@article {5998, title = {In vitro simulation of oscillatory redox conditions in intertidal sediments: N, Mn, Fe, and P coupling}, journal = {Continental Shelf Research}, year = {2019}, author = {Pierre Anschutz and Bouchet, Sylvain and Gwena{\"e}l Abril and Bridou, Romain and Tessier, Emmanuel and Amouroux, David} } @article {5754, title = {Algal Bloom Exacerbates Hydrogen Sulfide and Methylmercury Contamination in the Emblematic High-Altitude Lake Titicaca}, journal = {Geosciences}, volume = {8}, year = {2018}, abstract = {

Algal blooms occurrence is increasing around the globe. However, algal blooms are uncommon in dominantly oligotrophic high-altitude lakes. Lake Titicaca, the largest freshwater lake in South America, located at 3809 m above the sea level, experienced its first recorded algal bloom covering a large fraction of its southern shallow basin in March{\textendash}April 2015. The dominant algae involved in the bloom was Carteria sp. Water geochemistry changed during the bloom with a simultaneous alkalinization in heterotrophic parts of the lake and acidification in eutrophic shallow areas. A decrease in oxygen saturation (from 105 to 51\%), and a dramatic increase in hydrogen sulfide (H2S) concentrations (from \<0.02 to up to 155 {\textmu}g.L-1) resulted in the massive death of pelagic organisms. Such changes were brought by the exacerbated activity of sulfate-reducing bacteria (SRB) in this sulfate-rich lake. Although levels in total mercury remained stable during the event, MMHg \% rose, highlighting higher conservation of produced MMHg in the water. Such an increase on MMHg \% has the potential to produce exponential changes on MMHg concentrations at the end food web due to the biomagnification process. Our physicochemical and climatological data suggest that unusually intense rain events released large amounts of nutrients from the watershed and triggered the bloom. The observed bloom offers a hint for possible scenarios for the lake if pollution and climate change continue to follow the same trend. Such a scenario may have significant impacts on the most valuable fish source in the Andean region and the largest freshwater Lake in South America. Furthermore, the event illustrates a possible fate of high altitude environments subjected to eutrophication.

}, issn = {2076-3263}, doi = {10.3390/geosciences8120438}, url = {http://www.mdpi.com/2076-3263/8/12/438}, author = {Dar{\'\i}o Ach{\'a} and Gu{\'e}dron, Stephane and Amouroux, David and Point, David and Lazzaro, Xavier and Fernandez, Pablo Edgar and Sarret, G{\'e}raldine} } @article {4627, title = {Association of a Specific Algal Group with Methylmercury Accumulation in Periphyton of a Tropical High-Altitude Andean Lake}, journal = {Archives of Environmental Contamination and Toxicology}, year = {2016}, pages = {1{\textendash}10}, abstract = {

Periphyton relevance for methylmercury (MeHg) production and accumulation are now well known in aquatic ecosystems. Sulfate-reducing bacteria and other microbial groups were identified as the main MeHg producers, but the effect of periphyton algae on the accumulation and transfer of MeHg to the food web remains little studied. Here we investigated the role of specific groups of algae on MeHg accumulation in the periphyton of Schoenoplectus californicus ssp. (Totora) and Myriophyllum sp. in Uru Uru, a tropical high-altitude Bolivian lake with substantial fishing and mining activities accruing around it. MeHg concentrations were most strongly related to the cell abundance of the Chlorophyte genus Oedogonium (r 2\ =\ 0.783, p\ =\ 0.0126) and to no other specific genus despite the presence of other 34 genera identified. MeHg was also related to total chlorophyll-a (total algae) (r 2\ =\ 0.675, p\ =\ 0.0459), but relations were more significant with chlorophyte cell numbers, chlorophyll-b (chlorophytes), and chlorophyll-c (diatoms and dinoflagellates) (r 2\ =\ 0.72, p\ =\ 0.028, r 2\ =\ 0.744, p\ =\ 0.0214, and r 2\ =\ 0.766, p\ =\ 0.0161 respectively). However, Oedogonium explains most variability of chlorophytes and chlorophyll-c (r 2\ =\ 0.856, p\ =\ \<\ 0.001 and r 2\ =\ 0.619, p\ =\ 0.002, respectively), suggesting it is the most influential group for MeHg accumulation and periphyton algae composition at this particular location and given time.

}, issn = {1432-0703}, doi = {10.1007/s00244-016-0324-2}, url = {http://dx.doi.org/10.1007/s00244-016-0324-2}, author = {Lanza, William G. and Dar{\'\i}o Ach{\'a} and Point, David and Masbou, Jeremy and Alanoca, Lucia and Amouroux, David and Lazzaro, Xavier} }