Yellow-Band Diseases

Yellow-band diseases manifest in different ways in a variety of regions in the world. Originally described in the Caribbean in the 1970s, it was observed in the Florida Keys in 1994 and identified as "ring bleaching" eventually it was observed in the Arabian Sea and the Indo-Pacific. Yellow-band diseases affect faviids primarily in the Caribbean, Porites and Acropora spp. in the Persian Gulf, and faviids and fungids in the Indo-Pacific. Because YBD had been identified with different names, the various syndromes have been renamed to reduce confusion: Caribbean yellow-band disease, Indo-Pacific yellow-band disease, and Arabian yellow-band disease. Arabian yellow-band disease manifests as a bright yellow band that migrates across coral in a linear to annular pattern producing a margin of decaying tissue adjacent to healthy tissue and leaving behind dead skeleton. It impacts Acropora and Porites spp. primarily. Caribbean yellow-band disease was first reported as "ring bleaching" and was later called yellow-band disease and yellow-blotch disease; it manifests as a yellow band on the margin of a colony or a yellow blotch within the colony surface. Multiple lesions may appear on a coral and these often coalesce over the duration of the infection. It primarily affects Montastraea spp. and isolated cases in other faviid corals. CYBD advances slowly (1-2 cm/month) but infections can last 6-7 years or until the coral dies. Nutrients have been linked to increased tissue loss. Pacific yellow-band disease exhibits gross signs similar to those observed in CYBD; it affects Diploastrea, Fungia, and Herpolitha spp. It first appears as a pale yellow blotch at the colony perimeter or as a narrow band at the colony margin. Four Vibrio species have been implicated in PYBD, which is accompanied by zooxanthellae lysis without expulsion.