An Aquatic Ecosystem is an Ecosystem Located in a Body of Water
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An aquatic ecosystem is an ecosystem located in abody of water. Communities oforganisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types ofaquatic ecosystems are marine ecosystems and freshwater ecosystems. Main article: Marine ecosystem Marine ecosystems cover approximately 71% of the Earth's surface and contain approximately 97% of the planet's water. They generate 32% of the world's net primary production. [1] They are distinguished from freshwater ecosystems by the presence of dissolved compounds , especially salts, in the water. Approximately 85% of the dissolved materials in seawaterare sodium and chlorine. Seawater has an average salinity of 35parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems. [2] Marine ecosystems can be divided into the following zones: oceanic (the open part of the ocean where animals such as whales, sharks, and tuna live); profundal (bottom or deep water); benthic (bottom substrates); intertidal (the area between high and low tides); estuaries ; salt marshes;coral reefs; and hydrothermal vents (where chemosynthetic sulfurbacteria form the food base). [1] Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals,cephalopods , echinoderms , and sharks. Fish caught in marine ecosystems are the biggest source ofcommercial foods obtained from wild populations. [1] Environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources (for example overfishing of certain species), marine pollution, climate change, and building on coastal areas. [1] [edit] Freshwater Main article: Freshwater ecosystem Freshwater ecosystems cover 0.80% of the Earth's surface and inhabit 0.009% of its total water. They generate nearly 3% of its net primary production. [1] Freshwater ecosystems contain 41% of the world's known fish species. [3] There are three basic types of freshwater ecosystems: • Lentic: slow-moving water, including pools, ponds, and lakes. • Lotic: rapidly-moving water, for example streams and rivers. • Wetlands: areas where the soil is saturated or inundated for at least part of the time. [4] Lake ecosystems can be divided into zones: pelagic (open offshore waters); profundal; littoral (nearshore shallow waters); and riparian (the area of land bordering a body of water). Two important subclasses oflakes are ponds, which typically are small lakes that intergrade with wetlands, and waterreservoirs. Many lakes, or bays within them, gradually become enriched by nutrients and fill in with organic sediments, a process called eutrophication . Eutrophication is accelerated by human activity within the watercatchment area of the lake. [1]
