BICD 2005

An Introduction to Coral Disease

Bay Islands College of Diving, Utila

BICD 2005

Contents• History of coral disease • Black-band disease • White-band disease • White plague • Yellow-blotch disease

BICD 2005

History of Coral Disease• Western Atlantic has undergone dramatic change recently; human

activity, natural disturbances & deterioration of water quality

• Hurricanes, diseases & predators in 1970’s & 1980’s transformed Elkhorn & Staghorn thickets into fields of coral rubble & skeletons

• From 1983 water-borne disease wiped out 90% of Long-spined Urchin, which previously controlled algae growth

• Storms have increased sedimentation & nutrient run-off from land, rivers & sewage

• Number of coral diseases escalated during 1990’s & now infect most common reef building corals in the Caribbean

BICD 2005

Possible Causes of Coral Disease

• Infectious pathogens – bacteria & fungi

• Human & natural stresses

• Elevated sea water temperatures

• Increased ultraviolet radiation

• Increased sedimentation, nutrients & pollutants – may increase pathogens or decrease a coral’s defense & immune mechanisms

• Still an unknown quantity but through reef monitoring programmes & improved lab investigations, coral disease are being better understood

BICD 2005

Black-Band Disease

• Crescent-shaped or circular band of blackish material separating living, coloured tissue from white exposed skeleton

• Infection starts at fringe of colony and advances 2mm-2cm per day

• Corals are more susceptible during calm, clear waters in summer

• Affects reef-building and plating corals, especially Boulder Star Coral & Symmetrical Brain Coral

BICD 2005

White-Band Disease• This leaves a distinctive white band

of limestone skeleton next to dying tissue

• Advances from base of branching corals (Elkhorn & Staghorn) towards the tips

• Tissue peels away from skeleton at a rate of 5mm per day

• The exposed skeleton is then colonized by algae within a few days

BICD 2005

White Plague• Similar in appearance to WBD – a

sharp line separates healthy tissue from skeleton

• Tissue loss begins at the base of the colony or next to previously diseased area

• Disease advances at a rate of 2cm per day

• Affects reef-building and plating corals, primarily Pillar Coral, Star & Starlet Corals, Cactus Corals & Boulder Brain Corals

BICD 2005

Yellow-Blotch Disease

• Pale yellow, circular blotch of tissue in middle of colony or as a narrow band at the edge. Infected areas are surrounded by normal, dark green or brown tissue

• Advances at a rate of 1cm per month which is relatively slow

• Highly contagious. Jumps on you if you do not pay close attention. Be aware!!

• It is a bacterial infection