Your narrowed down topic is "The effect of losing an endangered species in the Amazon." Therefore, you should focus on the geographical area of the Amazon rainforest. You may want to research and focus on a specific endangered species that is found in the Amazon and explore the impact that its loss would have on the ecosystem, the food chain, and the balance of nature. Additionally, you could research the social, economic, and cultural impact of losing an endangered species on the communities that depend on the Amazon rainforest for their livelihoods.