How did trans-Atlantic slavery most affect the population of Africa

The continent ran out of human resources, and this weakened the economic stability.

Explanation:

The most important reason is that the African continent ran out of its human resources that were much needed back then, since their economy was based on hard physical work. The main countries trading slaves with Africa were: the French, the British, the Portuguese, and the Spanish. They reached their goal of trading people by entering the war. War was the easiest way to enslave people, because it weakened any country's stability. Also, it directly affected the economy by making only some people wealthier, which meant that some were becoming wealthier, and the majority was becoming poorer.

There were fewer men to clear fields and hunt.