Hydrobiology is the study of living organisms that live in water or depend on water for their existence. Some synonyms for hydrobiology include aquatic biology, marine biology, limnology, oceanography, and freshwater biology. Aquatic biology is the study of all life forms ranging from bacteria to whales in all types of aquatic environments. Limnology examines freshwater systems such as rivers, lakes, and wetlands. Oceanography deals with the physical and chemical characteristics of the ocean environment and how it affects marine organisms. Freshwater biology studies the ecology and physiology of aquatic plants and animals in freshwater ecosystems. In a nutshell, hydrobiology encompasses a broad range of studies that focus on the biology of organisms living in aquatic environments.