This list of threats to coral reefs is extensive and growing, and most of them are man made. The most recent is the acidification of the oceans from global warming, with its subsequent greenhouse gas absorption. The trend, if it continues, means real problem for growth of corals.

Threats To Coral Reefs

CLIMATE:
Reef Base

CORAL BLEACHING:
Coral Reef Ecology
Environmental Protection Agency
International Coral Reef Network
NOAA's "A Reef Manager's Guide To Coral Bleaching"
Oceans Alive
Odyssey Expeditions
Reef Base

CORAL FISH TRADE:
Reef Base
Global Trade and Consumer Choices: Coral Reef Crisis
National Public Radio: Coral Reefs in the Balance
Conservation International: Ravaging The Reefs

CORAL MINING:
Reef Base
International Coral Reef Information Network

DESTRUCTIVE FISHING PRACTICES:
Conservation Science Institute
Marine Conservation Biology Institute
Reef Base
The World Bank Group: Blast Fishing In Indonesia

DISEASES & BIOLOGICAL INFESTATIONS:
Diseases of Coral Reefs
Global Coral Reef Alliance: Mysterious New Diseases Devastate Coral Reefs
Reef Base Diseases
Reef Base Biological Infestations

EUTROPHICATION: 
Global Coral Reef Alliance: Eutrophication
Reef Base

EXOTIC SPECIES:
Reef Base
Community Environmental Research in the Pacific Islands: Crown of Thorns Starfish

HABITAT LOSS FROM DEVELOPMENT:
Threats to Coral Reefs: Human Development
World Resources Institute: Reefs threatened by human activity

MILITARY/NUCLEAR TESTING:
Reef Base

OVER HARVESTING:
Reef Base
World Resources Institute

PHYSICAL IMPACTS: Ship Groundings & Anchor, Pipeline and Cable Damage
Groundings on coral reefs and seagrass beds
Ship groundings smashing holes in Lauderdale coral reefs

POLLUTION:
Reef Base Industrial Pollution
Reef Base Marine Pollution

SEDIMENTATION:
Reef Base Manmade
Reef Base Natural
Threats to Coral Reefs

TOURISM:
The Negative Effects of Tourism on the Ecology of Jamacia
UNEP Tourism's Impact on Coral Reefs