Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions

PeerJ

article

Nataly Carolina Guevara Campoverde¹  Christiane Hassenrück²  Pier Luigi Buttigieg³  Astrid Gärdes² 

[1] Galapagos Science Center, Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito;Tropical Marine Microbiology, Department of Biogeochemistry and Geology, Leibniz-Centre for Tropical Marine Reseach;HGF-MPG Group for Deep Sea Ecology and Technology, Alfred-Wegener-Institut

关键词: Galapagos;    Bacterial communities;    Upwelling;    El Niño event;    Organic carbon degradation;    Marine carbon cycle;   

DOI  :  10.7717/peerj.5984

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Bacteria play a crucial role in the marine carbon cycle, contributing to the production and degradation of organic carbon. Here, we investigated organic carbon pools, aggregate formation, and bacterioplankton communities in three contrasting oceanographic settings in the Galapagos Archipelago. We studied a submarine CO2 vent at Roca Redonda (RoR), an upwelling site at Bolivar Channel (BoC) subjected to a weak El Niño event at the time of sampling in October 2014, as well as a site without volcanic or upwelling influence at Cowley Islet (CoI). We recorded physico-chemical parameters, and quantified particulate and dissolved organic carbon, transparent exopolymeric particles, and the potential of the water to form larger marine aggregates. Free-living and particle-attached bacterial communities were assessed via 16S rRNA gene sequencing. Both RoR and BoC exhibited temperatures elevated by 1–1.5 °C compared to CoI. RoR further experienced reduced pH between 6.8 and 7.4. We observed pronounced differences in organic carbon pools at each of the three sites, with highest dissolved organic carbon concentrations at BoC and RoR, and highest particulate organic carbon concentrations and aggregate formation at BoC. Bacterioplankton communities at BoC were dominated by opportunistic copiotrophic taxa, such as Alteromonas and Roseobacter, known to thrive in phytoplankton blooms, as opposed to oligotrophic taxa dominating at CoI, such as members of the SAR11 clade. Therefore, we propose that bacterial communities were mainly influenced by the availability of organic carbon at the investigated sites. Our study provides a comprehensive characterization of organic carbon pools and bacterioplankton communities, highlighting the high heterogeneity of various components of the marine carbon cycle around the Galapagos Archipelago.

【 授权许可】

CC BY