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Oil has been extracted from the Western Amazon since the 1920s, leading to severe environmental contamination due to frequent occurrence oil spills and the dumping of produced water. Local inhabitants, along with environmental and human rights organizations, have reported the adverse effects of oil-related pollution on their livelihoods and the ecosystems they depend on. Here, we study accumulation of oil-related heavy metals in wildlife, and its subsequent incorporation into the trophic chain. We analysed the concentration of 14 heavy metals (Cd, Cr, Hg, As, Ni, V, Ba, Se, Be, Fe, Cu, Zn, Mn, Al) in liver samples from 78 lowland pacas (Cuniculus paca) hunted for subsistence in an oil-polluted area from the northern Peruvian Amazon where oil has been extracted since the 1970s (n = 38), and two control areas, the Yavari-Mirín River basin (n = 20), and the Pucacuro River basin (n = 20). Pacas in the oil-polluted area have significantly higher concentrations of Cd (P < 0.01) and Ba (P < 0.0001) compared to those in control areas, suggesting bioaccumulation of oil-related pollution. Conversely, Se levels were significantly lower in the oil-polluted area (P < 0.0001), likely due to the sequestration of Se by other heavy metals, particularly Cd. Additionally, minor variations in other heavy metals, e.g., Fe and Zn, were observed in pacas from the oil-polluted area, whereas control areas showed higher concentrations of Ni and Cu. Mn and Al levels did not significantly differ between the study areas. These results underscore the impact of oil extraction on the absorption and assimilation of heavy metals in wildlife, point at oil activities as the source of the high and unsafe blood Cd levels reported for the indigenous population of the studied oil extraction area and raise concerns about the long-term health risks from oil extraction posed to local Indigenous People who rely on subsistence hunting.

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BACKGROUND: High blood lead levels (BLLs) have been previously reported in indigenous people living in communities in the northern Peruvian Amazon. Oil extraction activities have been conducted in the area since the 1970s and have been identified as a source of lead exposure. OBJECTIVE: Measure BLL and assess risk factors associated with BLL among indigenous populations from four river basins of the northern Peruvian Amazon. METHODS: Participants from 39 communities were selected using a two-stage stratified random selection strategy and were visited between May and June 2016. Information on risk factors was collected using structured questionnaires and blood samples were taken. Overall, complete information was available from 1047 individuals (309 < 12 years old, 738 ≥ 12 years). BLL was determined using atomic absorption spectrophotometry in a graphite chamber. Weighted linear logistic regression models were used to study the association between socio-demographic variables, self-reported life-style factors, environmental, geographical and occupational exposures and BLLs. RESULTS: Geometric mean (95% CI) BLL was 4.9 (4.5, 5.4) µg/dL in participants <12 years and 5.7 (5.4, 6.0) µg/dL in older participants. There were marked differences in BLL between river basins with the highest levels observed in the Corrientes river basin [8.1 (7.2, 9.1) µg/dL <12 years and 8.8 (8.0, 9.6) µg/dL older participants]. High BLL was associated with older age, being male, living in the Pastaza, Tigre or Corrientes river basins and consumption of fish offal in children and adults. Increased Euclidean distance between residence and oil production facilities was associated with a small reduction in BLL. CONCLUSION: BLLs that pose a health risk were detected in the study population of a non-industrialized and remote area of the Amazon. The highest BLLs were observed in those river basins where relative oil extraction activity and environmental levels of contaminants have been reported to be greatest.

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It has been suggested that traditional ecological knowledge (TEK) may play a key role in forest conservation. However, empirical studies assessing to what extent TEK is associated with forest conservation compared with other variables are rare. Furthermore, to our knowledge, the spatial overlap of TEK and forest conservation has not been evaluated at fine scales. In this paper, we address both issues through a case study with Tsimane' Amerindians in the Bolivian Amazon. We sampled 624 households across 59 villages to estimate TEK and used remote sensing data to assess forest conservation. We ran statistical and spatial analyses to evaluate whether TEK was associated and spatially overlapped with forest conservation at the village level. We find that Tsimane' TEK is significantly and positively associated with forest conservation although acculturation variables bear stronger and negative associations with forest conservation. We also find a very significant spatial overlap between levels of Tsimane' TEK and forest conservation. We discuss the potential reasons underpinning our results, which provide insights that may be useful for informing policies in the realms of development, conservation, and climate. We posit that the protection of indigenous cultural systems is vital and urgent to create more effective policies in such realms.

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Most oil extraction areas in the Peruvian Amazon are within indigenous territories. Poor environmental practices have exposed the indigenous population to metals. We conducted a survey in two indigenous Kukama communities to assess body burdens of metals after the occurrence of two major oil spills in 2014. Urine levels above those recommended by the Peruvian Ministry of Health were observed in 50% and 17% of the study population for mercury and cadmium, respectively.

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Videos recorded with infrared camera traps placed in petroleum contaminated areas of the Peruvian Amazon have shown that four wildlife species, the most important for indigenous peoples' diet (lowland tapir, paca, red-brocket deer and collared peccary), consume oil-contaminated soils and water. Further research is needed to clarify whether Amazonian wildlife's geophagy can be a route of exposure to petrogenic contamination for populations living in the vicinity of oil extraction areas and relying on subsistence hunting.

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Oil extraction activities in the Northern Peruvian Amazon have generated a long-standing socio-environmental conflict between oil companies, governmental authorities and indigenous communities, partly derived from the discharge of produced waters containing high amounts of heavy metals and hydrocarbons. To assess the impact of produced waters discharges we conducted a meta-analysis of 2951 river water and 652 produced water chemical analyses from governmental institutions and oil companies reports, collected in four Amazonian river basins (Marañon, Tigre, Corrientes and Pastaza) and their tributaries. Produced water discharges had much higher concentrations of chloride, barium, cadmium and lead than are typically found in fresh waters, resulting in the widespread contamination of the natural water courses. A significant number of water samples had levels of cadmium, barium, hexavalent chromium and lead that did not meet Peruvian and international water standards. Our study shows that spillage of produced water in Peruvian Amazon rivers placed at risk indigenous population and wildlife during several decades. Furthermore, the impact of such activities in the headwaters of the Amazon extended well beyond the boundaries of oil concessions and national borders, which should be taken into consideration when evaluating large scale anthropogenic impacts in the Amazon.

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Understanding how indigenous peoples' management practices relate to biological diversity requires addressing contemporary changes in indigenous peoples' way of life. This study explores the association between cultural change among a Bolivian Amazonian indigenous group, the Tsimane', and tree diversity in forests surrounding their villages. We interviewed 86 informants in six villages about their level of attachment to traditional Tsimane' values, our proxy for cultural change. We estimated tree diversity (Fisher's Alpha index) by inventorying trees in 48 0.1-ha plots in old-growth forests distributed in the territory of the same villages. We used multivariate models to assess the relation between cultural change and alpha tree diversity. Cultural change was associated with alpha tree diversity and the relation showed an inverted U-shape, thus suggesting that tree alpha diversity peaked in villages undergoing intermediate cultural change. Although the results do not allow for testing the direction of the relation, we propose that cultural change relates to tree diversity through the changes in practices and behaviors that affect the traditional ecological knowledge of Tsimane' communities; further research is needed to determine the causality. Our results also find support in the intermediate disturbance hypothesis, and suggest that indigenous management can be seen as an intermediate form of anthropogenic disturbance affecting forest communities in a subtle, non-destructive way.

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Researchers have argued that indigenous peoples preferably use the most apparent plant species, particularly for medicinal uses. However, the association between the ecological importance of a species and its usefulness remains unclear. In this paper we quantify such association for six use categories (firewood, construction, materials, food, medicines and other uses). We collected data on the uses of 58 tree species, as reported by 93 informants in 22 villages in the Tsimane' territory (Bolivian Amazon). We calculated the ecological importance of the same species by deriving their importance value index (IVI) in 48 0.1-ha old-growth forest plots. Matching both data sets, we found a positive relation between the IVI of a species and its overall use value (UV) as well as with its UV for construction and materials. We found a negative relation between IVI and UV for species that were reportedly used for medicine and food uses, and no clear pattern for the other categories. We hypothesize that species used for construction or crafting purposes because of their physical properties are more easily substitutable than species used for medicinal or edible purposes because of their chemical properties.

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Among the different factors associated to change in traditional ecological knowledge, the study of the relations between cultural change and traditional ecological knowledge has received scan and inadequate scholarly attention. Using data from indigenous peoples of an Amazonian society facing increasing exposure to the mainstream Bolivian society, we analyzed the relation between traditional ecological knowledge, proxied with individual plant use knowledge (n=484), and cultural change, proxied with individual- and village-level (n=47) measures of attachment to traditional beliefs and values. We found that both the individual level of detachment to traditional values and the village level of agreement in detachment to traditional values were associated with individual levels of plant use knowledge, irrespective of other proxy measures for cultural change. Because both the individual- and the village-level variables bear statistically significant associations with plant use knowledge, our results suggest that both the individual- and the supra-individual level processes of cultural change are related to the erosion of plant use knowledge. Results from our work highlight the importance of analyzing processes that happen at intermediary social units -the village in our case study- to explain changes in traditional ecological knowledge.