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Types
of Coral Disease and Their Identification
White Plague (WP)
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White
plague is one of the leading killers of massive and plating coral
species in the western Atlantic. It was first observed in Florida
in 1975. It re-emerged in 1995 and subsequently spread throughout
the region, with outbreaks reported from throughout the Caribbean
by 2001. It has become the most abundant and virulent coral disease
that now affects about half of all reef-building Caribbean coral
species. Plague can kill small corals in a few days, and in some
cases 500-600 year old star corals like this one may die in a few
weeks.
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Colony
of mountainous star coral (M. faveolata) with plague type
III.
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White
plague spreads readily from one coral to the next. In this photo,
a large colony of Dichocoenia stokesii (elliptical star coral)
has white plague as well as the small M. cavernosa (large-cup
star coral) in the lower right corner.
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corals affected by white plague, a sharp line separates healthy coral
tissue and bare coral skeleton, but there is no visible mat of organisms
at the disease front. |
Brain coral, Meandrina meandrites with white plague |
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Smooth brain coral, Diploria strigosa with white plague that
is spreading upwards from the colony base.
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Tissue
loss begins at the base or margin of a colony, or next to a previously
killed area, and quickly advances upward or outward.
In
many cases, corals located in sandy areas, especially at the perimeter
of a sloping sand channel, appear to be most prone to infection.
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Three
forms of white plague have been described: "plague
type I", which was reported in the 1970s and 1980s, "plague
type II", first reported in the mid 1990s, and "plague
type III, first reported in 2000. The disease signs of all forms
are similar, and there is some overlap of affected species.
The most obvious difference between the three forms of the disease
is the rate of spread and extent of tissue loss, which is greatest
in type III and least in type I.
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Mycetophyllia
alicea with
white plague
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The elliptical star coral is one species that was resistant to plague
type I, but is particularly susceptible to plague type II, with
outbreaks first reported from the Florida Keys in 1995.
A fine, but distinct, narrow band of bleached tissue may separate
normal, fully pigmented tissue from the white, exposed skeleton.
Tissue loss progresses at up to 2 cm per day.
In
the spring and summer of 2001, outbreaks of white plague among large
colonies of brain coral (C. natans) and star coral (M.
faveolata) were reported, with colonies over 1 meter in diameter
being killed in about a week. A bacterium has been identified as
a causal agent.
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White plague can be found on the following species of
coral:
Agaricia agaricites, Agaricia lamarcki, Colpophyllia
natans, Dendrogygra cylindricus, Dichocoenia
stokesii, Diploria
labyrinthiformis, Diploria strigosa,
Eusmilia
fastigiata, Isophyllia sinuosa,
Madracis decactis, Madracis mirabilis, Manicina
areolata, Meandrina
meandrites, Montastraea cavernosa, M.
annularis, M. faveolata,
M.
franksi, Mycetophyllia ferox, Mycetophyllia
lamarkiana, Porites astreoides, Porites
porites, Stephanoceonia intersepta,
Siderastrea siderea ,
Solenastrea bournoni.
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