Preliminary report on the occurrence of lethal crustose (non-geniculate) coralline algae white band and white patch diseases in the coral reefs of Gulf of Kachchh, India

This is the first report on Crustose (non-geniculate) Coralline Algae (CCA) diseases in the Gulf of Kachchh, Western India. The observation of CCA diseases was conducted in the intertidal reefs of Narara coast during August to November 2021. Two CCA diseases were identified: CCA white band disease and CCA white patch disease. Five sites were selected along the Narara intertidal reef; each site covering 200 m² area with 5 belt transects. CCA colonies intercepted within the transects were identified based on their growth form, and lesions were counted and recorded. CCA were classified into six different growth forms: encrusting, fruticose, foliose, layered, lumpy, and warty. A total of 704 CCA colonies were encountered, of which 18±2.9 % (n = 127) were identified with white band disease and 6±1.9 % (n = 42) were identified with CCA white patch disease. The encrusting growth form was predominantly affected by both CCA white band and white patch disease. CCA white band disease causes tissue loss, typically resulting in the death of CCA, subsequently colonized by endophytic green algae; whereas algal colonization was absent in the white patches. CCA white band disease was observed with a high frequency of disease occurrence (FOC) at 80 %, and white patch disease at 44 %. The spatial distribution patterns of CCA white band disease (χ² = 30.03; p < 0.00001) and CCA white patch disease (χ² = 7.98; p < 0.005) significantly differed among the growth forms of coralline algae. Present account provides baseline information on CCA growth form density and CCA disease, which would be valuable for future investigations.