Sugar was a huge cause of the Atlantic slave trade. the Europeans established many sugar plantations in the Mediterranean . the danger of the work, the absence of wage workers, and limitations attached to serf labor led to slavery as a source of labor. The Slavic supply of slaves was cut off when the ottoman empire seized Constantinople. native Americans quickly perished from European diseases, and marginal Europeans were Christians and so exempt from slavery which left Africans as the source of slaves. they had immunity to tropical and European diseases as well as agricultural skills.