[Coral-List] Observations of Thermal Bleaching and Irresponsible Development

[James M. Cervino]

Dear Coral Reef Scientists,

Observations of Coral Thermal Bleaching and Disease indices in Guana 
Key, Bahamas and a statement opposing any nutrient enriching golf 
course surrounding these sensitive reef systems.

This development will fertilize and increase the abundance of macro 
algae species within this habitat, thereby threatening this already 
thermally stressed coral reef ecosystem.   We are surprised that a 
team of marine scientists financially supported by the developer 
would claim that a golf course and dredge project will not harm the 
host tissues along with their symbioants on the surfaces of these 
diverse coral reefs 10 meters away from this proposed development 
site.  There are many publications out there that show how sediment 
loading can effect coral physiology (Peters, E. 1984.  A survey of 
cellular reactions to environmental stress and disease in Caribbean 
scleractinian corals. Helgol. Meeresunters. 37: 113-137.  I would be 
glad to supply these papers to the developers and their scientific 
advisors so that they can re-think their unsustainable development 
plans.   Many marine biologists may not have an understanding of the 
sensitive cellular mechanisms and physiology of symbiotic corals. 
Therefore, we would be more than glad to provide the advisory board 
of Discovery Land and Co. with this literature.

Observations

Coral Diversity was high and overall reef health was in good 
condition before this recent thermal expulsion event.  Temperatures 
were 84.5F at 60-70 feet. 86F at surface. 

North Side of the Island (furthest tip) adjacent to the proposed 
development project and golf course. Thermal Coral Reef Bleaching was 
in critical stages of expulsion of symbiotic algae of the following 
corals:

Method: 90 meter horizontal transect (1m/sq) at12 meters depth

1001individual counts of Montastraea sp. (not M. cavernosa) revealed 
959 in critical stages of bleaching of the 1001 counted.  This is the 
only species that I calculated exact numbers. The below species is 
based on approximate estimate:

Gorgonians Plexaurella nutans, Eunicea calculata  25-30% critical 
bleaching. Pseudopterogorgia sp. were unaffected.

One indices of YBD, however, it is important to note that the YB 
disease signs may be difficult to calculate due to the bleached 
tissue appearance. However, the one case was evident.

Acropora palmata on surface approximately 1-2 meters. All older 
colonies were dead (local reports claim WBD and storm damage). 
However, new recruits were evident with not White Pox or WBD lesions. 
Colonies of A cervicornis were not evident, only dead rubble was seen.

Montastraea cavernosa showed signs of brown spots lesions. On 25% of 
the colonies observed at all North and South dive locations.

50% Porites sp. were in critical stages of thermal bleaching which 
was surprising due this species ability to withstand high thermal 
stress.

Siderastrea siderea all showed signs of minor or early stages of DSD 
or past tissue necrosis with exposed skeleton. 

Stephanocoenia mechelinii were not seen bleaching. However, necrotic 
tissue was evident, causes wee unknown.  Non appeared to have DSD 
lesions on the tissue surface.

Diploria strigosa all colonies showed minor to middle stages of bleaching.

Meandrina meandrites  all appeared healthy. Very few were in direct sunlight.

Colpophyllia natans all colonies showed minor to middle stages of 
bleaching.  Parrot fish lesions were seen, however, small lesions 
approximately 1-2 cm was the average size.  Not one observation of 
10-20 inch lesions were evident within a 24 hr time period as seen 
during the PFWSB/RWD debate during 1996-97.  All of the lesions seen 
during this time showed no necrotic tissue border after the biting.

Fungiida (Leptoseris cacullata) all appeared healthy.

Agaricia lamarcki all that were in direct light appeared mildly 
bleached. In the more dark areas, all appeared healthy.

Agaricia tenuifolia were all in mid to late stages of bleaching. 
Symbiotic algae were seen in mucus streams above the coralite.

Madracis Formosa were seen in mild stages of bleaching.

Oculina tenella were in mild stages of bleaching.

Sea-fans all appeared healthy, outside of 2 cases of Sea fan Disease 
that were effecting the older colonies. All healthy Seaman's were 
juveniles  between 5-10 cm long. 

All reef fish were abundant and diversity seemed to be high.

Macro Algae and Ecology of this habitat.
As many of us coral biologists understand, coral reefs are known to 
be the most nutrient sensitive ecosystems. Coral reefs can become 
"eutrophic", that is, overgrown by weedy algae, at nutrient levels 
that are so low that they would indicate nutrient starvation in any 
other ecosystem  (P. Bell,1992, Eutrophication and coral reefs: some 
examples in the Great Barrier Reef lagoon, Water Research, 26: 
553-568; B. Lapointe, & M. Clark, 1992, Nutrient inputs from the 
watershed and coastal eutrophication in the Florida Keys, Estuaries, 
15: 465-476; B. Lapointe, in press, Eutrophication thresholds for 
macroalgal overgrowth of coral reefs, in K. Thacker (Ed.) Protecting 
Jamaica's Coral Reefs: Water quality issues).  Therefore, an 
immediate stop work order on the proposed development location should 
be established as a result of human-caused nutrient additions from 
The Discovery Corp. to these coastal waters surrounding Guana Key. 
This is needed to prevent the corals from being overgrown and killed 
by weedy algae.  This golf course will be a point source and will 
create dangerously high levels of nutrients. Any nutrient drainage 
into this area will cause the reefs to deteriorate further. This 
includes nutrients from development projects involving dredging, 
which will lead to sediment loading on the surfaces of corals on the 
north and south side of Guana Key, as well as from construction of 
the golf course and excess sewage that is usually accompanied by such 
projects. The Discovery & Co. EIA plans are to dredge up a portion of 
the 1 mile island, dump the sediment onto the surrounding reef and 
add soil fill combined with quartz sand for this golf course.  This 
limestone substrate will act as a permeable filter for the nutrients 
to leach out into the reef thereby feeding the invasive species.

The dominant macro algae were species indicative of moderate or low 
nutrients, primarily Dictyota pinnatifida, Laurencia poiteaui, 
Halimeda sp., Udotea sp,. and Penicillus sp. These were not at 
invasive levels at this point in time. However,  All cyanobacteria 
spp.  (blue-green algae) Lyngbya penicilliformis were in low 
abundance. Nutrient analysis is need at this point in time to 
establish a base line of the chemical signatures surrounding this 
reef around the proposed development site and  surrounding Guana Key. 
Only stressed corals were in competition with Lyngbya, and all dead 
corals were overgrown with mixed algal tufts.  High densities of 
cyanbacteria are indicative of excessive pollution, in particular of 
phosphorus, and are common near sewage inputs. On shallow and deeper 
sandy areas the algae were more typical of lower nutrients, primarily 
Halimeda, Udotea, and Penicillus species.  It is important to note 
that acceptable water quality standards for coral reefs has been 
established by Lapointe and Bell, and show that over fertilization by 
nutrients, not the lack of fishes and sea urchins, are the major 
reason for the almost complete replacement of corals with weedy algae 
(Goreau et al. http://globalcoral.org/).  All areas show healthy 
abundance of seagrasses with low macro-algal overgrowth.

Recent research in the Caribbean and in the Great Barrier Reef of 
Australia has established the critical levels of nitrogen and 
phosphorous which must not be exceeded if reefs are to remain healthy 
without being overgrown by weedy algae (Lapointe et al., 1992, 1993; 
Bell, 1992). These concentrations are:

1.0 micromoles per litre of nitrogen as nitrate and ammonia
0.1 micromoles per litre of phosphorous as ortho-phosphate and organophosphate.
These values are in the molecular concentration units used by 
chemists and oceanographers. In the weight units more often used in 
the wastewater literature these translate into:
Nitrogen: 0.014 ppm N or 0.040 ppm NO3
Phosphorous 0.003 ppm P or 0.007 ppm PO4

This 1-2mm layer of skin (epidermis) living on the surfaces of corals 
is subjected to extreme conditions and are living at their critical 
maximum stress threshold levels during this current time.  Given the 
state of the worlds reefs is it wise for the Bahamian Govt. and an 
American Company to allow such an irresponsible project to take place 
? Thermal coral-bleaching will intensify along with the rise in heat 
trapping gasses over this next century. Since we cannot convince and 
control the current Cheney/Bush administration to control atmospheric 
carbon dioxide (heat trapping gasses partly responsible for global 
warming) would it not be wise to at least address localized threats 
to coral reefs ?  My research assistant and I would like to thank the 
local environmental group on Guana Key for their efforts in 
preserving and respecting this coral reef ecosystem.

-- 
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Dr. James M. Cervino, MS, Ph.D.
Marine Pathology
Department of Biological & Health Sciences
Pace University New York NYC
Phone: (917) 620-5287
Web site: http://www.globalcoral.org
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