Aquatic Ecosystems

Jay Flores and Katie Bland

Freshwater Ecosystems

Only 3% of the Earth's water is fresh. The majority of the Earth's freshwater in frozen in glaciers but the rest makes up ponds, lakes, and rivers. Freshwater can be divided into three zones, the littoral zone, limnetic zone, and the profundal zone. The littoral zone is closest to the shore and light reaches the bottom on the zone. It consists of many tiny crustaceans, flatworms, snails, frogs, and fish. The Limnetic zone is the layer of open water where photosynthesis can occur. The profundal zone is the deepest point of the body of water where no light reaches. Marine Biologists are scientists who study these different bodies of water.

Brackish Water

Brackish water has a higher salt content then freshwater, but less than salt water. It is found is estuaries and in brackish fossil aquifers. However, the Baltic Sea and the Caspian Sea both contain brackish water. Many of these bodies of water are studied by limnologists. Limnologists study inland water systems such as lakes, and marshes.


Salt Water

Nearly three quarters of the Earth is covered by saltwater. Oceans make up 97% of the Earth's water. The ocean floor is so deep that almost 90% of the Ocean has currently gone undiscovered known as the "abyss".