[Coral-List] Porites Line Disease

[Charles Delbeek]

Julian Sprung wrote:
> Can someone post a link to some good photos of Porites Ulcerative White Spot disease? 
>
> I remember photographing colonies of Porites in the Solomon Islands with pale whitish spots on them, and after careful examination I found that this appearance was caused by small corallophila-like snails. I was just wondering how the appearance in this disease differs from what I saw.
>
> Sincerely,
>
> Julian
>   
I would echo Julian's comments. With over 30 years experience in keeping 
corals in captivity, one sees a lot of interesting markings on corals 
and areas of tissue loss, pigment loss etc etc. The advantage of keeping 
corals in captivity is that these changes can be observed daily from the 
moment they begin till they end. One can also observe the corals day and 
night. I wonder how many of the in situ observations and conclusions as 
to the causes of markings on corals are based on a few point in time 
observations? Many organisms that feed on corals such as gastropods, 
annelids and nudibranchs only appear at night, so unless you are doing 
night dives you would never see the "cause".

There are many factors that can cause corals to develop regions of 
tissue loss as we all know, and in some cases these can be attributed to 
predation. It is entirely possible that these "white spots" may be areas 
where predation has occurred at some point in time, and then the tissue 
has rapidly regrown the area but the zooxanthellae have not yet moved 
into this tissue, giving it the appearance of a "bleached" spot. I think 
some may be too eager in attributing some of these conditions to 
"disease" while overlooking other possible causes that may not be 
immediately obvious.

Sincerely,

-- 
J. Charles Delbeek M.Sc.
Aquarium Biologist III
Waikiki Aquarium
University of Hawaii
2777 Kalakaua Ave.
Honolulu, HI, 96815

(808) 923-9741 VOICE
(808) 923-1771 FAX