What are invasive species? How do they affect the ecological balance of American Samoa’s ecosystem? Objective Students will be able to: 1. Define the vocabulary terms invasive species and conservation. 2. Identify four pests and explain their negative impact in American Samoa's ecosystems. 3. Describe how our actions can threaten the health of our ecosystems. 4. Learn about the role of the National Park of American Samoa in conserving our natural ecosystem. Background Some changes have benefited some wildlife species. For example, the introduction of several important food plants such as bread Duration: 60 Minutes.