Wanderlust World Wanderlust World Open oceans make up the largest marine ecosystems, but ironically, they shelter the fewest species per volume in that area. Open ocean water can reach from 200 to 11,500 m and lies above the continental shelf. Open ocean areas are great producers of phytoplankton, which makes its own food through photosynthesis.
Estuaries are areas which are partially enclosed from the open ocean, where freshwater mixes with salt. Estuaries can be located at the mouth of a river, where it hits the ocean, or they can exist in the form of lagoons, where the free flow of water is limited from a sand bar or coral reef. Many species use estuaries as nurseries, raising their young there until they are old enough to travel into the open ocean. Additionally, estuaries play an important part in filtering and cleaning waters of pollutants because they are highly populated with plants and animals that can ingest high amounts of toxins.
Coral reefs occur in areas that are shallow or clear enough that sunlight can reach corals, generally tropical areas. Extremely fragile in nature, they also represent some of the most biodiverse ecosystems in the world. According to the United States Agency of International Development (USAID), coral reefs make up just 0.02 percent of the ocean and yet shelter one-third of the marine life on the planet.
The area where the ocean meets the continental margin is known as a coastal area. This ecosystem is one of the most important for humans, because it produces the most fish, shellfish and seaweed. Additionally, coastal areas convert large amounts of carbon dioxide to oxygen because they house great amounts of phytoplankton.
Upwelling continental shelves, ecosystems generally found at the eastern edge of oceans, are important producers of small pelagic fish. These areas support large schools of small fish so well because they generally have particularly nutrient-rich waters, pushed to the surface by wind in a process called upwelling.