A B C D E R S T W Y

A

Aspergillosis: Affects Sea Fans particularly. Affected sea fans show one or more irregularly-shaped patches or extensive loss of the purple tissue, with fine white filamentous material and sediment on the black axial skeleton that supports the tissue. Often, tissue adjacent to the patch is colored more deeply purple. Disintegration of the axial skeleton also occurs, leaving behind holes or complete loss of the sea fan blade structure. Sea fan tissue can also exhibit small dark purple spots and protuberant masses of purple tissue. Samples of diseased sea fans have contained fungal hyphae that are most closely related to the terrestrial fungal genus Aspergillus. Some species of Aspergillus are known pathogens of humans and other animals.

B

Bacterial Infection (BI): Mucus production is the main defense mechanism against outside intruders and is important to fight diseases. But sometimes the mucal slime, consisting mainly of glycopeptides, can lead to an unwanted cultivation of carbon and nitrogen feeding microorganisms, dominated by Desulvovibrio and Beggiatoa species in its final stages. In severe cases, when attacked by Phormidium corallyticum it is almost certainly will infect the coral tissue with Black Band Disease. Heavy microbial activity along with trapped sediments, quickly lowers the dissolved oxygen level of the closely surrounding waters, suffocating the delicate coral tissue underneath. Only strong wave action or currents can save the coral by mechanically ripping off the slimy coverage within days after formation. Black-Band Disease (BBD) : This disease is characterized by a black mat, a few millimeters to centimeters (about 1/4 inch to 2 inches) wide, on the surface of coral tissue, moving across the surface of the skeleton, leaving behind bare white skeleton. The remaining coral tissue appears normal in color, morphology, and behavior. The major component is Phormidium corallyticum, a photosynthesizing, gliding, filamentous cyanobacterium, in association with other cyanobacteria; e.g. Spirulina sp.; it proceeds progressively outward, thus affecting the entire colony. It can spread easily to other corals by means of wave action. Recent experiments indicate that coral tissue is killed by the lack of oxygen deep in the band next to the tissue and by exposure to hydrogen sulfide produced by these microorganisms. The organic compounds released by the dying coral cells apparently provide food for the microorganisms in the consortium. Black Aggressive Band (BAB): Although similar in appearance to BBD, the band material is somewhat thinner and appears gray rather than black allowing the tissue-deprived coral to shine through. Recent studies revealed another cyanobacterial genus (Spirulina) as one possible cause, but it is not excluded that even a spirochete Ballesteros sp. could be the main pathogenic agent. High phosphorous contents in affected tissues suggest that eutrophication may be one way to trigger of BAB, since its appearance is closely related to shallow and coastal areas. Black Overgrowing Cyanophyta (BOC): A number of other cyanophytic species like Calothrix crustacea, C.scopulorum, Hormothamnium solutum, Langbia confervoides, L.semiplena, Phormidium spongeliae, and Spirulina subtilissima sometimes simply overgrow the coral, starving the polyps. But in other cases they even actively penetrate and erode the coral skeleton, leading to the structural collapse of a branching coral. In some cases, under eutrophic conditions, BOC is not only more common but may even trigger White Band Disease. Bleaching: An important sign of disease in corals and some other reef organisms is "bleaching." Bleaching is the phenomenon in which the coloration disappears or becomes noticeably less intense, due to the loss of zooxanthellae and/or to the loss of photosynthetic pigments from these microalgae. As a result of the loss of the zooxanthellae, the white of the skeleton shows through the translucent coral tissue. Bleaching involves the change in the color of the tissue attached to the skeleton, but not the loss of actual coral tissue. Patterns of bleaching on a colony can vary, with only the upper surface or lower surface of the colony being affected, or bleached tissue can appear as a circular patch or in the shape of a ring or a wedge. The pattern of bleaching may give important clues as to the cause of bleaching. The nature and extent of bleaching varies between individuals within a species and among species at the same location. Coral bleaching has been attributed to exposure to high light levels, increased solar ultraviolet radiation, temperature or salinity extremes, high turbidity and sedimentation resulting in reduced light levels, and other factors. It appears to be a generalized stress response of the coral and some species are more susceptible to bleaching than others under the same conditions.

C

Coralline Lethal Orange Disease (CLOD): A relatively new disease and the bacteria that causes it is as yet unknown. Because of the important role played by coralline algae in reef building, this pathogen has the potential to greatly influence coral reef ecology and reef-building processes. It is characterized by Orange-yellow growths and/or a"band" of bright orange slimy material that spreads across the algal surface, leaving behind the bare skeletal carbonate remains of the coralline algae. When this material reaches the margin of the algal thallus, it forms upright filaments and globules, similar to those formed by terrestrial slime molds. The globules can be caught by waves and easily spread to nearby corallines. Coralline Lethal Disease (CLD): Very similar to CLOD but the bright orange band is not present. The pink algal tissue disappears along a thin white margin (1-2 millimeters wide) and filamentous algae grows over the bare coralline thallus. D Dark Spot/Dark Band Disease: This shows a characteristic dark band along the edge of tissue which is slowly dying back. In early stages it can appear as dark spots in the middle of normal tissue, which expand into a ring surrounding dead coral. Dark purple to gray or brown patches of discolored tissue, often circular in shape but also occurring in irregular shapes and patterns, are scattered on the surface of the colony (bright purple patches have also been seen on a bleaching colony) or appear adjacent to the sediment/algal margin of a colony. Sediment can accumulate in the centers of these patches, with bare skeleton occasionally seen when the sediment is brushed off. E Epizoism: By definition, this is an association in which animals live on others for substrate requirements. It's also not a disease in and of itself, per se. But the effects on coral are just as deadly. R Rapid Wasting Disease: Irregularly shaped, often large, patches of bare white skeleton appear on the surface of colonies of star coral and the brain coral Colpophyllia natans. The exposed skeletal surfaces are crumbly, often with the free edges of septa and pali missing or appearing to have eroded, with the result that the skeleton is depressed several millimeters to centimeters below the rest of the colony surface. The tissue margin can appear pale. The boundary between the skeleton and normal-appearing tissue is fairly sharp. In early intermittent observations, it appeared that tissue loss advanced across the surface of the colony at the rate of several centimeters (2-3 inches) per day; usually stopping when the patch was from 5 to 50 centimeters (2 to 20 inches) across on star coral, or continuing until the tissue was completely lost from the colony on brain coral. The cause has been attributed to both Parrotfish feeding and fungus. Red Band Disease (RBD): As the name indicates, the "band" is a soft microbial mat that is brick red or dark brown, not black, in color and easily dislodged from the surface of the coral tissue. This disease affects hard star, staghorn, and brain corals of the Caribbean and the Great Barrier Reef. The band in RBD appears to be composed of different cyanobacteria and microorganisms than those found in BBD and the microbial mat movement is different; the types of microbes present might be different depending on the coral host, but little is known about this. S Skeleton Eroding Band (SEB): A novel type of coral disease has been identified on Indo-Oacific reefs. It is caused by Halofolliculina corallasia, an eukyryotic protozoan, or more specifically, a colonial, heterotrich ciliate that damages not only the living tissue nut also the skeleton of the coral. The syndrome is found on a wide variety of massive and branching corals, and progresses similarly as in cases of BBD. The skeleton eroding band consists of masses of black loricae (black shaped housings) of the ciliate, with bifurcated, beige wings sticking out, resembling a bed of microscopic garden eels. Upon asexual reproduction, the loricae of the ciliate kill the colonized area by emitting chemicals that cause lysis of the coral tissue. The dotted appearance of the white zone behind the front distinguishes SEB from BBD. Sponge Disease: White-bordered dead holes in the sides of barrel, tube, and encrusting sponges. Samples have been taken for microbial culture, but identifications are still underway. This disease needs much study, but appears to still be in relatively early stages in most locations. W White Band Disease (WBD): Tissue peels or sloughs off the skeleton at a fairly uniform rate around the branch of the coral and progressing from the base of the branch towards the tip. On the staghorn coral (Acropora cervicornis), tissue loss may also occur in the middle of a branch. All that can be seen with the naked eye is the tissue peeling off the bare white skeleton with occasional small bits of tissue remaining on the exposed skeleton. The rate of tissue loss is several millimeters (1/8 to 1/4 inch) per day. The bare skeleton is eventually colonized by filamentous algae, but the band of bare white skeleton that remains visible can be 5 to 10 centimeters (2 to 3 inches) wide. No consistent population of microorganisms has been found at the margin of the tissue loss. White Plague (WPI and WPII): Tissue disappears from massive, encrusting, and branching species of corals at the rate of one or more centimeters (about 3/8 inch to 4 inches) per day, leaving behind bare white skeleton. The receding tissue appears as a sharp line at the skeletal interface. Early studies indicated that the disease could be spread from one colony to another suggesting that a pathogen was involved or related to physiological stress or other factors. The rapid loss of tissue is now called WP type II to distinguish it from the slower loss of tissue originally seen (WP type I). It appears to be highly infectious, possibly caused by a bacterium, and capable of spreading from one colony to another. White Pox: This disease is characterized by the appearance of irregularly-shaped patches of bare white skeleton. The patches can occur on the surface or undersides of branches. The tissue appears to peel off unevenly, but an even margin has also been found. The rate of tissue disappearance is unknown, but appears to be rapid, since the skeleton usually begins to be fouled by filamentous algae within a few days and the freshest patches can be several square inches (tens of square centimeters) in area but still have bare white skeleton. The cause is unknown. Y Yellow Blotch/Yellow Band Disease (YBD): It manifests itself as a broad yellow band moving across healthy coral tissue in a manner similar to the BBD. A band of decaying and sloughing off tissue is observed. However, the entire area denuded by the infection can retain the characteristic yellow color which can penetrate some millimeters into the skeleton. sclerectinians such as staghorn ( Acropora sp., Porites sp. ), honeycomb corals of the family Faviidae, plate corals ( Turbinaria sp. ), and even ecrusting species of the genus Montastrea.