The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.
Water containing no significant amounts of salts, such as water from RIVERS and LAKES.
Inland bodies of still or slowly moving FRESH WATER or salt water, larger than a pond, and supplied by RIVERS and streams.
A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)