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Ecological importance of cyanobionts (KM)
Cyanobionts, cyanobacterial symbionts, can utilize light at low level by their flexible photosynthetic apparatus, which make them can symbioses with a wide range of organisms .Two major rules of cyanobionts play in symbiosis are “chloroplasts” and “nitrogen fixer”, which has more important in the oligotrophic waters that is nutrient depleted. The most common marine organisms harboring cyanobacteria are corals, diatoms and dinoflagellates.

Specific instance of cyanobionts with marine organism, functional rules and its ecologic impact of cyanobionts play in common marine organisms are elaborated below:

Coral

Coral are known for their symbiotic relationships with zooxanthellae, unicellular organisms with a spherical shape, which belong to members of the phylum dinoflagellate and has the most common genus Symbiodinium. Zooxanthellae work as “chloroplast” and help coral harvest light to meet corals’ carbon and energy needs. Zooxanthellae give coral the color and disruption of this relationship will cause coral bleaching, mainly because zooxanthellae are poorly adapted to temperature increases than their host.

Diatom

Many diatoms that survive in low-nutrient waters has a close association with cyanobacteria. Richelia intracellularis and Calothrix rhizoso-leniae are filamentous heterocystous cyanobacteria which symbioses with several diatom genera, including Hemiaulus, Rhizosolenia and Chaetoceros. Cyanobacteria provided fixed nitrogen to their nitrogen-limited hosts diatoms which help maintain the population of diatoms and supported the upper-level organisms.

Dinoflagellate

Cyanobacteria- dinoflagellate symbiotic relationship is known in the oligotrophic subtropical and tropical oceans. Dinoflagellate’ s requirement for fixed nitrogen as well as carbon is the driving force of this relationship. Immunolabeling- TEM suggested that some cyanobionts have a nitrogen-fixing capacity and probably temporally segregate their physiological processes to protect nitrogenase.