Aquatic Biologist: Aquatic ecologist Studies plants and animals living in water, and environmental conditions affecting them: Investigates salinity, temperature, acidity, light, oxygen content, and other physical conditions of water to determine their relationship to aquatic life. Examines various types of water life, for example, plankton, worms, clams, mussels, and snails. May also specialize in the study of saltwater aquatic life and be designated Marine Biologist, or freshwater aquatic life and be designated Limnologist. May also specialize in culture, breeding, and raising of aquatic life, for example, shrimp, lobsters, clams, oysters, or fish, and commercial fish farm operations and be designated Aquaculturist.