To test the hypothesis that different drivers shape the diversity and biogeography of the total and active bacterial community, we examined the bacterial community composition along two transects, one from the inner Pearl River estuary to the open waters of the South China Sea (SCS) and the other from the Luzon Strait to the SCS basin, using 454 pyrosequencing of the 16S rRNA and 16S rRNA gene (V1-3 regions) and thereby characterizing the active and total bacterial community, respectively. The diversity and biogeographic patterns differed substantially between the active and total bacterial communities. Although the composition of both the total and active bacterial community was strongly correlated with environmental factors and weakly correlated with geographic distance, the active bacterial community displayed higher environmental sensitivity than the total community and particularly a greater distance effect largely caused by the active assemblage from deep waters. The 16S rRNA vs. rDNA relationships indicated that the active bacteria were low in relative abundance in the SCS. This might be due to a high competition between active bacterial taxa as indicated by our community network models. Based on these analyses, we speculate that high competition could cause some dispersal limitation of the active bacterial community resulting in a distinct distance-decay relationship. Altogether, our results indicated that the biogeographic distribution of bacteria in the SCS is the result of both environmental control and distance decay.
In this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO(2)DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and Reusable). GO(2)DAT will combine data from the coastal and open ocean, as measured by the chemical Winkler titration method or by sensors (e.g., optodes, electrodes) from Eulerian and Lagrangian platforms (e.g., ships, moorings, profiling floats, gliders, ships of opportunities, marine mammals, cabled observatories). GO(2)DAT will further adopt a community-agreed, fully documented metadata format and a consistent quality control (QC) procedure and quality flagging (QF) system. GO(2)DAT will serve to support the development of advanced data analysis and biogeochemical models for improving our mapping, understanding and forecasting capabilities for ocean O-2 changes and deoxygenation trends. It will offer the opportunity to develop quality-controlled data synthesis products with unprecedented spatial (vertical and horizontal) and temporal (sub-seasonal to multi-decadal) resolution. These products will support model assessment, improvement and evaluation as well as the development of climate and ocean health indicators. They will further support the decision-making processes associated with the emerging blue economy, the conservation of marine resources and their associated ecosystem services and the development of management tools required by a diverse community of users (e.g., environmental agencies, aquaculture, and fishing sectors). A better knowledge base of the spatial and temporal variations of marine O-2 will improve our understanding of the ocean O-2 budget, and allow better quantification of the Earth's carbon and heat budgets. With the ever-increasing need to protect and sustainably manage ocean services, GO(2)DAT will allow scientists to fully harness the increasing volumes of O-2 data already delivered by the expanding global ocean observing system and enable smooth incorporation of much higher quantities of data from autonomous platforms in the open ocean and coastal areas into comprehensive data products in the years to come. This paper aims at engaging the community (e.g., scientists, data managers, policy makers, service users) toward the development of GO(2)DAT within the framework of the UN Global Ocean Oxygen Decade (GOOD) program recently endorsed by IOC-UNESCO. A roadmap toward GO(2)DAT is proposed highlighting the efforts needed (e.g., in terms of human resources). ; All authors would like to thank IOC-UNESCO, International Ocean Carbon Coordination Project (IOCCP), NOAA, and the German SFB754. MG is funded by the Fonds National de la Recherche Scientifique (FRS-FNRS) and received fundings from the FNRS BENTHOX program grant T.1009.15, the Copernicus Marine Service (CMEMS), and the European Union's Horizon 2020 BRIDGE-BS project under grant agreement No. 101000240. MG, VG, KI, and BDew are supported by the Project CE2COAST funded by ANR (FR), BELSPO (BE), FCT (PT), IZM (LV), MI (IE), MIUR (IT), Rannis (IS), and RCN (NO) through the 2019 "Joint Transnational Call on Next Generation Climate Science in Europe for Oceans" initiated by JPI Climate and JPI Oceans. MT, KC, and VG acknowledge support from the United States National Science Foundation grant OCE-1840868 to the Scientific Committee on Oceanic Research (SCOR, United States). BoD also acknowledges support from ANID grants R20F0008-CEAZA and 1190276. This research (through VG, AP and BoD) received fundings from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 869300 (FutureMARES). CB, AP, VG, LC, BrD, VR, VT, and CS acknowledge support of the French CES ODATIS Oxygen through INSU funding. SKL acknowledges support from the Research Council of Norway (Grant No. 269753). This manuscript is a contribution to the UN Decade Global Ocean Oxygen (GOOD) Program.
