Top Threats to the Great Barrier Reef: Climate, Fishing, and Runoff

The Great Barrier Reef (GBR), Earth's largest coral system, faces escalating threats:

1. Climate Change: #1 threat. Marine heatwaves cause mass bleaching (2016, 2017, 2020, 2022). Ocean acidification slows calcification. Cyclones increase in intensity.
2. Water Quality Decline: Agricultural runoff (sediments, nutrients, pesticides) from Queensland farms smothers corals, fuels crown-of-thorns starfish outbreaks, promotes algal overgrowth.
3. Crown-of-Thorns Starfish (COTS): Population explosions devour coral; linked to nutrient runoff reducing larval predators.
4. Coastal Development: Port expansions, dredging, urbanization increase turbidity and pollution.
5. Fishing Pressure: Overfishing disrupts food webs; illegal fishing; bycatch of protected species.
6. Shipping: Groundings, oil/chemical spills, noise, anchor damage.
7. Plastic Pollution: Ingestion, entanglement, toxin vectors.

Management: Reef 2050 Plan, water quality targets, COTS control, marine park zoning, climate action advocacy. Survival requires limiting warming to 1.5°C.