Abstract

This research exchange allowed me to (1) visit a C-DEBI supported collaborator (Beth Orcutt) at the Bigelow Laboratory for Oceans Sciences (BLOS), as well as (2) cover the costs associated with travel and shipment of materials to and from a research cruise to the Juan de Fuca Ridge flank (May 2019, AT42-11). These efforts are important components of my PhD research, which is focused on understanding the role of microbial activity on mineral dissolution through novel techniques including in-situ seafloor experiments and the use of isotopic spikes to quantify rates. The BLOS visit allowed us to perform some preliminary analyses of microbial colonization on mineral substrates in the oceanic sub-surface (samples from North Pond, 2017 cruise AT39-01), as well as prepare for the Juan de Fuca cruise by detailing in-situ and ship-board experimental design. Support for the cruise logistics helped with collecting over 100 liquid and particulate samples from deep-ocean and crustal waters. Preliminary results have shown clear mineral dissolution and precipitation associated with microbial colonization of mineral substrates in crustal fluids. Future steps involve quantifying mineral dissolution kinetics, and contrasting results from in-situ experiments with those performed in the laboratory. This latter part will allow us to constrain specific metabolic mechanisms controlling microbe-mineral interactions and shed light on processes active in crustal fluids. Understanding these will significantly inform us on the metabolic potential driving microbial colonization of mineral surfaces, mineral dissolution kinetics, nutrient bioavailability and the overall controls of crustal fluid geochemistry (C-DEBI themes 2 and 3).

Figure 1: SEM images of bacterial colonization of mineral surfaces, and associated precipitation of secondary mineral phases on North Pond samples, collected during the visit to BLOS supported by this research exchange. These images are available through BCO-DMO (https://www.bco-dmo.org/dataset/756152) and were part of the NSF OCE-1536539 grant.

Figure 2: Group photo on the R/V Atlantis, courtesy of RV Atlantis cruise AT42-11, 2019, chief scientist Beth Orcutt, Bigelow Laboratory for Ocean Sciences, US National Science Foundation, © Woods Hole Oceanographic Institution.