1. Scientific study of organisms in the ocean or other marine or brackish bodies of water. (wikipedia.com)
2. Branch of biology that deals with the study of ocean ecosystems, plants, animals, and other living beings.
3. Study of ocean plants and animals and their ecological relationships (biology-online.org)
4. The branch of biology dealing with organisms that live in the sea. (wikitionary.com)
Syn: biological oceanography