RANGE EXPANSION OF Sakesphorus canadensis loretoyacuensis (AVES: THAMNOPHILIDAE) TOWARDS THE YAGUAS RIVER, LORETO, PERU

The role of abrupt climate change in the formation of an open vegetation enclave in northern Amazonia during the late Quaternary

Large rivers, slow drainage rearrangements: The ongoing fluvial piracy of a major river by its tributary in the Branco River Basin - Northern Amazon

This study reports for the first time, the Hg concentrations in the fish fauna of the Tartarugalzinho river basin — an important gold mining region in Amapa State, Northern Amazon — and evaluates human exposure to Hg due to fish consumption in the area. We analyzed 16 fish species (carnivorous and omnivorous) common in the aquatic environment of the Tartarugalzinho area and which are mostly consumed by the local population. Mercury concentrations in fish ranged from 35 μg.kg−1 to 1,225 μg.kg−1 . Among the analyzed fish, 8 species (50%) presented Hg concentrations higher than 500 μg.kg−1, the U.S. Food and Drug Administration (FDA) Action Level for concentration of Hg in fish. No statistical difference was observed between Hg mean concentrations in carnivorous and omnivorous fish. Within a given species, Hg concentrations were positively correlated with fish size or weight. The Hg concentration ratio between fish and water showed values higher than 50,000. Human exposure was estimated through the daily Hg intake obtained through interviews with the local population on the amount and species of fish consumed and the Hg concentration in the fish. The estimated average daily intake was 114 μg.day−1. This amount is approximately one-half of the WHO recommended provisional tolerable Hg weekly intake. At screening level, it assumes that there is a level of exposure (e.g, USEPA's RfD = Reference of Dose) below which it is unlikely for even sensitive populations to experience adverse health effects. The estimated exposure level for adult humans (1.6 μg.kg−1.day−1) was nearly 5 times greater than Hg RfD (0.3 μg.kg1.day−1). The results suggest a widespread Hg contamination in the local fish fauna. Due to high fish Hg concentrations and high fish intake by local population, environmental exposure to Hg is also high, presenting a health risk to population.

This study reports for the first time, the Hg concentrations in the fish fauna of the Tartarugalzinho river basin — an important gold mining region in Amapa State, Northern Amazon — and evaluates human exposure to Hg due to fish consumption in the area. We analyzed 16 fish species (carnivorous and omnivorous) common in the aquatic environment of the Tartarugalzinho area and which are mostly consumed by the local population. Mercury concentrations in fish ranged from 35 μg.kg-1 to 1,225 μg.kg-1. Among the analyzed fish, 8 species (50%) presented Hg concentrations higher than 500 μg.kg-1, the U.S. Food and Drug Administration (FDA) Action Level for concentration of Hg in fish. No statistical difference was observed between Hg mean concentrations in carnivorous and omnivorous fish. Within a given species, Hg concentrations were positively correlated with fish size or weight. The Hg concentration ratio between fish and water showed values higher than 50,000. Human exposure was estimated through the daily Hg intake obtained through interviews with the local population on the amount and species of fish consumed and the Hg concentration in the fish. The estimated average daily intake was 114 μg.day-1. This amount is approximately one-half of the WHO recommended provisional tolerable Hg weekly intake. At screening level, it assumes that there is a level of exposure (e.g, USEPA’s RfD = Reference of Dose) below which it is unlikely for even sensitive populations to experience adverse health effects. The estimated exposure level for adult humans (1.6 μg.kg-1.day-1) was nearly 5 times greater than Hg RfD (0.3 μg.kg-1.day-1). The results suggest a widespread Hg contamination in the local fish fauna. Due to high fish Hg concentrations and high fish intake by local population, environmental exposure to Hg is also high, presenting a health risk to population.

Aim To reconstruct the biogeographical history of New World emballonurid bats (tribe Diclidurini). Although bats are the second most species‐rich order of mammals, they have not contributed substantially to our understanding of the historical biogeography of mammals in the Neotropics because of a poor fossil record. In addition, being the only group of mammals that fly, bats typically have large distributions with relatively few species endemic to restricted areas that are amenable to vicariant biogeographical approaches.Location Central and South America.Methods Phylogenetic analysis for comparing trees (PACT) is a new algorithm that incorporates all spatial information from taxon area cladograms into a general area cladogram. There were nine biogeographical areas identified in Central and South America for New World emballonurid bats. Molecular dating was used to incorporate the temporal aspect of historical biogeography. This method was compared with dispersal–vicariance analysis (DIVA), which assumes vicariance as the default mode of speciation.Results Of the 45 speciation events in a fully resolved phylogeny, eight that were hypothesized by DIVA as vicariance were considered by PACT as two peripheral isolations and six within‐area events. DIVA was less parsimonious because it required six more post‐speciation dispersal events in addition to the 73 hypothesized by PACT. DIVA reconstructed a widely distributed ancestor, suggesting that most dispersal events occurred earlier, whereas the ancestral area for PACT based on character optimization was the Northern Amazon, suggesting that dispersal events were more recent phenomena.Main conclusions The general area cladogram from PACT indicated that within‐area events, and not vicariance, provide the major mode of speciation for New World emballonurid bats. There was no biological evidence supporting or rejecting sympatric speciation in New World emballonurid bats. However, the geological history, combined with fluctuations in temperature and sea level, suggested within‐area speciation in a changing and heterogeneous environment in the Northern Amazon during the Miocene. This scenario is similar to the taxon‐pulse hypothesis of biotic diversification, which posits repeated episodes of range expansions and contractions from a stable core area such as the Guiana Shield within the Northern Amazon.

In 2023, most parts of the world experienced exceptional heat. In particular, anomalous warm temperatures and heatwave events were evidenced across South America during the second half of the year. The situation was particularly critical in the Amazon region in terms of not only hydrometeorological drought but also ecological and socioeconomic impacts. In this study, remote-sensing data collected from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used to observe the changes in temperature and vegetation across Amazonia during the exceptional drought of 2023. This analysis was based on anomalies in the land surface temperature (LST) and vegetation indices: the enhanced vegetation index (EVI) and the normalized difference vegetation index (NDVI). The amplitude of the LST (AMP-LST), an indicator of the energy partitioning between the latent and sensible heat flux, and fire counts were also considered. The results show widespread and extreme warming across Amazonia during the austral spring in 2023, accompanied by a decline in vegetation greenness, water stress conditions across northern Amazonia, and an enhanced fire occurrence across central and northern Amazonia.

Anopheline specimens were collected in 2011 by human landing catch, Shannon and CDC traps from the malaria endemic localities of Santa Rosa and San Pedro in Madre de Dios Department, Peru. Most specimens were either Anopheles (Nyssorhynchus) benarrochi B or An. (Nys.) rangeli, confirmed by polymerase chain reaction-restriction fragment length polymorphism-internal transcribed spacer 2 (PCR-RFLP-ITS2) and, for selected individuals, ITS2 sequences. A few specimens from Lupuna, Loreto Department, northern Amazonian Peru, were also identified as An. benarrochi B. A statistical parsimony network using ITS2 sequences confirmed that all Peruvian An. benarrochi B analyzed were identical to those in GenBank from Putumayo, southern Colombia. Sequences of the mtDNA COI BOLD region of specimens from all three Peruvian localities were connected using a statistical parsimony network, although there were multiple mutation steps between northern and southern Peruvian sequences. A Bayesian inference of concatenated Peruvian sequences of ITS2 + COI detected a single clade with very high support for all An. benarrochi B except one individual from Lupuna that was excluded. No samples were positive for Plasmodium by CytB-PCR.

Suture zones represent natural forums in which to examine the role of geography and ecology in the speciation process. Here, we conduct a comparative analysis designed to investigate the location of avian phylogeographic breaks and contact zones in the Guiana Shield, northern Amazonia. We use distributional and genetic data from 78 pairs of avian taxa to address whether phylogeographic breaks and contact zones are associated with contemporary landscape features. Using spatially explicit statistical models, we found that phylogeographic breaks and contact zones are not randomly distributed throughout the landscape. In general, geographic breaks cluster along physical barriers (rivers, nonforested habitats, and small mountain ranges), whereas contact zones aggregate where these barriers either break down or are easier to overcome, such as around rivers' headwaters. Our results indicate that although major Amazonian rivers are often key determinants of taxon boundaries, the "riverine barrier effect" is a synergistic consequence of the wide lower reaches of some rivers, coupled with nonriverine landscape features at the headwaters. Our data suggest that ancestral refugia are not necessary to explain current distribution patterns and that pairs of codistributed taxa do not seem to be the result of simultaneous diversification processes.

The South Atlantic Ocean Dipole (SAOD) exerts strong influence on climate variability in parts of Africa and South America. Here we assess the ability of an ensemble of 35 state-of-the-art coupled global climate models to simulate the SAOD impacts on regional rainfall for the historical period (1950–2014), and their future projections (2015–2079). For both periods we consider the peak phase of the dipole in austral winter. Observational analysis reveals four regions with spatially coherent SAOD impacts on rainfall; Northern Amazon, Guinea Coast, Central Africa, and Southeast Brazil. The observed rainfall response to the SAOD over Northern Amazon (0.31 mm d−1), Guinea Coast (0.38 mm d−1), and Southeast Brazil (0.12 mm d−1) are significantly underestimated by the modeled ensemble-mean response of 0.10 ± 0.15 mm d−1, 0.05 ± 0.15 mm d−1, −0.01 ± 0.04 mm d−1, respectively. A too southerly rain belt in the ensemble, associated with warmer-than-observed Atlantic cold tongue, leads to better performance of models over Central Africa (46% simulate observations-consistent SAOD-rainfall correlations) and poor performance over the Guinea Coast (only 5.7% simulate observations-consistent SAOD-rainfall correlations). We also find divergent responses among the projections of ensemble members precluding a categorical statement on the future strength of the SAOD-rainfall relationship in a high-emissions scenario. Our results highlight key uncertainties that must be addressed to enhance the value of SAOD-rainfall projections for the affected African and South American countries.

Rainfall variability in the Amazon basin is studied in relation to sea‐surface temperatures (SSTs) in the equatorial Pacific and the northern and southern tropical Atlantic during the 1977–99 period, using the HiBAm original rainfall data set and complementary cluster and composite analyses.The northeastern part of the basin, north of 5 °S and east of 60 °W, is significantly related with tropical SSTs: a rainier wet season is observed when the equatorial Pacific and the northern (southern) tropical Atlantic are anomalously cold (warm). A shorter and drier wet season is observed during El Niño events and negative rainfall anomalies are also significantly associated with a warm northern Atlantic in the austral autumn and a cold southern Atlantic in the spring. The northeastern Amazon rainfall anomalies are closely related with El Niño–southern oscillation during the whole year, whereas the relationships with the tropical Atlantic SST anomalies are mainly observed during the autumn. A time–space continuity is observed between El Niño‐related rainfall anomalies in the northeastern Amazon, those in the northern Amazon and south‐eastern Amazon, and those in northern South America and in the Nordeste of Brazil.A reinforcement of certain rainfall anomalies is observed when specific oceanic events combine. For instance, when El Niño and cold SSTs in the southern Atlantic are associated, very strong negative anomalies are observed in the whole northern Amazon basin. Nonetheless, the comparison of the cluster and the composite analyses results shows that the rainfall anomalies in the northeastern Amazon are not always associated with tropical SST anomalies.In the southern and western Amazon, significant tropical SST‐related rainfall anomalies are very few and spatially variable. The precipitation origins differ from those of the northeastern Amazon: land temperature variability, extratropical perturbations and moisture advection are important rainfall factors, as well as SSTs. This could partially explain why: (a) the above‐mentioned signals weaken or disappear, with the exception of the relative dryness that is observed at the peak of an El Niño event and during the dry season when northern Atlantic SSTs are warmer than usual; (b) rainfall anomalies tend to resemble those of southeastern South America, noticeably at the beginning and the end of El Niño and La Niña events; (c) some strong excesses of rain are not associated with any SST anomalies and merit further investigation. Copyright © 2002 Royal Meteorological Society.

The average annual precipitation in the Pacific coast of Colombia ranges from 8,000 to 13,000 mm. The annual average (1960-2018) in Puerto López (Cauca) rain gauge (77°14’56.3”W, 2°50’43.0”N) is 13.159 mm making it, probably, the rainiest place on the Earth. Such a large amount of precipitation also means a sizeable diabatic heating source over western Colombia, which is responsible for driving the circulation in northern South America and Mesoamerica from mid-March to the end of November. We applied a simple conceptual model to study the heat-induced circulation. Our results indicated that the heating source over western Colombia produces a steady, low-level westerly inflow as a result of a half planetary wave propagating over Mesoamerica and the far eastern Pacific that generates two cyclonical flows. On the east side of the heating source, a Kelvin wave generates a low-level easterly flow from the tropical Atlantic Ocean and the Northern Amazon and Orinoco basins in a Walker-type circulation. This Rossby and Kelvin patterns create information pathways, which, in their turn, dominate the low- and upper-level wind fields. Documented observations about the atmosphere’s general circulation over northern South America and Mesoamérica are consistent enough to support the assertion that a set of waves trapped in the tropics induced by a heating source explains the circulation over Colombia and its surroundings.

Levels of Arsenic, Cadmium, and Mercury in Urine of Indigenous People Living Close to Oil Extraction Areas in the Peruvian Amazon.

Badister (Badister) amazonus sp. n. is described from Perú, Loreto, 1.0 km SW Boca del Rio Samiria, Vigilante Post 1, 130m, “04°40.5'S, 074°18.9'W" its type locality. It is known also from two other localities in Loreto Department, Perú, in both the Varzea and Igapó river systems. This new species is sufficiently different that a new informal higher taxon, the amazonus species complex, is recognized. An updated key to the Western Hemisphere species of subgenus Badister is provided.

Epidemic malaria has rapidly emerged in Loreto Department, in the Peruvian Amazon region. Peru reports the second highest number of malaria cases in South America (after Brazil), most from Loreto. From 1992 to 1997, malaria increased 50-fold in Loreto but only fourfold in Peru. Plasmodium falciparum infection, which has increased at a faster rate than P. vivax infection in the last 3 years, became the dominant Plasmodium infection in the highest transmission areas in the 1997 rainy season. The vector Anopheles darlingi has also increased during this epidemic in Loreto. Moreover, chloroquine and pyrimethamine-sulfadoxine drug-resistant P. falciparum strains have emerged, which require development of efficacious focal drug treatment schemes.

The South America low-level jet (SALLJ) on the eastern slopes of the Andes is a unique climatological feature in the continent. The SALLJ transports large amounts of moisture and controls the spatiotemporal variability of precipitation in southeast South America. This study shows a remarkable influence of the Atlantic Multidecadal Oscillation (AMO) on decadal-to-multidecadal variability of the SALLJ. The results show a consistent pattern in which active SALLJ days during negative AMO phases are associated with negative precipitation anomalies over northern Amazon and the Atlantic Intertropical Convergence Zone (ITCZ). Increased cross-equatorial flow over northwestern South America combined with the outflow associated with the atmospheric subsidence over the negative precipitation anomalies enhances northerly winds along the eastern slopes of the Andes and Amazon. This atmospheric circulation response, which is more prevalent in the austral winter, intensifies the SALLJ. In the exit region of the SALLJ over southern Brazil, Uruguay and northern Argentina, an anomalous low-level cyclonic circulation is associated with enhanced precipitation. The influence of the AMO on the SALLJ is consistent with paleo-proxy studies showing multidecadal changes in precipitation over the La Plata River drainage basin. The analysis shows that secular trends reinforce the SALLJ and precipitation patterns. Moreover, the study highlights the importance of natural variability (i.e., decadal-multidecadal variations) occurring within long-term trends in the mean state, possibly associated with global warming, and significant changes in the SALLJ and precipitation over South America.