This book presents a comprehensive review of the most recent studies on the impact of contaminants on the marine environment. Conventional and new information, as well as the latest techniques, are presented, which can be applied to several types of marine organisms from bacteria and fungi to animals and algae. Specific topics discussed include the impact of different contaminants on different organisms as well as different approaches and their outcomes in terms of impact assessment. The integration of these techniques is also discussed in order to attain sentinel species and biomarkers to be applied for assessing ecological quality and impact assessment programs and studies.