The actual reason behind burnt tips may be bacterial?

[Garf]

I had a dose of burnt tips when messing around with increasing alkalinity a couple of years ago. The standard "skeleton grows faster than the flesh" response was rediculous to me. Or "the coral grows so fast, the flesh is too thin" also pushed the realms of realism. It is well known that changes in pH, temp, nutrient concentrations, Alkalinity can change bacterial assemblages.

Although burnt tips are not directly indicated in the following reebuilders vid, I think he has put it all together. Certainly encompases my brief experience;

 

[Timfish]

I haven't had time to watch the whole video but here's some other links by scientists looking at issues with corals. Rohwer's bood is a very readable introduction to the roles of microbes in maintaing nhealthy reef ecosystems. Labile DOC (carbon dosing) is a major factor in causing pathogenic shifts in corals. Some of the microbes in question are normally found in coral microbiomes but excess DOC helps them shift to a pathogenic role. We also need to consider parasites that weaken corals and make them more susceptable to disease. One example is candidatus aquarickettsia rohweri which is an obligate parasite that steals it hosts phosphate reducing growth and can be transferred between corals.

"Coral Reefs in the Microbial Seas" This video compliments Rohwer's book of the same title (Paper back is ~$20, Kindle is ~$10), both deal with the conflicting roles of the different types of DOC in reef ecosystems. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems

Changing Seas - Mysterious Microbes

Microbial view of Coral Decline

Maintenance of Coral Reef Health (refferences at the end)

 

[djf91]

I don’t think burnt tips has ever been associated with growth. It’s more of an acute phenomenon where the tissue leaves the tips of branches and the bare skeleton is exposed. Happens over the course of hours.