White-band disease in Caribbean coral reef communities is best described as which type of ecological effect?

• A. A local, isolated effect affecting only coral
• B. A cascade event that shifts the entire makeup of the community
• C. A short-term fluctuation with no long-term effects
• D. A pathogen that increases species richness

Answer: (D)

Disturbances like disease can trigger cascades that ripple through an ecosystem, changing not just the target species but the entire community and how it functions. White-band disease kills corals rapidly, removing the physical structure and habitat that many other organisms rely on. As corals decline, reef complexity drops, leading to shifts in which species thrive—for example, more algae may take over, and fish and invertebrate communities that depended on live coral can decline. This chain of effects shows how a disease can cascade through trophic relationships and habitat structure, altering the overall makeup of the reef community over the long term. It isn’t simply a localized, short-term hit to one species, nor is it a pathogen that increases species richness.