Hunting the Cause of Stony Coral Tissue Loss. Looking at the Reefs with Scientific Vigor (3)

Stony Coral Tissue Loss Disease in Florida Is Associated With Disruption of Host–Zooxanthellae Physiology is a must read for those who seek more in-depth information 1

This blog is a continuance of previous blogs Death in Paradise and Fluorescent Photos to Measure Reef Viability. In this post I’m looking at two things: 1. Possible SCTL by infection and 2. Genetic engineering a replacement polyp to grow new SC surface tissue. Here is what can be done with fluorescent lighting.

Night photo of reef UB light(with false color brightening). Bright green fluorescent protein shows viable stony coral (SC) polyps. Magenta areas are viable algae. Blue areas are soft coral. Black are non viable surfaces.


Expose a fixed area to white light and with UB light. Photograph the area with the appropriate light filter. Similarily, expose variations of coral varieties, stages of disease, seasons, depth and other variables. Compare data among and between them.

In Figs. 1 and 2 look at the condition of the coral. They are suffering Stony Coral Tissue Loss Disease (SCTLD) with accumulation of dirt and covered with algae. This was typical of many areas of the reefs.

Fig. 1. Waiting for the night to start work
Fig. 2. Time to select the location and set up

In the previous blog , a fixed area was photographed with illumination to near ultraviolet (UB) light. Data of light, hue, chroma, luminance (CieLab. color space) was recorded. This can be seen in Fig. 3.

Fig. 3. Identification of fluorescence of specific locations or areas of a small sample showing multifocal Lytic Necrosis (LN) seen as black.

Identification of stages of SCTLD:

Fluorescence may facilitate a systematic description of SCTLD at the gross and microscopic levels. Photoshop CieLab, combined with white light examination may provide a better description of the disease stages.

Further research to be done to test infection-by-transference hypothesis:

A section of the coral with healthy and distressed polyps could be easily identified and biopsied as described by Woodly This identified area would look like the amber outlined section in Fig. 5.

Fig. 5. Use fluorophotography to select the area for biopsy and microscopic examination. This loss of Green Fluorescent Protein (GFP) may be the stage where the disruption of a host–symbiont physiology takes place. This may be the opportune stage to identify the DNA of a causative agent. Knowledge of this area could be helpful in future attempts at reengineering.

Method to rule out the infection-by-transference hypothesis:

  1. Isolation of healthy SC GFP polyps
    • Propagation of healthy polyps in sheet form
  2. Isolation of distressed polyps
  3. Application of distressed polyps to surface of healthy polyps
  4. Examination of time-lapsed photographs to determine if application causes distress and/or death of healthy polyps.
  5. Repeat
  6. Evaluate results
  7. Refine method and repeat

Method to detect the source of the infection hypothesis:

  • Select the healthy GFP polyps and their associated Zooxanthella 
  • Extract the DNA2
  • Select the BFP polyps
    • Extract the DNA2
  • Contrast and compare the two samples
  • Identify the point of difference.

Further research to be done:

  • Reengineering from knowledge of this area as shown above is a path not yet reported. Replacements for a variety of SC polyps might be engineered with the purpose of replacing the currently susceptible species.
  • Consider a new infective agent that is otherwise undescribed pathogen (prion?)

Reef Quality Assurance:

In order to determine the changes in large areas of a reef wall, fluorophotography may be applied for a quick scan. Large scale examination of a reef wall could be done using the photographic method described below. Fig 6. shows an area low in expectation for SC polyps. Fig. 7 shows the same area using UB lighting confirming that expectation.

Fig. 6. Determining the viability of a questionable location. White light illumination.
Fig. 7. UB illumination shows no green and no red. This is the best evidence of no viable SC polyps.

A wide angle view can show an area which fluoresces. This photograph shows an area of coral reef with heads illuminated with UB light that brightly reflect GFP. Estimates of the viability of an entire reef can be determined based on a percentage of an area which is bright.

This view of a reef wall shows the examples of a 3 X 4 M area using fluorophotography.


From the previous blog it was shown that coral fluoresence shows viable stony coral polyps. Reefs do vary in terms of variables mentioned above. Reef color value does indicate viability across all species. CIE Lab values do indicate the progress of SCTLD.

At least one method of reef biome intervention may be possible. Reef interventions can be measured at a large scale.

What measures should be initiated:

  • Pursue testing and rule out an infection hypothesis
  • Test genomic differentiations searching for causative agent
  • Systematize wide angle, macro and micro fluorophotography methods for quality assurance purposes
    • Use high resolution macro photographic camera
    • Use microscopic dissection and photography with UB lighting
    • Use variable blue to ultraviolet wavelength light sources in photography

Help is needed in this effort. If you have comments, questions or greater interests in the investigation and fight against SCTL disease please leave remarks and comments.


  1. SCTLD in Florida
  2. A genomic view of the reef-building coral Porites lutea and its microbial symbionts

#Fluorescent photography #SCTLD #stony coral #green fluorescing protein #GFP #BFP #DNA #Zooxanthella #polyps #coral #Caribbean #Lab


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