A mass mortality event (MME) is an incident that kills a vast number of individuals 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]
^Rasnitsyn, Alexandr P., ed. (2002). History of insects (Reprint. ed.). Dordrecht, The Netherlands: Springer. p. 28. ISBN9781402000263. Retrieved 26 February 2018.