Keppel Island is completely bleached mainly due to the expansion of

Keppel Island, located in the southern Great Barrier Reef, has faced significant coral bleaching and mortality primarily due to thermal stress and biological outbreaks. While global warming is a primary driver of mass bleaching events [2], the Keppel Islands have specifically suffered from outbreaks of the Crown-of-Thorns Starfish (Acanthaster planci). These starfish are corallivores that prey on coral polyps, leading to widespread reef degradation and a 'bleached' appearance of the white calcium carbonate skeleton once the living tissue is consumed. The Great Barrier Reef Outlook reports highlight that such biological pressures, combined with extreme weather and rising sea temperatures, have caused the continued deterioration of reef health in this region. Unlike the other options provided, the expansion of starfish populations is a documented ecological threat that causes rapid and extensive loss of coral cover in the Keppel Bay area.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 4: Aquatic Ecosystem > 4.9.6. Ecological causes of coral bleaching > p. 52
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 4: BIODIVERSITY > coral Bleaching > p. 56