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Farms create conditions for the spread of disease and parasites and , through the escape of farmed fish , introduce invasive species . Domestic , industrial and agricultural effluents are problems in most sub-regions , especially around large urban or industrial coastal centres , and in Western and Central Africa where commercial plantations are common in the coastal zone . In spite of considerable efforts and significant achievements , many of the problems , which plagued the Earth during the 20th Century , still linger . These disasters have displaced populations across national borders and internally , contributing to further environmental degradation , and leading to more vulnerability and insecurity . A number of important contributions to the study of Garibaldi have been prepared and published under the auspices of the International Institute of Garibaldian Studies .