The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.
B! The strongest characteristics will survive when the weak ones won't
It is useful for an ecologist to identify the keystone species in an ecosystem because the keystone species is important to maintaining the stability of an ecosystem, and any changes in the keystone species population shows that there is changes in ecosystem health.
Answer:
1.) A factory produces chemical waste and releases it into a water system
2.) Water becomes polluted in nearby rivers and streams
3.) Aquatic plants stop thriving
4.) Small fish do not have adequate food
5. Larger fish have less prey to eat and their numbers decline
