Section 1: General considerations -- Chapter 1. Physical and chemical processes of marine environment -- Chapter 2. A review study on the microbes in the recycling of carbon -- Chapter 3. Microbial symbiosis in marine ecosystem -- Section 2: Communities of special interest -- Chapter 4. Cyanobacteria in oceanChapter -- Chapter 5. Marine algae and their importance -- Chapter 6. Antarctica microbial communities: ecological and industrial importance -- Chapter 7. Crustaceans - microbes and defense mechanisms -- Section 3: Marine microorganisms and environmental bioremediation -- Chapter 8. Pollution in marine ecosystem: impact and prevention -- Chapter 9. Source and effect of oil spills on associated microorganisms in marine aquatic environment -- Chapter 10. Heavy metal pollution in water: cause and remediation strategies -- Chapter 11. Responses of marine fungi to heavy metal contamination -- Chapter 12. Micro-plastic pollution in marine ecosystem and its remediation -- Chapter 13. Microplasticpollution in aquatic environment: ecotoxicological effects and bioremediation prospects -- Chapter 14. Biodegradation of endocrine-disrupting chemicals using marine microorganisms -- Chapter 15. Bioreactors for bioremediation of polluted water -- Section 4: Others applications and perspectives -- Chapter 16. Industrial importance of marine algae -- Chapter 17. Sargassum derived agents for potential cosmetic applications -- Chapter 18. Utilization of seaweed as partial replacement to the fish meal in aquaculture diets -- Chapter 19. Nanobiotechnology of marine organisms: mechanisms and applications -- Chapter 20. Bioactive compounds from marine water ecosystem -- Chapter 21. Marine fish microbiome: current status and future perspectives.