Observations on naturally and artificially diseased tropical corals: A scanning electron microscope study

Area of Science:

• Marine biology
• Coral pathology
• Microbiology

Background:

• Coral diseases pose a significant threat to marine ecosystems.
• Black line disease is a specific coral affliction with observable characteristics.
• Understanding the microbial agents involved in coral diseases is crucial for conservation.

Purpose of the Study:

• To investigate the microbial composition of diseased corals using scanning electron microscopy (SEM).
• To differentiate between naturally occurring and artificially induced coral diseases.
• To identify the specific microorganisms responsible for the "black line disease" phenomenon.

Main Methods:

• Scanning electron microscopy (SEM) was employed to observe coral tissue.
• Naturally diseased coral samples were examined.
• Artificially induced disease models were created and analyzed.

Main Results:

• Both natural and artificial coral diseases exhibited a filamentous matrix containing cyanobacterial and Beggiatoa filaments.
• Spiral bacteria were frequently observed within this matrix.
• Artificially induced disease lacked cyanobacterial filaments and did not present as "black line disease."
• Beggiatoa filaments were consistently associated with diseased coral tissue.

Conclusions:

• Cyanobacteria appear to be a necessary component for the manifestation of "black line disease."
• Beggiatoa, a colorless, sulfide-oxidizing bacterium, is invariably linked to the observed coral disease.
• The findings provide insights into the etiology of coral black line disease, highlighting the roles of specific microbial players.