Decadal Variability in Subsurface Nutrient Availability on the Scotian Shelf Reflects Changes in the Northwest Atlantic Ocean

Lehmann, N.; Reed, D. C.; Buchwald, C.; Lavoie, D.; Yeats, P. A.; Mei, Z.‐P.; Wang, Z.; Johnson, C. L.

doi:10.1029/2023jc019928

Cited by 4 publications

(1 citation statement)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we demonstrate that psB12 quota in 8102 significantly decreased in low N:P, despite no change in growth rate or significant change in demand (MetH abundance) (Fig 2A,C). This result is of potential importance for the Scotian Shelf region, as a decrease in dissolved nitrogen relative to phosphorus has been observed since 2010 and is expected to continue in the future (Lehmann et al, 2023). On average, the N:P ratio in environmental samples was (3.5 ± 4.5 N:P) (Table S2) however no correlation between N:P and psB12 (pM) was observed.…”

Section: Variability In Psb12 Quotas and Protein Inventories In Synec...mentioning

confidence: 81%

Pseudocobalamin production and use in marineSynechococcuscultures and communities

Bannon,

Soto,

Rowland

et al. 2024

Preprint

View full text Add to dashboard Cite

Cobalamin influences marine microbial communities because an exogenous source is required by most eukaryotic phytoplankton, and demand can exceed supply. Pseudocobalamin, psB12, is a cobalamin analog that is produced and used by most cyanobacteria but is not directly available to eukaryotic phytoplankton. A subset of microbes can remodel pseudocobalamin into cobalamin, but a scarcity of pseudocobalamin measurements impedes our ability to evaluate its importance for marine cobalamin production. Here, we perform simultaneous measurements of pseudocobalamin and methionine synthase (MetH), the key protein that uses it as a co-factor, inSynechococcuscultures and natural communities. InSynechococcussp. WH 8102, pseudocobalamin quota decreases in low temperature (17 °C) and low N:P, while MetH did not. Pseudocobalamin and MetH quotas were influenced by culture methods (batch vs semi-continuous) and growth phase (exponential vs stationary). Despite the variability present in cultures, we found a comparably consistent quota of 296 ± 101 pseudocobalamin molecules per cyanobacterial cell in the Northwest Atlantic Ocean, suggesting that cyanobacterial cell counts may be sufficient to estimate pseudocobalamin inventories in this region. This work offers insights into cellular pseudocobalamin metabolism and the environmental and physiological conditions that may influence it and provides environmental measurements to further our understanding of when and how pseudocobalamin can influence marine microbial communities.

show abstract

Section: Variability In Psb12 Quotas and Protein Inventories In Synec...mentioning

confidence: 81%

Pseudocobalamin production and use in marineSynechococcuscultures and communities

Bannon,

Soto,

Rowland

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

Physical Drivers and Biogeochemical Effects of the Projected Decline of the Shelfbreak Jet in the Northwest North Atlantic Ocean

Garcia‐Suarez,

Fennel

2024

J Adv Model Earth Syst

View full text Add to dashboard Cite

A solid understanding of the mechanisms behind the presently observed, rapid warming of the northwest North Atlantic Continental Shelf and their biogeochemical impacts is lacking. We hypothesize that a weakening of the Labrador Current System (LCS), especially the shelfbreak jet along the Scotian Shelf, is contributing to these changes and that the future evolution of the LCS will be key to accurate projections. Here we analyze the response of a transient simulation of the high‐resolution GFDL Climate Model 2.6 (CM2.6) which realistically simulates the regional circulation but includes only a highly simplified representation of ocean biogeochemistry. Then, we use the CM2.6 to force a medium‐complexity regional biogeochemical ocean model, the Atlantic Canada Model, to obtain projections of nutrient availability on the shelf. In the simulation, the shelfbreak jet weakens because of a reduction of the along‐shelf pressure gradient caused by a buoyancy gain of the upper water column along the shelf edge. This buoyancy gain is the result of warmer waters along the continental slope. Importantly, we find that the temperature‐based criterion used commonly to pinpoint the location of the Gulf Stream is misleading, causing an overestimation of the northward migration of the Gulf Stream. A fixed isotherm may indicate northward movement as a result of basin‐wide warming and not necessarily reflect changes in dynamics. The combination of the weakened shelfbreak jet and a lowering of nutrient concentrations in its source water reduce nutrient availability on the northwest North Atlantic shelf by one third by 2100 in the projection analyzed.

show abstract

Production and utilization of pseudocobalamin in marine Synechococcus cultures and communities

Bannon,

Soto,

Rowland

et al. 2024

Environmental Microbiology

View full text Add to dashboard Cite

Cobalamin influences marine microbial communities because an exogenous source is required by most eukaryotic phytoplankton, and demand can exceed supply. Pseudocobalamin is a cobalamin analogue produced and used by most cyanobacteria but is not directly available to eukaryotic phytoplankton. Some microbes can remodel pseudocobalamin into cobalamin, but a scarcity of pseudocobalamin measurements impedes our ability to evaluate its importance for marine cobalamin production. Here, we perform simultaneous measurements of pseudocobalamin and methionine synthase (MetH), the key protein that uses it as a co‐factor, in Synechococcus cultures and communities. In Synechococcus sp. WH8102, pseudocobalamin quota decreases in low temperature (17°C) and low nitrogen to phosphorus ratio, while MetH did not. Pseudocobalamin and MetH quotas were influenced by culture methods and growth phase. Despite the variability present in cultures, we found a comparably consistent quota of 300 ± 100 pseudocobalamin molecules per cyanobacterial cell in the Northwest Atlantic Ocean, suggesting that cyanobacterial cell counts may be sufficient to estimate pseudocobalamin inventories in this region. This work offers insights into cellular pseudocobalamin metabolism, environmental and physiological conditions that may influence it, and provides environmental measurements to further our understanding of when and how pseudocobalamin can influence marine microbial communities.

show abstract

Decadal Variability in Subsurface Nutrient Availability on the Scotian Shelf Reflects Changes in the Northwest Atlantic Ocean

Cited by 4 publications

References 88 publications

Pseudocobalamin production and use in marineSynechococcuscultures and communities

Pseudocobalamin production and use in marineSynechococcuscultures and communities

Physical Drivers and Biogeochemical Effects of the Projected Decline of the Shelfbreak Jet in the Northwest North Atlantic Ocean

Production and utilization of pseudocobalamin in marine Synechococcus cultures and communities

Contact Info

Product

Resources

About