Why is this keystone species important to the biome/ecosystem?

Refer to the infographic provided and chose a biome to describe with an example ecosystem. Provide one example of a keystone species found in the biome/ecosystem. Why is this keystone species important to the biome/ecosystem? What defines it as a keystone species? Provide an example of an invasive species found in the biome/ecosystem. What are some of the negative impacts this invasive species has on the ecosystem? What is being done to mitigate impacts? Provide one example of an endangered species found in the biome/ecosystem. Briefly discuss the causes of the decline in the species and what is being done to help.