Observations of brown band disease in the Gulf of Mannar, India

Abstract

The abundance and frequency of coral diseases have increased significantly during recent decades. The Gulf of Mannar in India has well-established coral reefs that have been affected by various climatic and non-climatic issues. Coral diseases, predominantly growth anomalies and white syndromes, have been reported on these reefs, but here we report the first observations of the ciliate disease brown band (BrB) on reefs of the Gulf of Mannar. Colonies with BrB lesions were found at 2 of the 21 islands surveyed, namely Poovarasanpatti and Puluvinichalli. Microscopic analysis of coral lesions confirmed the presence of zooxanthellae within ciliates indicating active feeding of coral tissues. The overall prevalence of BrB disease was 0.8% in Poovarasanpatti and 0.3% in Puluvinichalli. We only found Porites and Platygyra colonies infected with BrB ciliates even though Acropora, which is usually targeted by BrB, was the most abundant coral in our transects. This study extends the geographic range of BrB to the Gulf of Mannar and the host range to include Platygyra spp.