CHAPTER 2:Oceanic Nickel Biogeochemistry and the Evolution of Nickel Use

Nickel (Ni) catalyzes vital reactions in modern biogeochemical cycles, and it is likely that its role as a metal cofactor evolved in the early Archean when enhanced submarine volcanism supplied abundant Ni to seawater. This chapter provides a holistic summary of Ni ocean biogeochemistry and the diverse marine microorganisms that rely on Ni to catalyze globally important chemical reactions, from surface seawater to deep seafloor sediments to volcanic vents. We highlight poorly recognized Ni requirements for the carbon and nitrogen cycle, and provide a new compilation of the growth response of diverse microbial taxa to varying Ni concentrations in the context of changing ocean chemistry. Finally, we discuss current hypotheses for the co-evolution of Ni enzymes and seawater bioavailability over Earth history.