Cyanobacteria enhance methylmercury production: A hypothesis tested in the periphyton of two lakes in the Pantanal floodplain, Brazil

Lázaro, Wilkinson Lopes; Guimarães, Jean Rémy Davée; Ignácio, Áurea Regina Alves; Silva, Carolina Joana da; Dı́ez, Sergi

doi:10.1016/j.scitotenv.2013.03.022

Cited by 50 publications

(21 citation statements)

References 34 publications

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“…Additionally, the percentage of Bacteroidetes, Actinobacteria, Verrucomicrobia, and Cyanobacteria decreased upon cultivation in Hg ( Figure 3II). These results contrast with those findings suggesting that Cyanobacteria and Bacteroidetes were tolerant to Hg [20,42,43] and demonstrate that the species of Cyanobacteria and Bacteroidetes present in the studied biofilms were not tolerant to Hg. cultivated in 11 pM, 121 pM, and 1454 pM Hg, respectively.…”

Section: Bacterial Biofilm Compositioncontrasting

confidence: 99%

Long-Term Effects of Mercury on Biofilms Grown in Contaminated Microcosms: A Pilot Study

2019

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Biofilms are important components of the mercury (Hg) biogeochemical cycle. However, Hg effects on biofilm communities are overlooked. Here, we present results of a pilot study on the chronic effects of Hg on biofilms, notably on the potential change of their taxonomic composition. Biofilms were cultivated in microcosms enriched with three different Hg concentrations (11 ± 2 pM, 121 ± 9 pM and 1454 ± 54 pM) for 55 days and examined for their accumulated Hg concentrations and composition. Bioaccumulated Hg concentrations were representative of those encountered in natural environments. Despite the lack of influence on the ash free dry weight and chlorophyll content, the surface coverage of the substrata of biofilms grown in Hg decreased. Algal community were strongly affected by Hg, with a decrease in their richness with Ochrophyta found as the most sensitive phyla. The diversity and richness of bacterial communities did not change upon cultivation in Hg but the presence of Proteobacteria increased with Hg, whereas Bacteroidetes, Actinobacteria, Verrumicrobia, and Cyanobacteria were negatively impacted. Overall, the above findings suggest that the examination of the algal community composition might be used as a potential biomonitoring tool to assess the impacts of environmental Hg concentrations on aquatic systems, which would merit further investigation.

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Section: Bacterial Biofilm Compositioncontrasting

confidence: 99%

Long-Term Effects of Mercury on Biofilms Grown in Contaminated Microcosms: A Pilot Study

2019

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“…In a recent study, Hamelin et al (2015) showed that the rate of net methylation in the biofilms on macroalgae was two orders of magnitude higher than that of the nearby sediment of a temperate wetland. Similarly, Lázaro et al (2013) showed that methylation within biofilms of floating plants in the Amazon were sites of substantial Hg methylation. They also found that the methylation rate correlated with the algal biomass on which these biofilms grow.…”

Section: Resultsmentioning

confidence: 98%

An examination of the factors influencing mercury and methylmercury particulate distributions, methylation and demethylation rates in laboratory-generated marine snow

2015

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In the marine environment, settling particulates have been widely studied for their role as effective vertical transporters of nutrients and metals scavenged from the euphotic zone to the benthos. These particulates are composed of transparent exopolymers, plankton and bacterial cells, detritus and organic matter, and form various size fractions from colloids (<0.2μm) to aggregates, and finally marine snow (>300 μm). As marine snow forms in the water column, anoxic layers form around and within the aggregation potentially creating a prime environment for the methylation of mercury (Hg), which occurs primarily in low oxygen environments. To examine this process, marine aggregates were produced from sieved estuarine seawater (100 μm) in 1-L glass bottles spiked with stable isotope enriched methylmercury (CH3199Hg) and inorganic mercury (200Hg(II)) at 18° C using a roller-table. After the rolling period, different particle-size fractions were collected and analyzed, including: visible marine snow (>300μm), particulates 8 to 300 μm, and particulates 0.2 to 8μm. Particulate analysis indicated higher incorporation of both forms of Hg into marine snow compared to unrolled treatments, with greater incorporation of 200Hg(II) than CH3199Hg. In addition, inorganic Hg was methylated and CH3Hg was demethylated in the larger particulate fractions (>8μm). Methylation and demethylation rates were assessed based on changes in isotopic composition of Hg(II) and CH3Hg, and found to be comparable to methylation rates found in sediments. These results indicate that net Hg methylation can occur in marine snow and smaller aggregates in oxic coastal waters, and that this net formation of CH3Hg may be an important source of CH3Hg in both coastal and open ocean surface environments.

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“…Previous studies demonstrate that MeHg production increases during the flooding phase of the flood pulse in tropical areas, due to greater decomposition of land organic matter incorporated into the body of water, by the creation of lower dissolved oxygen in water habitats, and by the higher density of periphyton associated with the roots of aquatic macrophytes in water ecosystems during this period. Higher periphyton density is linked to higher rates of primary methylation (Guimarães et al, 2006;Ulrich et al, 2001;Lázaro et al, 2013).…”

Section: Spatial and Seasonal Differences In Hg Concentrationsmentioning

confidence: 99%

“…The problem of environment contamination of mercury (Hg) has been an issue in Brazil, especially in the Amazon and Pantanal, which are two of the world's largest floodable areas (Akagi et al, 1995;Malm et al, 1995;Hylander et al, 2000;Guimarães et al, 2000;Del Lama et al, 2011;Lázaro et al, 2013). Informal gold prospecting in the Amazon region has released nearly 2500 tons of Hg directly into water systems and the atmosphere, in different Hg forms from the burning of the gold amalgam (Malm, 1998).…”

Section: Introductionmentioning

confidence: 99%

Non-lethal sampling for mercury evaluation in crocodilians

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Cyanobacteria enhance methylmercury production: A hypothesis tested in the periphyton of two lakes in the Pantanal floodplain, Brazil

Cited by 50 publications

References 34 publications

Long-Term Effects of Mercury on Biofilms Grown in Contaminated Microcosms: A Pilot Study

Long-Term Effects of Mercury on Biofilms Grown in Contaminated Microcosms: A Pilot Study

An examination of the factors influencing mercury and methylmercury particulate distributions, methylation and demethylation rates in laboratory-generated marine snow

Non-lethal sampling for mercury evaluation in crocodilians

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