A narrative that attempts to cover three major disciplines of oceanography -- marine geology and geophysics, physical oceanography, and marine chemistry and geochemistry -- should be prefaced with the explanation that these sub-fields of oceanography are related. Oceanographers and others involved in these disciplines often work together to unravel the mysteries and unknowns of ocean science. In many government-sponsored research efforts, preference is given to projects that integrate the separate disciplines of oceanography and incorporate important principles from each to better understand a system, phenomenon, event, or process.
As a growing global population stresses the ability of our society to produce food, water, and shelter, we will continue to look to the oceans to help sustain our basic needs. Advances in technology, combined with demand, will improve our ability to derive food, drinking water, energy sources, waste disposal, and transportation from the ocean. It will be up to this and future generations to build upon our existing knowledge of the ocean and its potential to help meet the needs of the world and its inhabitants.
In reading about each of these sub-fields, keep in mind that some of the most important oceanographic discoveries have been made as a result of an integrated, multidisciplinary approach, often involving geologists, chemists, biologists, physical oceanographers, and engineers.
The 1977 discovery of active hydrothermal vent communities illustrates the benefits of this multidisciplinary approach. At these active hydrothermal vent sites, oceanographers observed thriving populations of hundreds of "new" species, including tube worms and giant clams. "Black smoker" chimneys also were observed, venting hot, metal-rich fluid that generates from within the Earth's crust and can reach temperatures as high as 350°C. Just outside these chimney-like structures, the water is much cooler -- about 2°C -- and has a higher pH. When these fluids meet, a reaction takes place and forms black "smoke." Although the vent sites are located at the bottom of the ocean floor where there is no light, life is plentiful. Scientists discovered that the chemistry of the water at these vent sites provides energy for bacteria to grow by chemosynthesis, in much the same way sunlight provides energy for plants to grow by photosynthesis.