Final answer:
Freshwater, ocean, and terrestrial ecosystems are distinct categories of ecosystems. Freshwater ecosystems include lakes and rivers and have less than 1% salt. Ocean ecosystems are divided into shallow ocean, deep ocean water, and deep ocean bottom ecosystems. Terrestrial ecosystems are land-based and include various habitats such as forests, grasslands, deserts, and tundras.
Step-by-step explanation:
There are three broad categories of ecosystems: freshwater, ocean water, and terrestrial. Freshwater ecosystems include lakes, rivers, streams, and springs, and have less than 1% salt. Ocean ecosystems are the most common and are divided into shallow ocean, deep ocean water, and deep ocean bottom ecosystems. Terrestrial ecosystems are land-based and include forests, grasslands, deserts, and tundras.