Metagenome sequencing of the microbial community of a solar saltern crystallizer pond at cáhuil lagoon, chile.

Cáhuil Lagoon in central Chile harbors distinct microbial communities in various solar salterns that are arranged as interconnected ponds with increasing salt concentrations. Here, we report the metagenome of the 3.0- to 0.2-µm fraction of the microbial community present in a crystallizer pond with 34% salinity

Respuesta de la comunidad microbiana al enriquecimiento de amonio excretado por salmones en ecosistemas de fiordos

Tesis (Doctor en Medicina de la Conservación)Fish farming in floating cages, like salmon farming in fjords, contribute to the ammonium (NH4+) enrichment due to salmon excretion, feces and non-eaten food. This "extra" NH4+ can be assimilated by phytoplankton and microorganisms, and be aerobically oxidized through nitrification to nitrate (N03-) by bacteria and archaea. The response of ammonia-oxidizers (archaea and bacteria, AOA and AOB), nitriteoxidizers (Nitrospina sp) and bacterial community structure to NH4+ enrichment were studied in situ and experimentally using molecular (cloning, qPCR, T-RFLP and 454 pyrosequencing) and chemical approaches. In situ: Brackish and marine water were collected from a salmon farming transect at Comau fjord during contrasting salmon production periods: rest (winter 2012), growth and harvest (summer and winter 2013). Nitrifier community was characterized by C. Nitrosopumilus maritimus (AOA) and Nitrosomonas sp. (AOB), where maximum abundances of C. Nitrosopumilus maritimus (AOA), Nitrospina sp. and Nitrospina sp. transcripts occurred in the brackish layer, while during productive periods C. Nitrosopumilus maritimus abundances were co-varied with NH4+ concentrations inside salmon cages (summer) and adjacent areas (winter). cDNA:DNA ratios indicated higher growth during winter 2013 associated with NH4+ enrichment derived from salmon production accumulated in the brackish layer inside salmon cages and in the vicinity (up to 700 m from the cages at summer and >1 000 winter, whereas during rest period the highest NH4+ concentration was at Vodudahue river. Experiments: Mesocosms simulating different salmon farming NH4+ enrichment contributions (from 0.3 to 4.7 umol NH4+ L-1 o-1) were carried out at contrasting fjords ecosystems, Comau Fjord (Chile) and Hopavagen (Norway), at summer and late summer 2011, respectively. Large variations were found in Chilean richness (60±28 genus) and diversity (7.93±0.47 H, 'Shannon) between treatments and incubation days, while Norwegian experiments only showed small variations between them (54.2±8.0 and 2.2±0.2, Richness and H, 'Shannon, respectively). Our results suggest that in Camau Fjord, NH4+ enrichment events occur from salmon production and also naturally fram river inputs, supporting an abundant and active nitrifying community potentially processing only part of the extra NH4+ that occurs, predominantly outside the salmon cages. On the other hand, mesocosms results indicate that Chilean bacterial community structure are sensitive ta NH4+ enrichment and incubation days, causing a decrease in richness, diversity and community composition dominating Alphaprateabacteria over Cyanabacteria and Flavabacteria. Alphaprateabacteria species change drastically, from Rhadabacteraceae and Rhadabacter to sulfite oxidation bacteria, while Norwegian mesocosms were dominated by the same Alphaprateabacteria species without changing species abundance and composition even at high addition treatments and maximum incubation days. These results highlight Chileans microbial community as sensitive ta NH4+ enrichment which represent an environmental concern, which could be related with production problems, leading ta economic and indirectly public health issues

Metagenome sequencing of the microbial community of a solar saltern crystallizer pond at cáhuil lagoon, chile.

Cáhuil Lagoon in central Chile harbors distinct microbial communities in various solar salterns that are arranged as interconnected ponds with increasing salt concentrations. Here, we report the metagenome of the 3.0- to 0.2-µm fraction of the microbial community present in a crystallizer pond with 34% salinity