VITAMIN B12 AND KEY DRIVERS IN AQUATIC ECOSYSTEMS: A COMPREHENSIVE REVIEW OF SEVEN DECADES OF RESEARCH

We reviewed the literature on field measurements of vitamin B12 (cobalamin) and discussed the environmental factors that regulate its availability and distribution. Synthesized by certain bacteria and archaea, vitamin B12 is essential for over 50% of phytoplankton taxa and may influence their growth and community composition. Vitamin B12 encompasses several structurally similar variants, discussed in detail when possible, and we distinguish between the concentrations of dissolved and particulate forms. Overall, vitamin B12 concentrations showed spatial, vertical, and temporal variability. Spatial variability was ecosystem-dependent; for example, freshwater ecosystems generally exhibited higher concentrations of dissolved and particulate B12 than marine ecosystems, possibly due to higher nutrient and cobalt concentrations. Within marine ecosystems, coastal waters consistently had higher concentrations of vitamin B12 than open ocean. Several studies have reported significant vertical stratification in both dissolved and particulate vitamin B12 fractions, which appears related to differences in production and/or degradation of vitamin B12 and the abundance of phyto- and bacterioplankton.  Particulate B12 concentrations were higher in spring and summer, while dissolved B12 peaked in winter and fall, likely due to increased phytoplankton biomass during the warmer months. This review provides an overview of analytical developments in vitamin B12 analysis, current concentration estimates, and identifies knowledge gaps and environmental factors linked to its dynamics.

Presentation Preference: Oral

Primary Presenter: Mohammad Salar Sohrabi, University of Eastern Finland (salar.sohrabi@uef.fi)

Authors:

Mohammad Salar Sohrabi, University of Eastern Finland  (salar.sohrabi@uef.fi)

Xuan Zhou, University of Eastern Finland  (xuan.zhou@uef.fi)

Sadikshya Ghimire, University of Eastern Finland  (sadikshya.ghimire@uef.fi)

Ursula Strandberg, University of Eastern Finland  (ursula.strandberg@uef.fi)