Water ecosystems are all around us. Some examples of water ecosystems include Ponds, Rivers, Streams, e.t.c. Water Ecosystems need two things to be called a water ecosystem. They need living and non-living things like dead trees or living fish. There are two types of water ecosystems. These include freshwater and saltwater ecosystems. Did you know a log can be a water ecosystem? well it can! like i said earlier all a water ecosystem needs is a water source and living and non-living things. What do animals in water ecosystems? living animals like fish or whales have to eat to. Well, sharks eat fish, fish eat smaller fish, smaller fish eat plankton and plankton eat phytoplankton. What is a wetland? A wetland is a water ecosystem. But at times it can be flooded or dry.