Black-band disease dynamics: Prevalence, incidence, and acclimatization to light

作者：Muller E M^*; van Woesik R

来源：Journal of Experimental Marine Biology and Ecology, 2011, 397(1): 52-57.

DOI：10.1016/j.jembe.2010.11.002

• Black-band disease
• Coral disease
• Diploria strigosa
• High water temperature
• Irradiance
• Photoinhibition

Black-band disease (BBD) is a temperature- and light-dependent syndrome typically found on shallow-dwelling corals. The bacterial consortium that creates BBD contains a photosynthetic cyanobacterium, which is particularly sensitive to light. High light causes the BBD cyanobacteria to self-shade, which encourages the formation of the anoxic microenvironment essential for the BBD consortium. From May to September 2009, a shallow-reef area was monitored to quantify the epizootiology of BBD on the brain coral Diploria strigosa. The prevalence and incidence of BBD were recorded approximately every two weeks. To test the hypothesis that reduced light would increase the rate of disease progression by reducing photoinhibition in the BBD cyanobacteria, shade structures, made out of plastic sheeting on a polyvinyl chloride (PVC) frame, were installed above D. strigosa colonies with BBD. The shade material reduced photosynthetically available radiation (PAR) by >80%. The progression of BBD on shaded colonies was compared with cage control and control colonies. A pulse-amplitude-modulation fluorometer was used to measure the amount of PAR and maximum excitation pressure (Q,) on each colony after two weeks of treatment. Linear progression rates and the band width of BBD were measured weekly and treatments were compared through time. During the summer months, the prevalence of BBD showed a positive, exponential relationship with water temperature, whereas the incidence of BBD displayed a positive linear relationship with the rate of change of water temperature. PAR on, and the Q, of, shaded corals was significantly lower than the two control treatments: however, Q, values did not indicate excessive photochemical pressure on the coral host. The progression rates of BBD and the black-band width on shaded colonies significantly increased after one week of shading, whereas the control treatments did not change. During the second week of manipulation, however, black-band width and progression rates were similar to values prior to manipulation. These results suggest that, even under low-light conditions, a compact and dense 'black' band is essential for the persistence of the BBD consortium.

• 出版日期2011-1-31