Marine ecology and biodiversity is the scientific study of marine ecosystems in relation to their biotic and abiotic environment. Marine ecosystems have a large biodiversity and are essential for the sustenance of terrestrial and marine environments. This is because marine organisms are responsible for maintaining carbon, nitrogen, phosphorus and nutrient cycles as well as contributing significantly to the world's total photosynthetic output. Pollution caused by human activities, mostly through the widespread use of fertilizers and pesticides that flow into the oceans, has a drastic effect on the marine ecosystem. The presence of garbage, plastics and oils may result in an increase in ocean acidification and eutrophication. These effects are witnessed through a drop in productivity of marine ecosystems and a reduction in marine biodiversity. This book strives to provide a fair idea about marine ecology and marine biodiversity, as well as helps to develop a better understanding of the diverse aspects of these fields. The various studies that are constantly contributing towards advancing technologies and evolution of these fields are examined in detail. It is an essential guide for both academicians and those who wish to pursue these disciplines further.