.000 -9.000 species (Schaefer 1998, Reis et al 2016. Most of this ichthyofaunal diversity is located in the Amazon basin (Amazon, Orinoco and Guiana basins), in which 2.354 (Albert et al 2011) or 2.411 (Reis et al 2016) valid fish species are included.…”

“…Most of this ichthyofaunal diversity is located in the Amazon basin (Amazon, Orinoco and Guiana basins), in which 2.354 (Albert et al 2011) or 2.411 (Reis et al 2016) valid fish species are included. Most of the major tributaries of the Amazon river basin, still lack an inventory of their fish species, including the rio Tapajós.…”

A tutela jurídica da biodiversidade no Brasil e na Colômbia pós-1992:

“…Os países desse continente contam com grandes reservatórios de água (GLOBAL WATER PARTNERSHIP, 2015), diversidade de solos (RICHTER; BABBAR, 1991), extensas reservas de minérios (MILLER; STAPPENBECK; MAULL, 1927), além de fauna e flora diversificadas (BANDA et al, 2016;REIS et al, 2016). Em termos de biodiversidade, aqui compreendida como a "variabilidade de organismos de todas as origens e os complexos ecológicos de que fazem parte" (AMARAL et al, 1999, p.1) e "componente do sistema de suporte à vida de nosso planeta" (JOLY et al, 2011, p.4), a região sulamericana é a que detém o maior valor, apresentando-se "como um dos maiores centros de difusão de espécies vivas para os demais países" (VARELLA, 1997a, p.1).…”