This chapter provides an overview of biodiversity in the Amazon, discusses the reasons why this region is so rich in species and ecosystems, and outlines some outstanding ecological processes that make the Amazon an icon of the natural world. Featured terrestrial and aquatic taxonomic groups illustrate how much we know about diversity in the Amazon, and more importantly, how much we still do not know. A clear understanding of biodiversity levels and their spatial and temporal variations is crucial to understanding future stability under different climate change, land use change, forest fragmentation, and deforestation scenarios and informing conservation and restoration efforts.

Diversidad, abundancia relativa y patrones de actividad de los mamíferos medianos y grandes, asociados a los bosques riparios del río Bita, Vichada, Colombia

The dolphins Inia geoffrensis—boto and Sotalia fluviatilis—tucuxi are threatened cetaceans inhabiting river ecosystems in South America; population numbers are still lacking for many areas. This paper provides density and abundance estimations of boto and tucuxi in 15 rivers sampled during the past nine years as part of a multinational research alliance. Visual boat-survey data collection protocols and analyses have been developed since 2012 (based on Distance Sampling methods) and recently reviewed (2019) to improve robustness and comparability. Differences across the sampled rivers and the analyzed river basins (Amazon and Orinoco) pointed to a density/population size gradient with lower densities and abundances observed in the Orinoco basin (0.9–1.5 ind./km²), passing through the eastern Amazon basin (2–5 ind./km²), and the largest numbers found at the central Brazilian Amazon (lower Purus River—2012 (14.5 boto/km², N = 7672; 17.1 tucuxi/km², N = 9238)). However, in other parts of the central Amazon, the density of dolphins was smaller than expected for high productive whitewater rivers (1–1.7 ind./km² in the Japurá and Solimões rivers). We attributed these differences to specific features of the basin (e.g., hydro-geomorphology) as well as to the cumulative effects of anthropogenic activities.

Update on the freshwater distribution of Sotalia in Colombia, Ecuador, Peru, Venezuela and Suriname

The Orinoco river basin is the third largest river in the world by volume. Its catchment encompasses 27 major sub-basins including the Bita with a catchment area of about 825,000 ha, which originates in the Colombian high plains in the Llanos ecoregion. It has been recognized as a priority area for conservation through different gap analyses and overall determined to have good health according to the Orinoco report card 2016. The natural climate and hydrologic processes, and their synergies with flooded forests, savannas, wetlands, species diversity and local economic activities, are part of a dynamic and sensitive system. With the purpose of conserving the ecological, social and cultural benefits that it brings, the Colombian Government, with the support of regional and local civil society organizations, promoted the designation of a conservation area. Technical exercises were carried out including biological and socioeconomic surveys, local stakeholder consultations and future scenario modeling. In June 2018, the Bita River basin was designated as the largest Ramsar site in Colombia, providing a worldwide example of explicit protection of riverine systems. In order to maintain this free-flowing river, land use and fisheries management, in conjunction with other conservation actions, are being implemented and provide a model of protection for freshwater ecosystems that could be replicated elsewhere.

Estudiamos la diversidad de mamíferos medianos y grandes en un área no protegida de la Orinoquia Colombiana durante tres años, empleando cámaras trampa en 72 estaciones de muestreo y haciendo recorridos por bosques y sabanas. Con un esfuerzo de 1789 días-cámara y 469.5 km recorridos se documentaron 31 especies de mamíferos (9 órdenes, 19 familias). Se registraron especies amenazadas como ocarro (Priodontes maximus), danta (Tapirus terrestris), pecarí de labio blanco (Tayassu pecari) y hormiguero gigante (Myrmecophaga tridactyla). Se registraron especies raras, como el perro vinagre (Speothos venaticus) y semiendémicas como el cachicamo sabanero (Dasypus sabanicola). Las especies mejor representadas a través del índice de abundancia relativa fueron el pecarí de collar (Pecari tajacu) y la zarigüeya (Didelphis marsupialis). Las especies registradas se enfrentan a diversas presiones, como cacería para subsistencia, especies invasoras y ganadería. Por lo tanto, los resultados sugieren que las áreas no protegidas son importantes para la conservación de los mamíferos en los Llanos Orientales de Colombia.