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Coral Diseases & Syndromes
- Though coral diseases have presumably existed for as
long as reefs, they have only been recognized as such
within the past 30 years. However, over the past decade a
number of "new" diseases and syndromes (i.e., potential
disease states) have been documented in numerous coral
reef communities. Other diseases and syndromes appear to
be spreading or intensifying.
- As increases in the incidence, prevalence and
intensity of disease is often related to changing
environmental conditions and increases in stress, the
concern is that the wave of diseases and syndromes now
afflicting coral may be an additional sign of increasing
and significant degradation and alteration of coastal
environments.
- aspergillosis - The likely cause of
sporadic sea fan mortality events thoughout the
Caribbean since about 1982; Recurrence of sea fan mass
mortalities began again in 1995 on reefs in the
Caribbean, the Bahamas, and the Florida Keys
- black band disease - 1st documented in the
early 1970's and found worldwide, tends to be found on
coral stressed by nutrients and toxic chemicals or
increased temperatures
- bleaching - Documented since the turn of
the century but the huge bleaching events in coral
reefs around the world since the 1900s are
unprecedented
- coralline lethal disease - 1st documented
in 1996 in the Caribbean with subsequent observations
in the Indian Ocean and off the Philippines
- coralline lethal orange disease - 1st
documented in 1993 in South Pacific reefs where it
encompassed a range of at least 6000 sq. km;
condition is currently spreading
- dark spot disease - Though noted for many
years there has been a noticeable increase in its
occurence; now widespread throughout the Caribbean and
Florida Keys
- irregular coloration - Just recently
documented in the Caribbean; little is known of the
significance, if any, of this syndrome
- rapid wasting syndrome - 1st documented in
1996 and found in the Florida Keys and the Caribbean;
associated with parrotfish predation but questions
remain as to the involvement of fungi
- red band disease - 1st described in 1992
and found in the southern Florida Keys, the Bahamas
and the Caribbean
- sponge wasting disease - 1st documented
within the last two years; the erosion of tissue
associated with this disease affects sponges in the
Caribbean
- white band disease - type I - 1st
documented in the mid-1970s; continues to kill coral
in the Caribbean, the Philippines, the Red Sea,
and the Great Barrier Reef
- white band disease - type II - 1st
documented in the early 1990s in the Bahamas
- white plague disease - type I - 1st
documented in 1977 and found worldwide
- white plague disease - type II - 1st
documented in 1995 in the Florida Keys; of great
concern as it causes extremely rapid tissue loss and
death in many coral species
- white pox - 1st documented in 1996 in the
Florida Keys where it has now reached epidemic
proportions; it has recently been noted in the
Bahamas
- yellow band/ blotch disease - 1st
documented in the Florida Keys in 1994; it severely
effects massive 200 to 300 hundred year-old star coral
colonies throughout the Caribbean
- yellow band disease - 1st documented in
1997 in various coral species in the Arabian Gulf
- A disease is any impairment that interferes with the
performance of an organism's normal function, including
its ability to respond to environmental stress.
- Disease my be caused by pathogens such as viruses,
fungi, or bacteria (i.e., infectious disease) or by such
factors as inadequate nutrition, genetic mutations, or
unfavorable environmental conditions (i.e.,
non-infectious disease). Stress, such as pollution or
unfavorable temperatures, can overwhelm or weaken an
organism's defense mechanisms thereby increasing its
susceptibility to opportunistic disease agents, or it may
cause a breakdown in an organism's key metabollic
processes. In addition, changes in environmental
conditions -- such as warmer temperatures -- can promote
an increase in pathogens thereby augmenting their
potential to infect a susceptible host.
- Little is currently known about either the primary or
secondary causes of most coral diseases and syndromes.
This is in large part due to their very recent emergence
and to the complex interactions involving the coral
community, environmental processes and stresses, and
pathogens.
- However, coral communities thoughout their range are
being stressed by various human-related activities such
as increased levels of UV radiation, exposure to toxic
chemicals and oil, increased nutrients from sewage
discharge, and by siltation and water turbidity from
dredging or sediment run-off due to coastal development
and deforestation. As well, many scientists suspect that
climate change may be causing the increases in water
temperature that have been correlated with global
episodes of coral "bleaching". Other factors involved in
the decline of coral communities include overfishing,
fisheries involving dynamite or cyanide, and coral
mining.
- Perhaps as much as 10% of the world's coral reefs
have been degraded beyond recovery while many more are in
serious decline. Pressures on coral systems are likely to
increase concommittant with rapidly expanding human
population growth along coastal environments.
- Emerging diseases and syndromes in coral communites
are examples of a growing number of such events and
conditions afflicting both aquatic and terrestrial fauna
and flora. Indeed, emerging diseases may be an important
signal that a critical threshold of ecological change has
been reached.
Glynn, P.W. 1996. Coral reef bleaching: facts,
hypotheses and implications. Global Change Biology
495-509
Hayes, R.L. and Goreau, N. I. 1998. The significance of
emerging diseases in the tropical coral reef ecosystem. Revista de Biologia Tropical 46: 173-185.
Richardson, L. 1998. Coral diseases: What is really
known? Trends in Ecology and Evolution 13(II):
438-443.
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