dieoff

Die-off is the rapid decline or collapse of a population of organisms or a component of an ecosystem, typically occurring over a short time frame and resulting in high mortality. Die-offs can involve a single species, multiple species, or entire communities, and they may follow acute disturbances or chronic stress. They are distinguished from slower, gradual declines due to long-term habitat loss or sustained exploitation.

Causes and mechanisms include disease outbreaks, toxins, extreme weather, habitat degradation, resource scarcity, and invasive species. Interactions among stressors can produce synergistic effects that push populations beyond recovery. Predation pressure, immune suppression, and environmental change can also contribute to die-offs, especially when resilience is limited.

Patterns and terminology: researchers describe 'mass mortality events' when mortality is unusually high over a short period. Die-offs may cascade through ecosystems, particularly when a keystone species or a critical resource is affected.

Examples: Sea star wasting disease led to widespread sea star deaths along the Pacific coast beginning in 2013. Chestnut blight, caused by Cryphonectria parasitica, caused the rapid decline of native American chestnut trees in the eastern United States during the 20th century. Coral reef die-offs associated with thermal stress have been evident in many regions during major warming events in recent decades. Kelp forest declines linked to warming, pollution, and herbivore dynamics have also been documented.

Implications: die-offs can alter community structure, reduce biodiversity, and affect ecosystem services such as fisheries, carbon storage, and coastal protection. Monitoring and research aim to identify drivers, interaction effects, thresholds, and potential recovery pathways.