Biological oceanography is the study of marine organisms, their quantitative distribution in time and space and their interactions with the ocean. In the first few weeks of this course, we explore the different size and functional classes of organisms that dwell in the upper ocean, with an emphasis on the dominant forms of phytoplankton, viruses, bacteria and archaea, and their grazers, the zooplankton. We examine factors controlling the distribution and abundance of marine organisms, and analyze some interactions of organisms with each other and with their environment. In the latter half of the course, we explore benthic communities and the deep ocean. We will also examine the influence of climate change and other perturbations on different oceanic ecosystems.