[Coral-List] coral bleaching observations in St. John, USVI

Jeff Miller jeffmiller at islands.vi
Fri Oct 3 16:13:17 EDT 2003

Greetings Coral-listers,
The following is a summary of bleaching conditions from around Virgin 
Islands National Park, in St. John, USVI.  These observations are based 
on 18 dives at three reefs since Sept. 22.  Depths range from 6-17 meters.

Water temperature at Yawzi Reef (14 meters deep) on September 4, was 
28.5° C and on October 2, was 29.8° C  (data by Ryan Industries Thermistor).

The fire coral Millepora alcicornis is exhibiting more bleaching than 
other species.  It varies from pale to white.  Most colonies of this 
species are bleached.

About one third of the Agaricia agaricites colonies are pale or white.

Approximately one fourth of the Siderastrea siderea colonies are either 
pale or purple.

Montastraea annularis (complex), Porites porites, and P. astreoides are 
occasionally pale, sometimes totally bleached. However these conditions 
are not prevalent, and looking over a reef, many more colonies are 
"normal" in color than are discolored.

A few colonies of other species (Diploria labyrinthiformis, Colpophyllia 
natans, Leptoseris cuculata are very infrequently observed pale or bleached.

Interestingly, we've observed that the majority of colonies of L. 
cuculata have new growth at the edges.  We have observed this condition 
over the past six months.

Also, monthly disease monitoring (for white plague) conducted in 
September (one of the warmest water months) revealed the least amount of 
plague-induced coral mortality from this disease since monthly 
monitoring began (in December 1997).

Please feel free to contact me with any questions about these observations.

Jeff Miller

Fisheries Biologist
Virgin Islands National Park

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