Population dynamics of Amazonian floodplain forest species support spatial variation on genetic diversity but not range expansions through time

Aim: We tested if historical demographic changes of populations occurring on the floodplains of a major Amazon Basin tributary could be associated with range expansions from upper and middle sections of the river, following the establishment of widespread river-created environments during the Late Pleistocene and Holocene. Location: Solimoes River, Western Amazon, South America Taxon: Myrmoborus lugubris, Thamnophilus cryptoleucus and Myrmotherula assimilis Methods: We analyzed thousands of UltraConserved Elements to explore spatial patterns of genetic diversity and connectivity between individuals. Range expansions were tested with alternative methods. We quantified habitat preference for the analyzed species in order to test if the occupation of dynamic habitats could predict spatial patterns of genetic diversity. Results: Our study did not support shared population range expansions related to historical regionalized changes in habitat availability. We found considerable variation in the spatial distribution of the genetic diversity between studied taxa, and that species with higher levels of specialization to dynamic environments have a more heterogeneous distribution of genetic diversity and reduced levels of gene flow across space. Main conclusions: Our results suggest that demographic expansions along the Solimoes River might be linked to geographic homogeneous oscillation in the distribution of floodplain environments, promoting effective population size changes but not range expansion. We found that habitat specificity might be a good predictor of population connectivity along the Amazonian floodplains.

Selectivity and efficiency of herbicides in cassava on the floodplain of the Solimões river

Cassava is grown on the floodplains of the Solimões river and guarantees food security and income for farmers. However, negative interference of weeds can result in a significant yield loss in the crop. Therefore, the aim of this study was to evaluate the selectivity of herbicides and efficiency of chemical weed control in the cassava ‘Aipim-manteiga’ cultivar, in the floodplain of the Solimões river, in Iranduba, Amazonas. The experimental design was in randomized blocks with four replications. The herbicides evaluated were clomazone (1080 g ha-1), diuron (1750 and 2500 g ha-1) and oxadiazon (400 and 800 g ha-1), applied alone or with hoeing 90 days after planting (DAP). Two control treatments were included: weeding (hoeing) at 30, 60, 90 and 120 DAP and with no weed control. Clomazone caused mild toxicity in the plants, while with diuron and oxadiazon toxicity was moderate; all three were considered safe for the crop. The plant population of the crop was not affected by the herbicides. Clomazone afforded effective weed control up to 45 DAP only, and weeding was necessary at 90 DAP to eliminate negative interference by the weeds on crop yield. Diuron and oxadiazon were effective in controlling weeds throughout the crop cycle of the cassava. Weed interference during the crop life cicle reduced yield by 83.8%.

CONDITIONING FACTORS OF “TERRAS CAÍDAS” IN LOWER SOLIMÕES RIVER - BRAZIL

The term “Terras Caídas” is used in Amazon to refer to processes of fluvial erosion and mass movements of large and moderate scale. It is a dynamic and complex multi-causal process that involves hydrodynamic, hydrostatic, climatic, neotectonic, lithological and anthropic factors, occurring together or separately. The objective of this work is to understand the conditioning factors of the phenomenon "Terras Caídas" in lower Solimões River - Brazil. For this purpose, the study area was monitored for 2 years (2017-2018) and data from satellite images; water discharge; flow velocity; suspended sediments; water level; precipitation; wind direction; seismic activity were obtained. The hydrodynamic factors and the rain influence the “Terras Caídas” more intensely during the river flood, the processes influenced by the wind direction occur throughout the hydrological year, but with greater intensity during storms. Hydrostatic pressure occurs more frequently in ebb causing landslides. The lithology influences the stability of the banks due to unconsolidated sediments, providing erosion and mass movements. It is observed that neotectonics was not important in increasing the intensity of the "Terras Caídas" in the study area in recent years. Human activity influences destroying riparian forests and the basal erosion caused by waves formed by boats the region.

CONTEMPLAÇÃO NAS SOMBRAS: O GUESA DE SOUSÂNDRADE E A MEIA-NOITE ÀS MARGENS DO SOLIMÕES

This article aims to analyze the episode that narrates the Guesa's midnight dream on the banks of the Solimões River, a passage that is present in the first book of Joaquim de Sousândrade's pan-Indian epic O Guesa. This part, which anticipates the epic topic of the “descent into hell” that occurs during the Dance of Tatuturema in the second book, shows some of the literary influences over the poet's voice in formal and thematic aspects. This study will try to identify, through the poetic text, some of these influences, quite varied and assembling aspects of epic poetry - classical, renaissance and modern - of lyric and of romantic and Indianist literature, culminating in an object of singular value within Brazilian poetry. Guesa, a Muisca Indian, personification of the Sun-god and representative of the pan-Indian project of Sousândrade, undergoes a metamorphosis at midnight: he resembles Lucifer and Prometheus, and sings his melancholy just like Baudelaire on the banks of the mythical Lethe.

Length-weight relationships of ornamental fish from floodplain lakes in the Solimões River basin (Iranduba, Amazonas, Brazil)

This research reports the LWR of ornamental fish from floodplain lakes of the Solimões River basin. The fish were caught in the Paciência island (a fluvial island) in two lakes Sacambú and Cacau using purse seine 7 m × 4 m and mesh size = 3 mm, once during the flood in June 2017 and dry in January 2018. The specimens captured were anesthetized using eugenol 15 mg · L–1, fixed formalin 10% and stored ethanol 70% after 10 days. This study provides the LWR parameters for the species Anablepsoides micropus, Anchoviella jamesi, Cichlasoma amazonarum, Heros efasciatus, Ctenobrycon hauxwellianus, Copella nattereri and Hemigrammus levis. The parameter a ranged from 0.0092 to 0.0229, b ranged from 2.78 to 3.50 and the R2 ranged from 0.985 to 0.998. The results represent new information about ornamental fish from floodplain lakes, with new LWR for five species that are not present in FishBase data set and probably are new for science. This study is preliminary and much work needs to be done especially in the Solimões River floodplain areas and with our research we hope to encourage new studies in the region.

Suspended Sediment Variability at the Solimões and Negro Confluence between May 2013 and February 2014

This study focuses on the confluence of two major rivers of the world, the Solimões River (white waters) and Negro River (black waters). Surface suspended sediment samples (SSC) and spectroradiometer taken along transverse profiles at 500 m intervals over a distance of 10 km, as well as satellite images (MODIS) during the hydrological year, were used to follow suspended sediment variability. In January and February, the confluence is dominated by white waters from the Solimões River in the two banks, and in June and July in the right bank by black waters from the Negro River and in the left bank by clear waters from the Solimões River. We found that indirect tools, such as reflectance obtained by spectrometer or MODIS images, can be used to determine surface suspended sediments in a contrasting zone.