Conservation of Amazonian aquatic mammals

Abstract

Aquatic mammals worldwide are highly threatened in freshwater ecosystems where they are affected by direct human activities (e.g. hunting) as well as indirect human alteration of freshwater ecosystems (e.g. dams, mining activity). Although aquatic mammals of the Amazon Basin are experiencing many growing threats, little is known about the escalating impacts on them, current limitations in protection mechanisms, and possible strategies to ensure their conservation. This study synthesizes the available information on Amazonian aquatic mammals, including the ecological characteristics of these species, key threats, population status and conservation prospects. Amazonian aquatic mammals comprise seven species – Inia geoffrensis, Inia boliviensis, Inia araguaiaensis, Sotalia fluviatilis, Trichechus inunguis, Pteronura brasiliensis and Lontra longicaudis – which are characterized by low reproductive rates and keystone ecosystem roles. These species are endangered mainly by biological resource use, natural ecosystem modifications, energy production and mining, and climate change. Although information is sparse, there is evidence that these threats are inducing population declines of Inia spp., and hindering the recovery of populations of P. brasiliensis. Protection mechanisms for these species mostly include national and international laws and agreements, legislation governing environmental licensing and protected areas. Each of these protection mechanisms, however, has limited capacity to protect Amazonian aquatic mammals, largely because they are poorly enforced, lack transnational coordination or require population trend data that do not exist. Reversing the current state of affairs for Amazonian aquatic mammals requires an integrated research and policy approach that, at a minimum, substantially increases the present capacity to monitor their population responses to human impacts, establishes effective enforcement of existing legislation and prevents further impacts from hydropower development. To implement such an approach, information on the ecology of these species is necessary to create public and scientific awareness.

Reconstructing the historical distribution and local extinction of the giant otter Pteronura brasiliensis in the Atlantic Forest of South America

“…The extensive construction of dams for hydropower generation, especially in São Paulo and Paraná states, has been the cause of decline and extinction of fish populations in the Atlantic Forest, the main source of food for giant otters (Fahey & Langhammer, 2003; Agostinho, Pelicice & Gomes, 2008). Empirical studies show that, in Amazonia, these artificial lakes are able to maintain populations of giant otters, although smaller than the pre‐flooding ones (Rosas, Mattos & Mendes Cabral, 2007; Palmeirim, Peres & Rosas, 2014; Calaça, Faedo & Melo, 2015; Brum et al, 2021). However, the major impacts of dams on giant otters are the habitat alterations caused during the construction and post‐filling phases, which reduce forest cover and den availability along river banks (Lima, Marmontel & Bernard, 2012; Palmeirim, Peres & Rosas, 2014).…”

Spatio‐temporal, ontogenetic and sex‐related patterns in resource use of Amazonian manatees across floodplains and estuaries as inferred by δ13C and δ15N isotopic values

“…Many factors combined or in isolation may lead to adverse and cumulative effects on populations and ecosystems, emphasizing the importance of identifying them and understanding the complexity of their interactions. The Amazonian manatee ( Trichechus inunguis ), an endemic sirenian of the Amazon Blasin, is mainly threatened by hunting (Calvimontes, 2009; Crema, da Silva & Piedade, 2019) and modifications of the natural system by human activities (Brum et al, 2021). The species is currently listed as Vulnerable in the IUCN Red List (Marmontel, de Souza & Kendall, 2016) and in the Brazilian National List of Endangered Species (MMA, 2014) and is also included in Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).…”

Impacts of dams on freshwater turtles: a global review to identify conservation solutions

“…Species that inhabit freshwater ecosystems are vulnerable to extinction due to dams impacts (Brum et al, 2021; Dudgeon, 2019; Tickner et al, 2020), as their life history and biological schedules often strongly depend on the hydrological regime (Zarfl et al, 2019). Although populations of freshwater vertebrate species have declined at more than twice the rate of terrestrial or marine vertebrates (Grooten and Almond, 2018; Tickner et al, 2020), relatively few studies have evaluated the impact of dams on vertebrates (dos Santos et al, 2021; He et al, 2018).…”