Biological oceanography is the scientific study of how organisms, especially microorganism, are effected by the physics, chemistry, and geology of the oceans. It is very similar to marine biology, but more focused on a bottom to top approach (in terms of the food chain), whereas marine biology often works from top to bottom. All oceanographers must have knowledge of biology, chemistry, geology, and physics in order to understand the totality of the world's oceans.
The main focus of biological oceanography is often plankton. The productivity, and diversity of plankton can often provide clues as to the overall health of the ocean. Overall, the goal of biological oceanography is the understanding of what controls the abundance, kinds, and variations of the organisms in the ocean, attempting to gain a mechanistic understanding of the sea.
Biological oceanographers, along with marine biologists, study the plants and animals in the ocean environment. Employing field observations, computer models, and laboratory experiments, these scientists explore how various organisms interact with their changing environment. Main areas of research in biological oceanography include the microbiology of extreme environments, such as the high pressure deep, phytoplankton ecology, which studies the diversity of what are the primary producers of the ocean, and food web dynamics, which examines interactions between zooplankton, phytoplankton, and protists.