Mass mortality event

A mass mortality event (MME) is an incident that kills a vast number of a single species in a short period of time.[1] The event may put a species at risk of extinction or upset an ecosystem.[2] This is distinct from the mass die-off associated with short lived and synchronous emergent insect taxa which is a regular and non-catastrophic occurrence.[3]

Causes of MME's include disease and human-related activities such as pollution. Climatic extremes and other environmental influences such as oxygen stress in aquatic environments play a role, as does starvation. In many MME's there are multiple stressors.[2] An analysis of such events from 1940 to 2012 found that these events have become more common for birds, fish and marine invertebrates, but have declined for amphibians and reptiles and not changed for mammals.[4]

Examples of mass mortality events

In the Inyo National Forest there are several records of large numbers of migrating mule deer falling to their deaths by slipping on ice while crossing mountain passes. This has occurred when heavy snowfalls have persisted until fall, and have been turned to ice by frequent thawing and freezing.[5] In 2003 a rain-on-snow event encased the ground in ice, resulting in the starvation of 20,000 muskoxen on Banks Island in the Canadian Arctic.[6][7]

In 2015, some 200,000 saiga antelope died within a period of one week in a 20 km2 area of the Betpak-Dala desert region of Kazakhstan. They had gathered in large groups for their annual calving. It was determined that warm and humid temperatures had caused Pasteurella multocida, a bacteria that normally live harmlessly in their tonsils, to cross into their bloodstream and cause Hemorrhagic septicemia. This event wiped out 60% of the population of this critically endangered species. Mass mortality events are not uncommon for saiga. In 1981, 70,000 died, in 1988 there were 200,000 deaths and more recently in 2010 12,000 died.[8][2]

In 1988, the death of 20,000 harbour seals in the North Sea was found to be due to phocine distemper virus. Ten years later two bacteria were implicated in the death of 1600 New Zealand sea lions. On Marion Island in 2007, some 250–300 adult male Subantarctic fur seal died in a two-week period. It was suggested but not proven that this gender-biased mortality was caused by Streptococcus sanguinis which was carried by the house mouse, an alien species accidentally introduced in the 1800s.[9]

See also

References

  1. ↑ Fey, Samuel B.; Siepielski, Adam M.; Nusslé, Sébastien; Cervantes-Yoshida, Kristina; Hwan, Jason L.; Huber, Eric R.; Fey, Maxfield J.; Catenazzi, Alessandro; Carlson, Stephanie M. (27 January 2015). "Recent shifts in the occurrence, cause, and magnitude of animal mass mortality events". Proceedings of the National Academy of Sciences. 112 (4): 1083–1088. doi:10.1073/pnas.1414894112. PMC 4313809. Retrieved 26 February 2018.
  2. 1 2 3 Derbyshire, David (25 February 2018). "The terrifying phenomenon that is pushing species towards extinction". The Guardian. Retrieved 25 February 2018.
  3. ↑ Rasnitsyn, Alexandr P., ed. (2002). History of insects (Reprint. ed.). Dordrecht, The Netherlands: Springer. p. 28. ISBN 9781402000263. Retrieved 26 February 2018.
  4. ↑ Lee, Jane J. (14 January 2015). "Mass Animal Die-Offs Are on the Rise, Killing Billions and Raising Questions". National Geographic. Retrieved 25 February 2018.
  5. ↑ Rea, Sarah (22 Nov 2017). "A Slippery Slope". The Sheet. Retrieved 25 February 2018.
  6. ↑ Putkonen, Jaakko; Grenfell, Thomas C.; Rennert, Kevin; Bitz, Cecilia; Jacobson, Paul; Russell, Don (30 June 2009). "Rain on Snow: Little Understood Killer in the North". Eos. 90 (26): 221–222. doi:10.1029/2009EO260002. Retrieved 25 February 2018.
  7. ↑ Berger, J.; Hartway, C.; Gruzdev, A.; Johnson, M. (18 January 2018). "Climate Degradation and Extreme Icing Events Constrain Life in Cold-Adapted Mammals". Scientific Reports. 8 (1). doi:10.1038/s41598-018-19416-9. Retrieved 25 February 2018.
  8. ↑ "Catastrophic Collapse of Saiga Antelopes in Central Asia". UN Environment. Retrieved 25 February 2018.
  9. ↑ de Bruyn, P. J. Nico; Bastos, Armanda D. S.; Eadie, Candice; Tosh, Cheryl A.; Bester, Marthán N.; Hansen, Dennis Marinus (19 November 2008). "Mass Mortality of Adult Male Subantarctic Fur Seals: Are Alien Mice the Culprits?". PLoS ONE. 3 (11): e3757. doi:10.1371/journal.pone.0003757. Retrieved 26 February 2018.
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