Avian blood and feathers as biological tools to track impacts from trace-metals: Bioaccumulation data from the biggest environmental disaster in Brazilian history

Evaluation of microplastics and metal accumulation in domestic ducks (Anas platyrhynchos f. domesticus) of a contaminated reservoir in Central Mexico

We procured a total of 22 Anas platyrhynchos f. domesticus (domestic ducks) individuals around the Valsequillo Dam, Puebla, Mexico, to assess ingested plastics and accumulated metals (As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Zn). The morphometric results of all the samples presented adverse body conditions, where the females had less average body weight (1.94 ± 0.30 kg), height (53. 7 ± 2.78 cm) and wingspan length (92.6 ± 7.45 cm) compared to the male species. The coefficients of variation of all the studied elements (CV > 36 %), except Cu in feathers, demonstrated a high degree of variation, implying exogenous contamination from human activities. Nearly all the studied species presented MP ingestion, with an average of 154.9 suspected particles/ individual. The colour of the MPs was mainly blue (35 %) and transparent (32 %), while the principal forms of MPs were fragments (53 %) and filaments (36 %). The SEM-EDX characterization presented carbon and oxygen peaks and affirmed that the extracted particles are polyethylene and polypropylene. The Pollution Load Index values for MPs were found to be >1, signifying that the site is polluted by MPs, and the calculated Potential Risk Index denoted that the ducks are at low risk of exposure to Cd, Cr, Zn and Ni, and a constant exposure to Cu can be harmful. The study will contribute to establishing baseline data to elucidate the degree of accumulation of MPs and metals in domestic ducks which will be used to employ monitoring programs for the sustainable conservation of the aquatic ecosystem.

Methylmercury exposure and risk of wintering migratory birds in the Poyang Lake basin, China

Mercury (Hg), especially methylmercury (MeHg), is a pervasive contaminant that poses significant risks to birds occupying high trophic levels. However, we have little knowledge about the mercury exposure and its risks for birds in Poyang Lake basin, China. Therefore, during 2020-2021, we investigated MeHg concentrations in breast feathers of wintering migratory birds (n = 430 from 43 species belonging to 9 orders) in Poyang Lake Nanji Wetland and Jiangxi Nanfengmian National Nature Reserve, China. MeHg concentrations in breast feathers varied greatly by species, foraging guilds and taxonomic orders, among which the highest concentration was detected in great egret (8849 ± 5975 ng g-1 dw). Comparing with studies worldwide, high MeHg concentrations in feathers of Ardeidae from Pelecaniformes were found in this area. Moreover, herons migrating between northern and southern China had lower MeHg concentration than residents in southern China related to habitat Hg. Considering the applicability and sensitivity of the equations for the transformation of MeHg concentrations in feathers to blood-equivalent total Hg (THg) values, method CJ that the equation based on songbirds was used for the transformation of the songbirds and the equation based on seabirds for the others performed better than other three for risk assessment of bird Hg in this study. 23.1% of birds from Poyang Lake were at risk of Hg exposure based on the method CJ. Carnivorous birds from Pelecaniformes had the highest risk levels, with 37.2% categorized as no risk (≤200 ng g-1 ww), 48.9% as low risk (200-1000 ng g-1 ww), 11.1% as moderate risk (1000-3000 ng g-1 ww), 1.1% as high risk (3000-4000 ng g-1 ww), and 1.7% as severe risk (>4000 ng g-1 ww). These risks suggest long-term monitoring and further advanced studies about freshwater waterbirds Hg exposure is necessary.

Two centuries of ornithological exploration of the Rio Doce Basin, southeastern Brazil. Part II-A catalogue of its birds and a gazetteer

The Rio Doce Hydrographic Basin (RDB) lies almost completely in the Brazilian Atlantic Forest, a highly threatened tropical rainforest. The RDB has suffered dramatic anthropogenic impacts during the last two centuries and is currently one of the most degraded regions in southeastern Brazil. In this paper, we gathered 140,742 bird records collected since the early 19th by more than two thousand naturalists, professional scientists, and citizen scientists. This vast database was compiled from several sources, including published literature, unpublished technical reports, natural history museums, and citizen science platforms. After checking and standardizing the database, we found high species richness in the RDB, with 689 species recorded to date, from which 675 (98%) were documented by specimens or digital vouchers. This database is presented as a detailed catalogue, including maps containing all localities in which each species has been recorded. We present text accounts for 40 noteworthy species recorded in the RDB, and a complete gazetteer for the 636 localities sampled. Preliminary analyses reveal that the RDB avifauna suffered a dramatic change in its species composition during the last two centuries, mostly due to human activity. Highly sensitive species associated to pristine forests vanished, while species associated to dry and open habitat expanded their ranges in the RDB. Finally, in addition to thoroughly characterization of the RDB avifauna, this paper provides the basis for a series of studies about the avifauna of one of the hottest hotspots of biodiversity in the entire Neotropical region.

Organic contamination and multi-biomarker assessment in watersheds of the southern Brazil: an integrated approach using fish from the Astyanax genus

We aimed to examine the responses of pollution biomarkers in feral fish from Astyanax genus collected at three hydrographic regions in southern Brazil and the capacity of these tools to differentiate between various levels of contamination. To achieve this, levels of organochlorine pesticides (liver), as well as the biomarkers AChE (muscle and brain), TBARS (liver), and EROD (liver) were assessed. Collections were conducted in four municipalities (Alegrete, Caraá, Lavras, and Santa Vitória) during 1 year, encompassing winter and summer. Fish from Alegrete were the most contaminated overall, but animals sampled in Caraá, and Lavras also displayed elevated levels of current-use pesticides. Elevated levels of endosulfans, DDTs, HCHs, and current-use pesticides were accompanied by elevated levels of TBARS in the liver. Conversely, fish from Santa Vitória exhibited the highest levels of PAHs, accompanied by elevated levels of EROD in the liver and reduced levels of AChE in muscle and brain. TBARS proved to be a reliable biomarker for assessing impacts arising from pesticide accumulation, while EROD and AChE served as valuable indicators of impacts resulting from PAHs accumulation. Ultimately, the results obtained in this study demonstrate the reliable use of the proposed biomarkers for tracking biological impacts stemming from aquatic pollution using feral Astyanax as biomonitoring species.

Temporal changes in metal and arsenic concentrations in blood and feathers of tropical seabirds after one of the largest environmental disasters associated with mining

Monitoring of contaminant levels in wildlife over time is a tool for assessing the presence and persistence of environmental impacts at ecosystem, community and population levels. Tropical seabirds breeding in the Abrolhos Archipelago, 70 km off the Brazilian coast, forage in areas under the influence of the Doce River discharge. In 2015, the Fundão Dam collapsed and released ca 60 million tons of iron ore tailings into the ocean. In the present study, red-billed tropicbirds Phaethon aethereus and brown boobies Sula leucogaster breeding in Abrolhos were monitored over four years (2019-2022) for metal (Fe, Mn, Zn, Cu, Cr, Hg, Pb, Cd) and metalloid (As) concentrations in blood and feathers. Over six sampling events, metal (loid) concentrations showed strong temporal variation in both tissues. Overall, feathers showed greater element concentrations than blood, with stronger correlations between elements, especially Mn and the nonessential As, Cd, Hg and Pb. Mn is one of the major chemical markers of the Fundão Dam tailings. Metal (loid) concentrations in the tropical seabirds evaluated were above suggested threshold levels for most nonessential elements (As, Cd and Pb), especially in February 2021, when metal (loid) concentrations peaked in feathers. In this case, values were orders of magnitude higher than those observed in other sampling events. This occurred one year after a major rainy season in the Doce River basin, which increased river discharge of contaminated mud into the ocean, where contaminants are further remobilized by winds and currents, resulting in transference through the marine food web. This finding is consistent to what has been observed for other ecosystem compartments monitored in the region under the influence of the Doce River. Our findings highlight the utility of using tropical seabirds as sentinels of marine pollution, revealing strong temporal patterns in metal (loid) concentrations associated to bottom-up climatic processes.

Doce river mining tailings can be an influencing factor in loggerhead turtles reproductive success in Brazil

In November 2015, a tailings dam ruptured and affected the second largest nesting site of loggerhead sea turtles in Brazil. This study aimed to evaluate the reproductive success, and trace elements in female's plasma, freshly laid eggs, unhatched eggs, and dead hatchlings of loggerhead turtles that nest in the coastal area exposed to the mining waste (Povoação, Espírito Santo state) and compare them with animals from an area that was not affected by the tailings (Praia do Forte, Bahia state). Plasma concentrations of As, Cd, Cr, Fe, and Zn were significantly higher in samples from Povoação in comparison to turtles from Praia do Forte. In Povoação, unhatched eggs and dead hatchlings had higher As, Cu, Hg, Mn, and Zn concentrations than freshly laid eggs, and trace elements correlated with the hatching and emergence success. Our findings suggest that the higher concentrations of some metals may influence the incubation period and reproductive success of loggerheads in the affected area.

Trace element bioaccumulation in the hepatic tissue of juvenile green turtles (Chelonia mydas) stranded along the Campos and Espírito Santo basins, southeastern Brazil

This study analyzed the concentrations of 15 (Al, As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, V, Zn) toxicologically important trace elements in the livers of 110 green turtles stranded in two areas of the Brazilian coast. These areas are essential for the refuge, feeding, and reproduction of the species, and the information obtained is intended to support the development of conservation strategies. Higher concentrations were observed in the Região dos Lagos, RJ in almost all elements, except for Al, Mo, Pb, and V. This location showed statistically higher differences in the concentrations of Cd (4.66 ± 2.33 μg.g-1), Fe (846.62 ± 583.06 μg.g-1), and Zn (27.17 ± 10.90 μg.g-1). The differences in trace element concentration patterns between the two study areas are likely influenced by multiple factors, including the bioavailability of trace elements, oceanic upwelling events, anthropogenic activities, habitat characteristics, and organism-specific metabolic processes.