Browsing by Author "Fernandez, Camila"

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    Antibiotics florfenicol and flumequine in the water column and sediments of Puyuhuapi Fjord, Chilean Patagonia
    (PERGAMON-ELSEVIER SCIENCE LTD, 2021) Jara, Bibiana; Tucca, Felipe; Srain, Benjamin M.; Mejanelle, Laurence; Aranda, Mario; Fernandez, Camila; Pantoja Gutierrez, Silvio
    Chile is a major global producer of farmed salmon in the fjords of Patagonia, and therefore a major consumer of antibiotics. We tested whether the antibiotics florfenicol and flumequine persisted in the large Puyuhuapi Fjord after the six months following mandatory concerted treatment by all salmon farms present in the fjord. Antibiotics were detected in 26% of analyzed samples, but only within the particulate phase, with concentrations of florfenicol of up to 23.1 ng L(-)1, where detected. Flumequine was present in one sample at trace concentration, and neither antibiotic was detected in the dissolved phase nor in surface sediments. A fugacity-based model predicted that flumequine should theoretically remain in surface sediments at the sub-Minimal Inhibiting Concentrations (sub-MIC) previously shown to promote selection for antibiotic resistance in bacteria. Our observations suggest that surface sediments might act as a reservoir for antibiotic resistomes of bacteria, and that bacteria bearing antibiotic resistance genes could eventually become a risk for human health through the consumption of marine products. (C) 2021 Published by Elsevier Ltd.
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    Variability of nitrifying communities in surface coastal waters of the Eastern South Pacific (similar to 36 degrees S)
    (WILEY, 2016) Levipan, Hector A.; Molina, Veronica; Anguita, Cristobal; Rain Franco, Angel; Belmar, Lucy; Fernandez, Camila
    We report the seasonal and single-diurnal variability of potentially active members of the prokaryote community in coastal surface waters off central Chile and the relationship between nitrifiers and solar radiation by combining 16S cDNA-based pyrosequencing, RTqPCR of specific gene markers for nitrifiers (amoA, for general AOA, AOA-A, AOA-B, Nitrosopumilus maritimus and beta-AOB; and 16S rRNA gene for Nitrospina- like NOB), and solar irradiance measurements. We also evaluated the effects of artificial UVA-PAR and PAR spectra on nitrifiers by RT-qPCR. All nitrifiers (except AOA-B ecotype) were detected via RTqPCR but AOA was the only group detected by pyrosequencing. Results showed high variability in their transcriptional levels during the day which could be associated to sunlight intensity thresholds in winter although AOA and Nitrospina-like NOB transcript number were also potentially related with environmental substrate availability. Only N. maritimus amoA transcripts showed a significant negative correlation with solar irradiances in both periods. During springsummer, Nitrospina transcripts decreased at higher sunlight intensities, whereas the opposite was found during winter under natural (in situ) and artificial light experiments. In summary, a nitrifying community with variable tolerance to solar radiation is responsible for daily nitrification, and was particularly diverse during winter in the study area.
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    Water column circulation drives microplastic distribution in the Martinez-Baker channels; A large fjord ecosystem in Chilean Patagonia
    (PERGAMON-ELSEVIER SCIENCE LTD, 2020) Castillo, Cristobal; Fernandez, Camila; Gutierrez, Marcelo H.; Aranda, Mario; Urbina, Mauricio A.; Yanez, Jorge; Alvarez, Angela; Pantoja Gutierrez, Silvio
    We investigated the distribution of microplastics in the water column along a large remote estuarine system located between the Northern and Southern Patagonian Ice Fields in Chilean Patagonia, and connected with the Pacific Ocean through the Gulf of Penas. Microplastic particles were found in all samples, with abundances ranging from 0.1 to 7 particles/m(3). Polymers identified were principally acrylics, PET, and cellophane.