mass extinction

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As a mass extinction ( English mass mortality ) an extraordinary, dramatic loss of individuals of one or many will populations of a kind referred to in a short time. Depending on the triggering factor, many species or even entire communities can be affected.

Difference from mass extinction

In contrast to this, masses from dying denotes the extinction of numerous species in a relatively short period of time for evolution . Mass extinction can be associated with the extinction of the affected species or, in extreme cases, even with mass extinction, but this is not the rule. Both terms are sometimes used synonymously.

reasons

Mass extinctions can occur for a number of reasons. Documented cases include a .:

  • Infection with pathogens, e.g. B. Chytridiomycosis in numerous amphibian species
  • Unusual climatic factors, e.g. B. All corals in a reef die off due to coral bleaching , for example due to an increasing frequency and intensity of heat events
  • Weather events, e.g. B. Dying of migratory birds during unusual rainy or cold periods.
  • Synthetic environmental toxins, e.g. B. organochlorine compounds in dolphins, biocides (e.g. DDT )
  • natural toxins, e.g. B. Fish death due to red tides : mass proliferation of dinoflagellates in marine areas
  • social stress due to overpopulation, proven e.g. B. in an island population of sika deer

Mass extinctions are a sign that numerous organisms are simultaneously subject to ecological conditions to which they are not adapted. Although they also occur for natural reasons, it is not uncommon for human interventions in habitats to be responsible, which can drastically change living conditions in a short time. The causes of mass deaths are not always easily and clearly ascertainable. Often there is a trigger (e.g. a pathogen) and a different underlying cause (e.g. reduced vitality due to environmental toxins, overpopulation). Mass extinctions of a species can completely transform the ecology of a habitat. For example, after the mass extinction of a species of sea ​​cucumber off the California coast (due to an infectious disease), the kelp forests expanded into previously uninhabited stretches of coast . Reasons and effects can be indirect and therefore difficult to identify. Industrial and agricultural water pollution caused mass deaths of seagrass beds in Florida Bay . The mass reproduction of cyanobacteria triggered by the death of seagrass led (through released toxins) to the death of numerous sponges , which in turn are a crucial habitat for juvenile Caribbean lobster Panulirus argus . The decline in lobsters caused severe economic damage to the fishery.

See also

literature

Individual evidence

  1. ^ I. Newton (2007): Weather-related mass-mortality events in migrants. Ibis 149: 453-467. doi : 10.1111 / j.1474-919X.2007.00704.x
  2. Douglas W. Kuehl, Romona Haebler, Charles Potter (1991): Chemical residues in dolphins from the US Atlantic coast Including Atlantic bottlenose Obtained during the 1987/88 mass mortality. Chemosphere Volume 22, Issue 11: 1071-1084. doi : 10.1016 / 0045-6535 (91) 90308-Z
  3. JL Maclean (1989): Indo-Pacific red tides, 1985–1988. Marine Pollution Bulletin Volume 20, Issue 7: 304-310. doi : 10.1016 / 0025-326X (89) 90152-5
  4. John J. Christian, Vagn Flyger, David E. Davis (1960): Factors in the mass mortality of a herd of sika deer, Cervus nippon. Chesapeake Science Volume 1, Number 2: 79-95, doi : 10.2307 / 1350924
  5. ^ JS Pearse & AH Hines (1979): Expansion of a Central California Kelp Forest Following the Mass Mortality of Sea Urchins. Marine Biology Volume 51, Number 1: 83-91 doi : 10.1007 / BF00389034
  6. ^ RJ Livingston (1987): Historic trends of human impacts on seagrass meadows in Florida. Proceedings of the symposium on subtropical-tropical seagrasses of the southeastern United States; August 12, 1985. Gainesville, Florida. (Ed .: Florida Fish and Wildlife Conservation Commission): 139-151.
  7. MJButler IV, JH Hunt, WF Herrnkind, MJ Childress, R. Bertelsen, WC Sharp, TR Matthews, JM Field, HG Marshall (1995): Cascading disturbances in Florida Bay, USA: cyanobacteria blooms, sponge mortality, and implications for juvenile spiny lobsters Panulirus argus. Marine Ecology Progress , Series 129: 119-125.