Aquatic systems refer to environments where water is the primary medium for life. These systems can be classified into two main types: freshwater and marine. Freshwater systems include rivers, lakes, and wetlands, while marine systems encompass oceans and seas. Each type supports a diverse range of organisms, from tiny plankton to large whales. These ecosystems play crucial roles in the Earth's climate and water cycle. They provide habitats for wildlife, help regulate temperatures, and filter pollutants. Additionally, aquatic systems are vital for human activities, including fishing, transportation, and recreation, making their conservation essential for sustainability.