This book proposes a system for emergency red tide monitoring for harbors derived from long-term toxic red tide tracking and early warning systems in Xiamen's seas. The work presents early warning and prevention recommendations that can be used by the marine management ministries and organisations for both early warning decision-making as well as emergency monitoring of harbor ocean red tide disasters.This book covers the design of a decision support system to monitor red tides in harbors, with indications on their toxicity and their impact on the eutrophication of harbor water, to detect and monitor red tides as well as warn inhabitants of impending red tide invasions. This work also provides insight into understanding marine ecology.