The Avifauna of the Rio Branco, an Amazonian evolutionary and ecological hotspot in peril

Naka, Luciano N.; Laranjeiras, Thiago Orsi; Lima, Gisiane Rodrigues; Plaskievicz, Alice C.; Mariz, Daniele; Costa, Bruna M. da Silva; Menezes, H. Suzany G. De; Torres, Marcela De Fátima; Cohn‐Haft, Mario

doi:10.1017/s0959270919000133

Cited by 13 publications

(34 citation statements)

References 40 publications

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“…We systematically distributed these surveys throughout the entire length of the Rio Branco and its two main tributaries, the Uraricoera and Tacutu rivers. In a previous study (Naka et al, 2020), we have shown that geomorphology can explain differences in species composition between the upper and lower sections of the Rio Branco. Here, we ask how the environmental gradient present on top of these geomorphologic units affects taxonomic and phylogenetic alpha and beta avian diversities along the river.…”

Section: Introductionmentioning

confidence: 82%

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Climate as a major driver of avian diversity in riparian Amazonian habitats along an environmental gradient

Naka

Laranjeiras

Lima

et al. 2020

Journal of Biogeography

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Aim: To investigate the influence of bioclimatic, productivity and topographic variables on avian diversity patterns in riparian habitats along a savanna/humid forest environmental gradient. We investigate how this gradient affects patterns of taxonomic and phylogenetic alpha and beta diversities, and whether the changes observed along the river are the result of taxonomic (and phylogenetic) replacement or nestednessresultant dissimilarities. We also explore a potential ecological mechanism to account for differences in species richness along the gradient. Location: Basin of the Rio Branco, northern Amazonia, Brazil. Taxa: An avian community of 325 bird species. Methods: We sampled avian communities using standardized avian point counts at 16 localities, systematically distributed along the Rio Branco and two of its major tributaries. We compared patterns of species richness using rarefied numbers of species detected, and patterns of phylogenetic diversity with a community-wide consensus tree. In addition, we partitioned beta diversity in species replacement and nestedness-resultant dissimilarities. We reduced predictor variables using a principal components analysis, correlating locality scores with changes in diversity. We tested the effect of climatic variables on beta diversity with a distance-based redundancy analysis (dbRDA). Results: Patterns of avian composition and species richness were highly correlated with climatic and productivity variables. We found more bird species in less arid localities with higher annual precipitation, and in areas with lower annual temperatures, lower evapotranspiration and less temperature variation throughout the year. Despite differences in species richness, the number of individuals remained relatively similar along the gradient. However, species-rich localities presented lower average species frequency and median avian biomass. Patterns of taxonomic and phylogenetic beta diversity were correlated with the climatic gradient and were due to species replacements. Main conclusions: Climate represents a major player in structuring avian communities along the Rio Branco, affecting distinct levels of avian diversity organization. We found evidence of species packing, a mechanism to fit more species in the communities. Patterns of species replacement highlight the importance of transitional zones | 2329 NAKA et Al.

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Section: Introductionmentioning

confidence: 82%

“…To date, a total of 439 bird species have been recorded in riverine habitats along this river and its main tributaries (Naka et al, 2020).…”

Section: The Avifauna Of the Rio Brancomentioning

confidence: 99%

Climate as a major driver of avian diversity in riparian Amazonian habitats along an environmental gradient

Naka

Laranjeiras

Lima

et al. 2020

Journal of Biogeography

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“…The flooded forest and fauna of the Negro River basin are vulnerable to changes in the hydrological system, whether of climatic origin (El Niño/La Niña) or due to the construction of a hydropower dams [38,39]. The regulation of water flows and sediment discharge on the Branco River by the Bem Querer dam and other tributaries in the basin will reduce the amount of sediments that arrive in the Anavilhanas as it was previewed for other areas in the Amazon basin [27,28].…”

Section: Impacts Of the Branco River Hydropower Dams On The Fluvial Ementioning

confidence: 99%

“…Currently, the four hydroelectric plants planned for the Branco River, together with the easing of environmental licensing and weakening of regulatory agencies are the main threats in the Negro River basin [38,75,76], especially on the Anavilhanas Archipelago. Currently, studies to evaluate the impacts of dams in the Brazilian Amazon mainly consider the area directly affected.…”

Section: Impacts Of the Branco River Hydropower Dams On The Fluvial Ementioning

confidence: 99%

Analysis of Suspended Sediment in the Anavilhanas Archipelago, Rio Negro, Amazon Basin

Marinho

Filizola

Cremon

2020

Water

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This article analyzes the flows of water and total suspended sediment in different reaches in the lower course of the Negro River, the largest fluvial blackwater system in the world. The area under study is the Anavilhanas Archipelago, which is a complex multichannel reach on the Negro River. Between the years 2016 and 2019, data about water discharge, velocity, and concentration of total suspended solids (TSS) were acquired in sample sections of the Negro River channels located upstream, inside, and downstream of the Anavilhanas Archipelago. In the study area, the Negro River drains an area greater than 700,000 km2, and the mean water discharge observed before the Anavilhanas was about 28.655 m3·s−1, of which 97% flows through two channels of the Archipelago close to the right and left banks. The mean TSS concentration of the Negro River upstream and downstream the Archipelago was 3.28 mg·L−1 and 1.63 mg·L−1, respectively. Within the Archipelago, we observed more TSS in the channel on the left bank of the Negro River (mean of 4.50 mg·L−1). The total suspended sediment discharge of the Negro River before (3.14 Mt·year−1) and after (1.43 Mt·year−1) the Anavilhanas Archipelago indicates a 55% retention of the suspended load due to the low water slope and reduced flow velocity caused by the backwater effect of Solimões River on the Negro River. The hydro-sedimentary scenario of the low course of the Negro River characterized in this study indicates a slow and continuous sedimentation process in the Anavilhanas Archipelago. The results presented will serve as a baseline to assess the impacts of the dams on the Branco River, the main tributary for both water and sediment in the Negro River basin.

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“…These somewhat muddy rivers in the Rio Negro basin contrast visibly with the nearby typical blackwater rivers and offer an opportunity to test the effect of river type on the floodplain avifauna. The largest Rio Negro tributary, the Rio Branco, contains isolated populations of some bird species found primarily in other whitewater rivers in the main Amazon–Madeira river system, which are absent from the Rio Negro itself (Laranjeiras et al., ; Naka, Cohn‐Haft, Whittaker, Barnett, & Torres, ; Naka et al., in press). Most of the tributaries within the Rio Negro basin, however, lacked prior avian surveys, making fieldwork crucial to careful comparisons.…”

Section: Introductionmentioning

confidence: 99%

Using river color to predict Amazonian floodplain forest avifaunas in the world's largest blackwater river basin

2019

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| INTRODUC TI ONOne of Amazonia's most striking features is the diversity of "colors" of its many rivers. The distinction between white-, black-, and clearwater rivers was recognized by early naturalists in the Amazon basin (e.g., Wallace, 1853; Holdridge, 1933) and long before them in the very names of the rivers, such as "Rio Negro" and "Rio Branco." River "color" (i.e., river type; hereafter used interchangeably) classification is based on the color and other physical and chemical parameters of the water, which in turn are related to the geomorphology of the river's catchment region (Sioli, 1968;Janzen, 1974). Turbid and nutrient-rich whitewater rivers (e.g., Rio Madeira) mostly drain the Abstract Despite the importance of rivers in Amazonian biogeography, avian distribution patterns in river-created habitats (i.e., floodplain forests) have been sparsely addressed.Here, we explore geographic variation in floodplain forest avifaunas, specifically regarding one of the most striking aspects of the Amazon: the diversity of river "colors" (i.e., types, based on the color of the water). We sampled the avifauna at 30 sites, located in 17 different rivers (nine black-and eight whitewater), in the Rio Negro basin, northwestern Brazil. Our sampling comprised ten 15-min point-counts per site, distributed every 500-1000 m along the river. We recorded a total of 352 bird species, many of which occurred in both river types. Although bird species richness was similar among rivers, we found significant differences in species composition. Nearly 14 percent of the species were significantly associated with one or the other river type. Most floodplain forest specialists occurred predominantly in whitewater rivers, whereas species that are typically associated with white-sand habitats occurred in blackwater. Despite significant distinctions between river types, occurrence patterns and levels of habitat association differed among indicator species and may vary in the same species throughout its global distribution. There were also "intermediate" avifauna in some of our sites, suggesting that continuous parameters characterizing river types structure species turnover. The water color-based classification of Amazonian rivers represents a simple and powerful predictor of the floodplain forest avifauna, offering a stimulating starting point for understanding patterns of floodplain bird distributions and for prioritizing conservation efforts in these overlooked habitats.Abstract in Portuguese is available with online material. K E Y

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The Avifauna of the Rio Branco, an Amazonian evolutionary and ecological hotspot in peril

Cited by 13 publications

References 40 publications

Climate as a major driver of avian diversity in riparian Amazonian habitats along an environmental gradient

Climate as a major driver of avian diversity in riparian Amazonian habitats along an environmental gradient

Analysis of Suspended Sediment in the Anavilhanas Archipelago, Rio Negro, Amazon Basin

Using river color to predict Amazonian floodplain forest avifaunas in the world's largest blackwater river basin

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