As late as the beginning of the nineteenth century, despite the many years of direct contact with European traders and the influx of European goods, most African societies still produced their own iron and its products, or obtained them from neighbouring communities through local trade. The quality of iron products was such that, despite competition from European imports, local iron production survived into the early twentieth century in some parts of the continent. This was the case at Yatenga in modern-day Burkina Faso, where in 1904 there were as many as 1,500 smelting furnaces in production. The production process covered prospecting, mining, smelting and forging. Different types of ore were available all over the continent and were extracted by shallow or alluvial mining. A variety of skills were required for building furnaces, producing charcoal, smelting and forging iron into goods. Iron production was generally not an enclave activity but a process that fulfilled the totality of socio-economic needs. It also fitted the gender division of labour within communities.
Answer:The population of unionid mussels in the Hudson River decreased after zebra mussels were introduced. Zebra mussels, a nonnative species, competed with the unionid mussels for food. The zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. The unionid mussel population decreased due to a lack of food.
