Bubble-mediated transport of benthic microorganisms into the water column: Identification of methanotrophs and implication of seepage intensity on transport efficiency

Abstract

Benthic microorganisms transported into the water column potentially influence biogeochemical cycles and the pelagic food web structure. in the present study six gas-releasing vent sites in the Coal Oil Point seep field (California) were investigated, and the dislocation of microorganisms from the sediment into the water column via gas bubbles released from the seabed was documented. it was found that the methanotrophs transport efficiency was dependent on the volumetric gas flow, with the highest transport rate of 22.7 × 10 3 cells mL gas −1 at a volumetric gas flow of 0.07 mL gas s −1 , and the lowest rate of 0.2 × 10 3 cells mL gas −1 at a gas flow of 2.2 mL gas s −1 . A simple budget approach showed that this bubble-mediated transport has the potential to maintain a relevant part of the watercolumn methanotrophs in the seep field. The bubble-mediated link between the benthic and pelagic environment was further supported by genetic analyses, indicating a transportation of methanotrophs of the family Methylomonaceae and oil degrading bacteria of the genus Cycloclasticus from the sediment into the water column. These findings demonstrate that the bubble-mediated transport of microorganisms influences the pelagic microbial abundance and community composition at gasreleasing seep sites.

Long-term atmospheric emissions for the Coal Oil Point natural marine hydrocarbon seep field, offshore California

“…Additionally, the offshore survey identified focused plumes from beyond the extent of the seep field's 2005 sonar map, specifically in the Goleta Bay, which has been noted (Jordan et al, 2020), and offshore Haskell and Sands beaches, an area with abandoned oil wells, and off Naples Point (Fig. 2a, red arrow).…”

Pelagic Methane Sink Enhanced by Benthic Methanotrophs Ejected From a Gas Seep

“…Patches of elevated MOB cell concentrations were detected in the surface waters at station O3 and O5 of the OUT transect (Figure 2c), presumably indicating a bubble-mediated (Jordan et al, 2020;Schmale et al, 2015) cross-thermocline transport of these cells. Particles (including bacteria) attached to bubble surfaces can thus be transported across strong density gradients, such as thermoclines, that inhibit an exchange of particles or dissolved substances by pure diffusion or advection (Nauw, Linke, et al, 2015;Schmale et al, 2016).…”

“…A comparison of the bubble-mediated MOB cell transport in the Coal Oil Point seep field at the Isla Vista super seep (1.2 × 10 11 MOB cells m −2 d −1 , 700 vents m −2 ; Jordan et al, 2020) with results of our study (1.35 ± 0.6 × 10 15 MOB cells m −2 d −1 , based on a seepage area within the crater of ∼275.5 m 2 ; Leifer, 2015), suggests that MOB cell transport per square meter of active seepage area was four orders of magnitude higher at the Blowout. Based on this comparison, we propose that the resuspension of crater sediment (Schneider von Deimling et al, 2015) played an essential role for the coupling of benthic and pelagic MOB communities at the Blowout, in addition to the bubble-mediated transport of MOB cells, which was the dominant transport process identified in the Coal Oil Point seep field (Jordan et al, 2020). This conclusion is further supported by phylogenetic analysis indicating similarities in the microbial community composition between Blowout crater surface sediments and bottom water (Steinle et al, 2016), as well as an elevated turbidity in the crater interior (Movies S2 and S3, Figure S8 in Supporting Information S1).…”

Long-Term Atmospheric Emissions for the Coal Oil Point Natural Marine Hydrocarbon Seep Field, Offshore California

“…An Additionally, the offshore survey identified focused plumes from beyond the extent of the seep field's 2005-sonar map. Specifically in the Goleta Bay, which has been noted (Jordan et al, 2020), and offshore Haskell and Sands Beaches, areas of abandoned oil wells.…”