Human+impact

Coral reefs provide important ecosystem goods and services, such as fisheries and tourism. They also have great aesthetic and cultural value.

Until recently, the direct and indirect effects of overfishing and pollution from agriculture and land development have been the most significant causes of the accelerating degradation of coral reefs in many places, particularly the Caribbean. These human impacts have caused ecological shifts away from the original dominance by corals to a preponderance of fleshy seaweed or other weedy non-coral species. Run off of pollutants from agriculture including the fertilisers and nutrients used by farmers has had a mjor impact. The building of high density housing and the reshaping of foreshores and river frontages has also meant damage to the reefs through fresh water and polluted storm waters washing into the reefs.

More recently, the impacts of **global climate change**, including coral bleaching and the emergence of disease have made some worrying changes to the reef structures. Even otherwise lightly impacted reefs, such as the northern and outer Great Barrier Reef, are increasingly vulnerable to climate change. Coral reefs are in serious decline globally; an estimated 30% are already severely damaged, and close to 60% may be lost by 2030.

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Issues to consider carefully:

Collection of reef fish and coral for aquarium collectors often includes the use of cyanide which stuns the fish so they are easier to catch. This often leads to the destruction on the reef.
 * Fishing** - **both for food, and for the aquarium trade**.

The reef fishing industry often uses dynamite which damages and often destroys the reefs. Overfishing disturbs the balance as the number of fish being removed is greater than the numbers breeding to restock. This will mean that over time, that food stocks will be under stress for both fish and people, and will change the nature of the fish stocks as preditor fish are removed from the food chain.

There is often lack of control and planning of tourist developments. Wastes from the resorts often end up in the reefs increasing the nutrients, disturbing the delicate balance.
 * Tourism**

Tour boats and people walking on the reef can crack and break coral, and stir up sediments which also increases the risks to the coral.

As tourist developments are built along reefs, and more people choose to live permanently closer to the coast, the potential for damage increases. In poorer countries, many people build over the reefs as their home islands are destabilised by the rise in ocean levels. In richer countries, there are high rise developments, canals are made so that more waterfront is created, and the coastline is permanently changes.
 * Coastal Development**

Farming often results in landclearing and logging. This causes land erosion and the soils wash into the river system. This will often end up in the sea. If they are near coral reefs, then this adds to the nutrients and sediments that destabilise the reef ecosystem.
 * Farming**

Mining for oil, sand and other minerals often happens on or near the reefs. This is a major source of damage to the reefs, especially where there is the potential for oil or other products to be let into the ecosystem through spills.
 * Mining**

Large freight carriers and tourist boats can do great damage to the reefs, underestimating the depth of the water, and shattering the coral, or allowing pollutants, such as oil spills and sewerage into the water.
 * Shipping**