Outbreaks of Acropora white syndrome and Terpios sponge overgrowth combined with coral mortality in Palk Bay, southeast coast of India.

Acropora white syndrome (AWS) and Terpios sponge overgrowth (TSO) are serious threats to coral communities in various regions; however, information on these 2 lesions in the Indian Ocean is much more limited than in the Indo-Pacific. The present study revealed the impact of these lesions on the Palk Bay reef, India, and covered an area of 7 km2. In total, 1930 colonies were permanently monitored to assess incidences of AWS and TSO and consequent mortality for a period of 1 yr. TSO affected 5 coral genera and caused 20.7% mortality; overall prevalence increased from 1.3% (n = 25) to 25.5% (n = 492). In contrast, AWS only affected Acropora colonies and caused a mortality of 8%; overall prevalence increased from 0.9% (n = 17) to 12.9% (n = 249). Year-round monitoring revealed an increasing trend of both AWS and TSO, followed by temperature rise. These results add to the known geographic distribution of these coral diseases and reveal the impacts of AWS and TSO on coral reefs in the Indian Ocean.