Coral reefs are in decline around the world. Threats to coral reefs come from both local and global sources.
- Physical damage or destruction from coastal development, dredging, quarrying, destructive fishing practices and gear, boat anchors and groundings, and recreational misuse (touching or removing corals).
- Pollution that originates on land but finds its way into coastal waters like sedimentation, nutrients (nitrogen and phosphorous) from agricultural and residential fertilizer, pathogens from inadequately treated sewage, toxic substances, pesticides, trash and micro-plastics from improper disposal and storm water runoff.
- Overfishing can alter food-web structure and cause cascading effects, such as reducing the numbers of grazing fish that keep corals clean of algal overgrowth.
- Coral harvesting for the aquarium trade, jewellery, and curios can lead to over-harvesting of specific species, destruction of reef habitat, and reduced biodiversity
- Natural phenomenon such as hurricanes
- Increased ocean temperatures and changing ocean chemistry i.e. ocean acidification are the greatest global threats to coral reef ecosystems. These threats are caused by warmer atmospheric temperatures and increasing levels of carbon dioxide in seawater.