Differences in Aquatic Ecosystems


  • Freshwater covers less than 1% of earth's surface, but is home to 35% of all vertebrate species.
  • In the United States nearly half of the 573 animals on the threatened and endangered species list are freshwater species.
  • More than 30 years after the Clean Water Act promised clean water, an overwhelming majority of Americans live within 10 miles of a polluted river, lake, or coastal water. These waterways are unsafe for fishing, swimming, or aquatic life.

Examples: The Amazon River, Mississippi River

Brackish Water

  • Brackish water or briny water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water.
  • The word comes from the Middle Dutch root "brak," meaning "salty". Certain human activities can produce brackish water, in particular certain civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming.
  • Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.

Examples: The Amazon Delta, The Mississippi River Delta

Salt Water

  • Saltwater ecosystems include a wide array of vastly different ecosystems, with at least one major similarity -- saltwater. The plant life, animal life and land structures that make up saltwater ecosystems also are varied. These ecosystems can best be characterized according to their locations.
  • Saltwater ecosystems can be divided into oceans, estuaries, coral reefs and shorelines; each of these having a diversity of characteristics.
  • All of saltwater ecosystems have landforms, plant life and animal life, which may be unique to their location. Although these saltwater ecosystems are very different, they share high degree of interdependency by the nature of their association.

Examples: Atlantic Ocean, Pacific Ocean