The microbial loop refers to the small microscopic organisms in the ocean – viruses, bacteria, the small phytoplankton and microzooplankton – and the relationships between them.
NIWA biological oceanographer Dr Julie Hall explains how the microbial loop forms the bottom of marine food webs and involves rapid cycling of both nutrients and carbon. Dominance of the microbial loop in the upper waters of the ocean leads to less carbon sequestration (sinking of carbon to the deep ocean).