Oligotrophic

An oligotrophic ecosystem or environment is one that offers little to sustain life. The term is commonly utilised to describe bodies of water or soils with very low nutrient levels. It derives etymologically from the Greek "oligo" (small, little, few) and "trophe" (nutrients, food).

Oligotrophic environments are of special interest for the alternative energy sources and survival strategies upon which life could rely.fact|date=March 2008

Examples

Antarctic

Lake Vostok, a freshwater lake which has been isolated from the world beneath 4 km of Antarctic ice for approximately 500,000 years [Priscu, JP, Adams, EE, Pearl, HW, Fritsen, CH, Dore, JE, Lisle, JT, Wolf, CF, Mikucki, JA. (2002) "Perennial Antarctic Lake Ice: A refuge for Cyanobacteria in an extreme environment" In "Life in Ancient Ice" (eds. Rogers, S and J Castello), Princeton Press;] is frequently held to be a primary example of an oligotrophic environment.

Australia

The sandplains and lateritic soils of southern Western Australia, where an extremely thick craton has precluded any geological activity since the Cambrian and there has been no glaciation to renew soils since the Carboniferous. Thus, soils are extremely nutrient-poor and most vegetation must use strategies such as proteoid roots to gain even the smallest quantities of such nutrients as phosphorus and sulfur.

The vegetation in these regions, however, is remarkable for its biodiversity, which in places is as great as that of a tropical rainforest and produces some of the most spectacular wildflowers in the world. It is however, severely threatened by climate change which has moved the winter rain belt south, and also by clearing for agriculture through use of fertilizers, which is primarily driven by low land costs that make farming economic even with yield a fraction of those in Europe or North America.

outh America

An example of oligotrophic soils are those on white-sands, with soil pH lower than 5.0, on the Rio Negro basin on northern Amazonia that house very low-diversity, extremely fragile forests and savannahs drained by blackwater rivers; dark water colour due to high concentration of tannins, humic acids and other organic compounds derived from the very slow decomposition of plant matter. [ Janzen. D. H. 1974. Tropical Blackwater Rivers, Animals, and Mast Fruiting by the Dipterocarpaceae. Biotropica, Vol. 6, N° 2 (Jul., 1974), pp. 69-103] [Sioli, Harald. 1975. Tropical rivers as expressions of their terrestrial environments. In: F.B. Golley & E. Medina (eds.) Tropical Ecological Systems/Trends in Terrestrial and Aquatic Research. pp 275-288] [German, Laura A. (December 2004) "Ecological praxis and blackwater ecosystems: a case study from the Brazilian Amazon" "Human Ecology: An Interdisciplinary Journal" 32(6): pp. 653-683;] Similar forests are found in the oligotrophic waters of the Patía River delta on the Pacific side of the Andes. [Del Valle-Arango, Jorge Ignacio (August 2003) "Cantidad, calidad y nutrientes reciclados por la hojarasca fina en bosques pantanosos del Pacífico sur colombiano." "Interciencia" 28(8): pp. 443-452 (in Spanish);]

See also

* Oligotroph Organism
* Oligotrophic lake
* Eutrophic lake

References

External links

* Special issue about [http://www.blackwell-synergy.com/toc/fwb/50/10 Lake oligotrophication] published in "Freshwater Biology"