Marine Biogeochemical Cycles
Samantha B. Joye, Marshall W. Bowles, Kai Ziervogel
Abstract
Microorganisms catalyze elemental cycling in the ocean and regulate geochemical processes that are crucial for the maintenance of planetary habitability. This chapter provides an overview of marine carbon, oxygen, nitrogen, phosphorus, sulfur, and trace gas cycling with an emphasis on modern processes in pelagic and sedimentary habitats. Microorganisms couple oxidation and reduction reactions to extract energy from chemical disequilibria via thermodynamics. The ocean microbiome represents a reservoir of genetic diversity and metabolic potential. It performs the basic functions of this living planet and responds to chronic and acute external forcing in order to maintain these functions. This chapter reviews the biogeochemical cycles at local and regional scales and assesses how ocean biogeochemistry may be altered by global change. Climate change is having substantial impacts on the ocean. Ocean warming may alter the ocean’s microbiome. Biological interactions and distribution of plants, animals, and microorganisms will change to accommodate the new temperature and mixing regimes. Plankton moves with the water, and warming waters will exert a selective pressure on the microbiome, promoting the proliferation of microorganisms that are able to thrive under local conditions. Such changes in the microbiome may alter local and regional biogeochemistry.