Diseases such as blackband and whiteband disease are caused by excessive warming of waters

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Two diseases frequently observed on corals are blackband and whiteband disease.

These diseases actually kill coral tissue while advancing in a band around the

coral and leaving the white coral skeleton behind. When blackband disease

kills part of a colony, the skeleton is then available to be colonized by other

coral species recruits. In fact, some scientists suggest that blackband disease

may actually help maintain coral diversity because it is most prevalent in coral

species that form large colonies. Studies have shown, however, that there were

no coral recruits among corals infected by blackband disease after 25 months.

It is believed that whiteband disease is caused by a bacterial pathogen not

yet known. It affects corals much as blackband disease , leaving behind a white,

lifeless coral skeleton. Unlike blackband disease , scientists do not see whiteband

disease as being beneficial to reefs. Scientists have shown that whiteband disease

destroys the reef structure because algae, invertebrates, gastropods and boring

sponges colonize the dead coral skeleton. This colonization works to weaken the coral

skeleton,making it more susceptible to breakage during storms.