3.2 Aquatic Biomes

Notes

Aquatic biomes are classified mostly by salinity (salt content), depth, and flow.

• Freshwater (under 0.5% salt): lakes, ponds, rivers, streams, and wetlands.
• Marine (about 3.5% salt): open ocean, coral reefs, and the deep sea.
• Estuaries are where fresh river water meets salt water. They are nutrient rich and serve as nurseries for many fish.
• Wetlands (marshes, swamps, bogs) filter pollutants, absorb floods, and store carbon.
• Coral reefs are called the rainforests of the sea because they support huge diversity, but they are sensitive to warming and acidification.
• In lakes, the littoral zone is the shallow edge, the limnetic zone is open water with light, and the profundal zone is deep and dark.
• Example: a place where a river flows into the ocean, with brackish water, is an estuary.