Marine ecosystems are among the largest of Earth's aquatic ecosystems. They include oceans, salt marsh and intertidal ecology, estuaries and lagoons, mangroves and coral reefs, the deep sea and the sea floor. They can be contrasted with freshwater ecosystems, which have a lower salt content. Marine waters cover two-thirds of the surface of the Earth. Such places are considered ecosystems because the plant life supports the animal life and vice-versa. See food chains.
Marine ecosystems are very important for the overall health of both marine and terrestrial environments. According to the World Resource Center, coastal habitats alone account for approximately 1/3 of all marine biological productivity, and estuarine ecosystems (i.e., salt marshes, seagrasses, mangrove forests) are among the most productive regions on the planet. In addition, other marine ecosystems such as coral reefs, provide food and shelter to the highest levels of marine diversity in the world.
Marine ecosystems usually have a large biodiversity and are therefore thought to have a good resistance against invasive species. However, exceptions have been observed, and the mechanisms responsible in determining the success of an invasion are not yet clear.
See also 
- Aquatic ecosystem
- Aquatic toxicology
- Blue carbon
- Large marine ecosystem
- Marine biology
- Marine habitats
- Tropical marine climate
- Marine Ecosystems | Biological Indicators of Watershed Health | US EPA
- Stachowicz, Fried, Osman, Whitlatch ESA Online Journals - BIODIVERSITY, INVASION RESISTANCE, AND MARINE ECOSYSTEM FUNCTION: RECONCILING PATTERN AND PROCESS. http://www.esajournals.org/doi/abs/10.1890/0012-9658%282002%29083%5B2575%3ABIRAME%5D2.0.CO%3B2?journalCode=ecol.
Further reading 
- Barange M, Field JG, Harris RP, Eileen E, Hofmann EE, Perry RI and Werner F (2010) Marine Ecosystems and Global Change Oxford University Press. ISBN 978-0-19-955802-5
- Boyd IL, Wanless S and Camphuysen CJ (2006) Top predators in marine ecosystems: their role in monitoring and management Volume 12 of Conservation biology series. Cambridge University Press. ISBN 978-0-521-84773-5
- Davenport J (2008) Challenges to Marine Ecosystems: Proceedings of the 41st European Marine Biology Symposium Volume 202 of Developments in hydrobiology. ISBN 978-1-4020-8807-0
- Levner E, Linkov I and Proth J (2005) Strategic management of marine ecosystems Springer. Volume 50 of NATO Science Series IV. ISBN 978-1-4020-3158-8
- Mann KH and Lazier JRN (2006) Dynamics of marine ecosystems: biological-physical interactions in the oceans Wiley-Blackwell. ISBN 978-1-4051-1118-8
- Moustakas A and Karakassis I (2005) "How diverse is aquatic biodiversity research?" Aquatic Ecology, 39: 367-375.]
- Marine Ecosystems US Environmental Protection Agency.
- Marine ecosystem (2008). In Encyclopædia Britannica. Retrieved October 11, 2008, from Encyclopædia Britannica Online.
- Smithsonian Ocean Portal