Biological Oceanography is concerned with the interactions of populations of marine organisms with one another and with their physical and chemical environment. Because these interactions are frequently complex, and because the concepts and techniques used are drawn from many fields, biological oceanography is of necessity, interdisciplinary. Knowledge of physical and geological oceanography is pertinent.
Hydra picture, taken by Thomas Bosch, is found at the Cnidaria Home Page.
Physical Oceanography is the study of the physical processes in the ocean and the interaction of the ocean with the atmosphere. Physical oceanographers study currents, tides, waves, and convection in the deep ocean, along coasts, and in the surf zone. They also study the heat budget of the ocean including solar heating, evaporation, infrared radiation into and out of the sea, and the transport of heat and salt by currents. The goal of their work is to understand and predict the processes including such important processes as El Niño, tsunamis, tides, the role of the ocean in climate and the ice ages, and the influence of the oceans on local climate. In doing their work they often construct elaborate numerical models of the circulation, and they develop instruments used on ships and satellites. The following map depicts global sea surface temperature.
From Texas A&M University's Physical Oceanography Page.
Geological Oceanography is the study of the geology of the lands covered by water, just as geologists have tried to understand the geology of the lands ashore. Marine geologists compile data about the topography or shape of the ocean floors, the distribution and type of bottom sediments, the composition and structure of the underlying rocks, and the geologic processes (plate tectonics theory) that have been at work throughout the seafloor's history. Using this information,marine geologists assess the mineral resources of the seafloor, predict the location of certain hazards, investigate marine geologic processes, and add to our overall scientific understanding of Earth. The following map depicts the geology of the seafloor. Areas in red are the areas of most recent formation
Chemical Oceanography is the study of chemical processes in the ocean. It includes the study of the salinity of the ocean: the role of the ocean in global chemical balances of carbon, nitrogen, and other important atmospheric gases; the fate of chemicals carried into the ocean by rivers; the carbonate system; chemical processes influencing biological productivity including nutrients, dissolved organic matter, and trace elements; hydrothermal vent chemical systems; and the use of chemical tracers such as tritium and chloroflourocarbons used to study the ocean's circulation; and the use of chemical isotopes for studying oceanic processes and dates.
Salinity map produced by the USGS