Freshwater ecosystems include rivers, lakes, ponds, and wetlands. These environments are characterized by low salt concentrations and support a variety of plant and animal life, such as fish, frogs, and water lilies. Freshwater ecosystems play a crucial role in the water cycle and provide habitats for many species. Marine ecosystems, on the other hand, encompass oceans, coral reefs, and estuaries. They are characterized by higher salt concentrations and are home to diverse organisms, including sharks, whales, and sea turtles. Marine ecosystems are vital for global climate regulation and support a significant portion of the world's biodiversity.