[Coral-List] Bleaching and Disease report - Flower Garden Banks NMS
emma.hickerson at noaa.gov
Fri Mar 31 11:33:39 EST 2006
This is an update on observations of the status of coral bleaching and
disease at the coral reefs of the East and West Flower Garden Banks,
northwestern Gulf of Mexico conducted the first week of March, 2006.
Coral bleaching was still present but much reduced compared to surveys
conducted in October and November 2005, but similar to results from
January 2006 surveys. A number of belt transects were conducted (same
locations as January 2006 surveys), 15 meters long by 1 meter wide, in
which every coral colony was counted and scored as to its bleaching
condition (totally bleached, partially bleached or unbleached).
Transects were established from known reference points (mooring buoy
anchor pins). The average number of coral colonies affected by bleaching
ranged from 4.0% (West FGB) and 5.7% (East FGB). As a reminder, this is
compared to an average of 42% in October, and 46% in November. January
(4.5%) and March (4.0%) observations were similar at the West FGB, and
continued recovery was documented at the East FGB; January (10.3%) and
March (4.0%). Of the species affected, Millepora alcicornis,
Stephanocoenia intersepta and Montastraea cavernosa had colonies that
were considered still "totally bleached" (0.5%), with most species
scored as "partially bleached". Video was taken along each transect but
has not yet been analyzed. Water temperature during the survey was 73
degrees F (22.8 degrees C).
Coral disease surveys were conducted along transects varying from 15m x
1m wide to 50m x 1m at both the East and West Flower Garden Banks. Coral
colonies exhibited white plague like symptoms on 3.33% at the West FGB,
and 8.34% at the East FGB. In localized areas at the East FGB, up to 20%
of the colonies were affected. In the previous bleaching surveys
(October and November) no disease was noted on the transects. White
plague symptoms were noted on Colpophyllia natans, Diploria strigosa,
Porites astreoides, Montastrea annularis, M. faveolata, and M. franksi.
Disease was also affecting the single known colony of Acropora palmata
on the East FGB. Last year, 2005, was the first year a widespread coral
disease event was documented at the Flower Garden Banks NMS, affecting
seven species. This also was a winter event. This event slowed as water
temperatures increased. This second event appears to be more severe.
Depths of surveys:
West FGB – approx. 70’-77’ (21.3-23.5m)
East FGB – approx. 60’ – 85’ (18.3-25.9m)
Diseased colonies were tagged to track the progress of the disease.
Additional surveys will be conducted in the coming weeks to monitor the
status bleaching and disease.
Observations provided by:
Emma Hickerson (FGBNMS)
Andy Bruckner (NOAA Fisheries)
Eric Borneman (Univ. of Houston)
Bob Jonas (George Mason Univ.)
Geoff Cook (George Mason Univ.)
Beth Zimmer (Florida Int’l Univ.)
Emma L. Hickerson
emma.hickerson at noaa.gov
Flower Garden Banks National Marine Sanctuary
1200 Briarcrest Drive, Ste. 4000
Bryan, TX 77802
PH: 979-846-5942, ext. 111
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