Characterization of coral associated ciliates and their interactions with disease lesion progression of Indian Scleractinian corals

• Published in: Microbial pathogenesis Vol. 149; p. 104472
• Main Authors: Ravindran, Chinnarajan, Bhagwat, Phartade Vilas, Silveira, Kris Anthony, Shivaramu, Mamatha S., lele, Upendra P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2020
• Subjects: Ciliates; Corals; Disease; Infections; Pathogens; Pathogens; Ciliates; Infections; Corals; Disease
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2020.104472

Ciliates associated with advanced diseased lesions of Acropora sp. and Porites sp. in the field were isolated and characterised using microscopic and molecular analysis. The identified dominant coral-associated ciliates as Holosticha sp. and Cohnilembusverminus was propagated in vitro and taken for further study. Ciliates high cell numbers with substrate containing bacteria-free mucus confirms the feeding preference for nutrients in mucus instead of bacteria. Therefore, fatty acid composition of the coral mucus was analysed and noted for the different composition levels of SAFA, MUFA and PUFA in both the genera. This suggests the possible feed specific interactions of ciliates with coral mucus and tissues. Conversely, Holosticha sp. was observed for invading the host cells for its voracious ingestion of Symbiodiniaceae cells and tissues. Moreover, the aquarium based investigation revealed that the ciliates migrate to the injured and early disease signs of corals enhancing the tissue loss and disease lesion progression. Thus, our results indicate that the ciliates interact with the immunocompromised disease corals and play a major role in progression of disease lesions leading to rapid coral mortality. •Disease lesion associated ciliates were isolated, identified and characterized.•Ciliates feed specific interactions with diseased corals were described.•Fatty acid composition of coral mucus of Porites and Acropora was analysed.•Ciliates were observed for their ingestion of zooxanthellae.•Ciliates enhanced the disease lesion progression in diseased and injured corals.