Fishes of the Amazon: diversity and beyond

Abstract

The Amazon basin houses a particular group of freshwater organisms, whose study tells the geological history of the region, how biological diversity was shaped, how it is maintained, and what it hides. The fish of the Amazon is represented by more than 3,000 known species distributed from the basal groups up to the more specialized ones. This species richness hides a diversity of adaptations that are dispersed at all levels of the biological organization. In this summary of the conference delivered at the Brazil-France Bilateral Symposium, held in Manaus in 2018, we describe two aspects of the hidden world of adaptive diversity: adaptations to changes in dissolved oxygen and the abilities of the Rio Negro fish to face acidic and ion-poor waters of their habitats. Also, we present the vulnerability of Amazonian fish to ongoing climate changes. Then, very briefly, we call attention to the many hidden biological processes that allow these fish species to survive their environments, much of which is unknown. Indeed, however, they are intricately related to men, either by responding to environmental disturbances that we have caused, or by containing information that contributes to improving the quality of the environment in which we live.

Distribution patterns of Procamallanus (Spirocamallanus) inopinatus (Nematoda: Camallanidae) and its interactions with freshwater fish in Brazil

“…intestine, stomach, pyloric caecum and abdominal cavity) in the same population of fish, with different levels of infection together and with an aggregated dispersion pattern, seems allow coexistence of parasite species that would be excluded. Therefore, these findings corroborate the suggestion that the levels of different parasites shared by the same host may favor coexistence of more species of parasites, since large phylogenetic differences allow potentially competing parasites to consume the same resources without being sensitive to other parasite species (Geets & Ollevier, 1996;Bellay et al, 2013;Bhuiyan et al, 2014;Salgado-Maldonado et al, 2016, 2019. The findings from the present study are in line with this, because in most of the parasite-host systems investigated here, the gastrointestinal tract was the site most frequently infected by P. (S.) inopinatus.…”

“…In addition, variations in the levels of endohelminth infection are, in general, strongly dependent on the population densities of intermediate and definitive hosts, overlapping in time and space in the same ecosystem (Blasco-Costa et al, 2015). It is also important to highlight that we analyzed host fish from different Brazilian hydrographic basin systems, which are environments with different dynamics due to the diverse characteristics of their water (Agostinho et al, 2005;Brasil, 2006;Takemoto et al, 2009;Barletta et al, 2010;Carvalho & Albert, 2011;Junk, 2013;Val, 2019). These characteristics strongly influence the invertebrate and fish communities that are intermediate and definitive hosts for P. (S.) inopinatus, respectively.…”

The shadow of the Balbina dam: A synthesis of over 35 years of downstream impacts on floodplain forests in Central Amazonia

“…Tree species have adapted to the hydrological cycles over evolutionary time scales by developing and combining morphoanatomic, physiological, and biochemical mechanisms to cope with the anoxic conditions induced by flooding (De Simone et al, 2002;Haase & Rätsch, 2010;Junk, 1989;Parolin et al, 2004;Piedade, Ferreira, Oliveira Wittmann, Buckeride, & Parolin, 2010). This also holds true for the aquatic fauna, such as fishes (Val, 2019) and invertebrates (Adis, 2010).…”

Ichthyofauna of sandy beaches along the Acre river, Brazil

“…The fish fauna found in these environments is very diverse (Goulding 1997, Lowe-McConnell 1999, Py-Daniel et al 2007, Duarte et al 2010, composed mainly of small species with diverse feeding habits and reproductive strategies. This enormous diversity of species is linked to several evolutionary factors, including the formation of the drainage basins, hydrological dynamics, environmental heterogeneity, and flood and reflux pulses (Val 2019).…”

“…The Acre river is a medium-sized watercourse, by the standards of the Amazon basin, running 1190 km from its source, in Peru, to its confluence with the Purus river in the Brazilian state of Amazonas, first passing through Bolivia and then the state of Acre, Brazil. Ichthyological research in Acre has included studies on the Juruá river (Silvano et al 2001) and the middle Purus (Dos Anjos et al 2008), as well as studies of the streams (Claro-García et al 2013, Corrêa et al 2018, Virgilio et al 2018, 2019 and lakes (da Silva et al 2013) of the Acre basin.…”