All the facts
There are three different water ecosystems. Oceans, Lakes, and Streams. To build an ocean you need salt water, waves, dolphins, star fish, sea weed, and flounder. Oceans are the largest of all water ecosystems. To build a stream you need fresh water, running water, trout, moss, cat fish, and cray fish. To build a pond you need fresh water, still water, salamanders, frogs, and leeches.
Many fish start their lives in Wetlands. Wetlands protect the world from things like big waves. The amount of water in a Wetland depends on the season. Sometimes Wetlands are salt water and sometimes it is fresh.
Most lakes are fresh water. Most lake form naturally when water flows into one spot. The amount of water depends on how much rain falls over time.
An ecosystem is all living things and all nonliving things in an area.