Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disastrous event occurring on a short time scale. Ecosystems have the ability to rebound from a disruptive agent. The difference between collapse or a gentle rebound is determined by two factors —- the toxicity of the introduced element and the resiliency of the original ecosystem.