Marine microbial hotspots—especially related to corals

Coral reefs, an oasis of the marine ecosystem, harbor millions of microorganisms. They are among the most diverse and productive, yet one of the most threatened ecosystems on the Earth. Ideally, coral reefs are considered as “rain forests of the sea” because they have a comparable primary production rate with rain forests. Although they represent approximately less than 0.1% of the total ocean surface and host nearly 25% of marine species. Corals are known to rely on diverse free-living and associated microbial consortium to drive the recycling of nutrients and support the sustainability of marine life. In addition, microbial diversity also maintains the holobiont health and resilience of ecosystems in tremendous environmental stress such as anthropogenic disturbances. Consequently, restoration and introduction of microbial diversity in the oceans are of utmost importance in order to effectively conserve and build the coral reefs. Recently, significant studies have been made on the profiling of associated diverse microbial consortia. This chapter dictates the overview of cataloging of microbial diversity with respect to the marine hotspots especially considering the corals.