The elkhorn coral, Acropora palmata, has been a major reef-building coral in the Caribbean for the last 220,000 years. However, since the early 1970's, the dominance of this species within the reef system has declined dramatically (McClanahan & Muthiga, 1998). The decline of A. palmata can be attributed to two diseases: White Band and White Pox Disease. The following footage shows a patch of A. palmata covered with large lesions characteristic of White Pox (Patterson, et al., 2002). It has been demonstrated that this disease is caused by Serratia marcescens, a bacterial pathogen associated with human sewage (Patterson et al. 2002).

Credits
Cinematography: Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location: Bocas del Toro, Panama (2003)

McClanahan, T.R. and N.A. Muthiga (1998) Ecological shift in a remote coral atoll of Belize over 25 years. Environmental Conservation 25(2): 122-130.

Patterson, K., J. Porter, et al. (2002) The etiology of white pox, a lethal disease of the Caribbean elkhorn coral, Acropora palmata. Proceeding of the National Academy of Science 99 (13): 8725-8730.

By necessity all coral diseases have been described by their pathology (review by Richardson 1998). However, variation in pathologies show that the use of only visual clues for determining coral health and disease alone may be misleading (Kuntz et al. 2005). For example, this video shows two different coral species Acropora palmata and Siderastrea siderea, with similar pathologies. The small lesions covering the corals surface, reminiscent of white pox disease, are the result of fish feeding on tubeworms that live with the coral colony.

Credits
Cinematography: Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Neilan Kuntz
Location: Bocas del Toro, Panama (2003)

Richardson, L.L. (1998) Coral disease: What is really known? Trends in Ecology and Evolution 13: 438-443.

Kuntz, N.M., D.I. Kline, S.A. Sandin, F. L. Rohwer (2005) Energy and nutrient stressors cause different pathologies and mortality rates in three Caribbean coral species. Marine Ecological Progress Series 294: 173-180.

The necrosis of tissue is common in the pathology of coral diseases (Richardson, 1998). The pathology of banding diseases results in tissue necrosis as the disease progresses along the coral colony (Antonius, 1981). Several microbial agents, such as members of the Vibrio naceae (bacteria) are believed to be directly involved in tissue necrosis and diseases (Rosenberg and Ben-Haim, 2002). The following short clip shows a coral that is dying and has a small amount of live coral left. The remaining live tissue (distinguished by the brown pigmentation) is located along the outer edge of the coral. Close up shots show the interface between the live tissues and the exposed skeleton when the tissue have died and sloughed off.

Credits
Cinematography: Dr. Forest Rohwer
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location: Borneo, Malaysia (Sipadan) (2003)

Antonus, A. (1981) The “Band” diseases in coral reefs. Proceeding of the 4th International Coral Reef Symposium 2:7-14.

Richardson L.L. (1998) Coral disease: What is really known? Trends in Ecology and Evolution 13:438-443.

Rosenberg, E., Y. Ben-Haim (2002) Microbial diseases of corals and global warming. Environmental Microbiology 4 (6): 318-326.

Healthy corals are able to prevent macro-algal overgrowth. Corals diseases can act as a mechanism allowing benthic algae overgrowth due to the exposure of bare skeleton made available for recruitment (Diaz-Pulido & McCook, 2004). Progression of mortality on a coral colony often results in a clear demarcation between the apparently healthy tissues and recently exposed skeleton where the coral have been killed. The exposed skeleton is then rapidly colonized by macro-algae. Recruitment of algae is central to the process of reef degradation as hard coral coverage is replaced by benthic algae (Hughes 1994). This video clip shows the transition of a coral colony from healthy to diseased to final colonization by macroalgae.

Credits
Cinematography: Dr. Forest Rohwer
Edited by: Neilan Kuntz
Written by: Dr. Olga Pantos
Location: Borneo, Malaysia (Sipadan) (2003)

Diaz-Pulido, G., L.J. McCook (2004) Effects of live coral, epilithic algal communities and substrate type on algal recruitment. Coral Reefs 23: 225-233.
Hughes, T.P. (2004) Catastrophes, phase-shifts and large-scale degradation of a Caribbean coral reef. Science 265:1547-1551.

Coral bleaching occurs when the symbiotic algae, or zooxanthellae, are expelled from the coral animal tissue. A number of factors, both natural and anthropogenic, can cause bleaching ranging from elevated sea water temperature to bacterial and other infections (for review see Brown 1996). Coral bleaching is commonly used as in indicator of reef health. However, it can vary in frequency and severity within and between different species (Glynn 993). The observed differences in bleaching may be independent of coral species and a function of genetic variation in the associated zoooxanthallae (Symbodinium spp.) (Toller et al. 2001). Different closely related genetic groups or clades of zooxanthellae can be spatially separated within a single colony as well as being different between different colonies of the same species (Rowan et al. 1997). The following footage shows a coral colony that is bleached on the top portion of the coral. The reason for this pattern may be that this area of the colony contained a zooxanthellae clade more susceptible to bleaching those in the rest of the colony. Alternatively, it may be due to the fact that this part is exposed to a greater level of UV-radiation, which resulted in bleaching.

Credits
Cinematography: Neilan Kuntz
Edited by: Neilan Kuntz
Written by: Neilan Kuntz
Location: Bocas del Toro, Panama (2003)

Brown, B.E. (1996) Coral bleaching: causes and consequences. Coral Reefs 16:S129-S138.

Glynn, P.W. (1993) Coral reef bleaching ecological perspectives. Coral Reefs 12:1-17.

Rowan, R., N. Knowlton, A. Baker, J. Jara (1997) Landscape ecology of algal symbionts creates variation in episodes of coral bleaching. Nature 388: 265-269.

Toller, W.W., R. Rowan, N. Knowlton (2001) Repopulation of zooxanthellae in the Caribbean corals Montastraea annularis and Montastraea faveolata following experimental and disease-associated bleaching. Biological Bulletin (Woods Hole) 201: 360-373.