These fluctuations may also affect the predators that feed on these prey items, such as wolves, foxes and owls. These predators must either find an alternate source of prey or risk starvation and death. Ecological Succession. When changes to either abiotic or biotic factors affect an entire ecosystem, ecological succession occurs.
A temporary decrease in blood flow to the brain results in unconsciousness, or fainting. Many disorders, some of them serious, can cause this.
1 Common causes of fainting include heat, pain, distress, the sight of blood, or anxiety and hyperventilating. 2  Lying the person down will often improve the personâs condition.  Frequent fainting spells need to be medically investigated to check for underlying causes.