What is "refugium"

n. 1 Any local environment that has escaped regional ecological change and therefore provides a habitat for endangered species. 2 (cx aquaculture English) A separate section of a fishtank that shares the same water supply, used for denitrification, plankton production, etc.

In biology, a refugium (plural: refugia), sometimes termed simply a refuge or just a "fuge", is a location of an isolated or relict population of a once more widespread species. This isolation ( allopatry) can be due to climatic changes, geography, or human activities such as deforestation and overhunting.

Present examples of refuge species are the mountain gorilla, isolated to specific mountains in central Africa, and the Australian sea lion, isolated to specific breeding beaches along the south-west coast of Australia, due to humans taking so many of their number as game. This resulting isolation, in many cases, can be seen as only a temporary state; however, some refugia may be longstanding, thereby having many endemic species, not found elsewhere, which survive as relict populations. The Indo-Pacific Warm Pool has been proposed to be a longstanding refugium, based on the discovery of the "living fossil" of a marine dinoflagellate called Dapsilidinium pastielsii, currently found in the Indo-Pacific Warm Pool only.

In anthropology, refugia often refers specifically to Last Glacial Maximum refugia, where some ancestral human populations may have been forced back to glacial refugia, similar small isolated pockets in the face of the continental ice sheets during the last glacial period. Going from west to east, suggested examples include the Franco-Cantabrian region (in northern Iberia), the Italian and Balkan peninsulas, the Ukrainian LGM refuge, and the Bering Land Bridge. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the glacial maxima (incl. the Last Glacial Maximum) in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense forest cover.

In fishkeeping, a refugium is an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply. It is a separate sump, connected to the main show tank. It is a " refugium" in the sense that it permits organisms to be maintained that would not survive in the main system, whether food animals, anaerobic denitrifying bacteria, or photosynthesizers. For some applications water flow is limited in order to protect plants or animals that require slow flow. The refugium light cycle can be operated opposite to the main tank, in order to keep total system pH more stable (due to the uptake of acid-forming CO by photosynthesis occurring in the refugium during its "daylight" hours). One volume guideline for a refugium is 1:10 main tank volume.

A refugium may be used for one or more purposes such as denitrification, nutrient export, plankton production, circulation, surface agitation to improve oxygen exchange with the atmosphere or even aesthetic purposes.

Refugium may refer to:

• Refugium (Latin), the meaning of the word "refugium" is refuge or hideaway; in some cases known as wellness area for relaxation and recovering.
• Refugium (fishkeeping), an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply
• Refugium (population biology), a location of an isolated or relict population of a once widespread animal or plant species
  • Last Glacial Maximum refugia specifically, in anthropology
• Refugium Range, a mountain range on Vancouver Island, British Columbia, Canada