Toxic metals and associated sporulated bacteria on Andean hummingbird feathers

Abstract

Human activities in the Sabana de Bogotá, Colombia, release toxic metals such as lead (Pb) and chromium (Cr) into the environment polluting the air, water, and soil. Because birds are in contact with these pollutants and their sources, they may serve as bioindicator organisms. We evaluated the use of hummingbird feathers obtained from individuals captured in three sites of the Sabana de Bogotá as bioindicators of toxic metal pollution using spectrophotometric and spectroscopic methods based on single-feather samples. We also characterized the bacterial microbiota associated with hummingbird feathers by molecular identification using the 16S rRNA with a special focus on sporulated bacteria. Finally, we described the interactions which naturally occur among the feathers, their associated bacteria, and pollutants. We found differences in Pb and Cr concentrations between sampling sites, which ranged from 2.11 to 4.69 ppm and 0.38 to 3.00 ppm, respectively. This may reflect the impact of the activities held in those sites which release pollutants to the environment. Bacterial assemblages mainly consisted of sporulated bacilli in the Bacillaceae family (65.7 % of the identified morphotypes). We conclude that the feathers of wild tropical birds, including hummingbirds, can be used as lead and chromium bioindicators and that bacteria growing on feathers may in fact interact with these two toxic metals.

Considering pollinators' ecosystem services in the remediation and restoration of contaminated lands: Overview of research and its gaps

“…Hummingbirds should, therefore, be considered separately from other songbirds with respect to contaminant exposure. Their small size makes nonlethal sampling difficult, but insecticides, including neonicotinoids, have been detected in feathers and carcasses (Graves et al, 2019), and metals have been detected in feathers (Gongora et al, 2016; Mikoni et al, 2017). Feathers, as indicators of contaminant exposure, can be quite variable, however (Peterson et al, 2019), so reports should be interpreted with care.…”

Reported Lead Levels in Different Environmental Matrices in Colombia

“…Other animal species such as hummingbirds of the Bogotá Savanna were used as bioindicators of Pb, obtaining an average concentration of 3.25 ppm in the Encenillo Reserve, in the municipality of Guasca, 4.05 ppm in the Hacienda San Carlos of the municipality of Zipacón, and 4.69 ppm on the campus of the Universidad de los Andes in the city of Bogotá [69]. These values were associated with the environmental contamination of the areas produced by mining activities and nearby roads.…”

Contrast between a mathematical model and the bioreduction process of Cr(VI) by consortia of bacteria isolated from wastewater of the Pasto River

“…Chromium is found in high concentrations in most of the waste generated in industrial activities, such as: galvanizing, alloys, tanning processes, and textile dyeing (7)(8)(9)(10). In relation to this, it has been determined that the effects of chromium for the environment and human health depend on the oxidation state, the most stable are the trivalent and hexavalent forms, although both forms are harmful, the latter is considered the most toxic; due to characteristics such as high solubility in water, high degree of oxidation and ability to cross biological membranes, causing alterations in the cellular structure, including DNA (11,12,9).…”