Coral reefs are degraded by an accumulation of stress from human activities. Overfishing, pollution and coastal development are high on the list of factors in chronic stress. Some coral reefs are covered with sand and sediments. Others are dredged or blasted for their limestone or to improve access and safety of navigation. In addition to this, the overall long-term changes (higher sea temperatures and CO2 levels), storms, earthquakes and volcanic eruptions also affect coral reefs.
Increasing demand for fish has led to overfishing of reef species. Overfishing of certain species can easily affect the ecological balance and biodiversity of the reef. For example, overfishing of herbivorous fish can lead to high levels of algal growth that can quickly suffocate corals.
DESTRUCTIVE FISHING METHODS
Dynamite fishing and cyanide makes the fish easier to catch. These practices do not target species, they destroy all where they are applied. Damage to the coral reef habitat affects the entire reef ecosystem, and thus an immediate impact on the livelihood of the fishermen concerned.
Tourism generates large amounts of money for the host country. When unregulated tourism pressures can cause damage to the surrounding environment neglecting divers, boat anchors misplaced Hotels discharging untreated wastewater (water polluting, creating sedimentation, while encouraging growth algae that competes with corals).
Coral reefs need water low in minerals to develop. Pollution from land-based human activities, when carried by rivers into coastal waters can damage coral reefs.
It is estimated that nearly 2 million people worldwide have a marine aquarium. The vast majority of marine aquariums are provided in the species caught in the wild, so wild. Threats of this trade include the use of cyanide to the collection, over-target organisms and the high levels of mortality associated with maintenance practices and summary shipment.
Coral bleaching occurs when the symbiosis between corals and their symbiotic zooxanthellae (algae) stops, resulting in the loss of these microalgae and rapid bleaching of coral host (hence the term “bleaching”). This is a stress response by the host which coral can be caused by various factors, but the most common and most serious cases are caused by an increase of the surface temperature.
If the ocean surface temperatures continue to rise, the frequency and severity of coral bleaching will also increase, possibly affecting the ability of coral reefs, as we have known them, adapt and provide most services we ask their.
This is the name given to the decreasing pH of ocean water caused by the absorption of carbon dioxide from the atmosphere. Although the natural absorption of CO2 by the world’s oceans helps mitigate the climatic effects of CO2 emissions, it is believed that the resulting decrease in pH (ie making acid water) will have consequences negative, especially for oceanic calcifying organisms such as coral reefs.
Rising sea level
Observations since 1961 show that the average temperature of the global ocean has increased, even at depths of 3000 m (IPCC report), and that the ocean has absorbed more than 80% of the heat added to the climate system. This warming causes rising sea levels and creates problems for low-lying countries.
Over the past 10 years, the incidence of diseases developed in corals appear to have increased dramatically, contributing to the deterioration of coral reef communities worldwide.
Species that have been moved intentionally or not, due to human activity, in areas where they are not naturally occurring are called “invasive species.” Often natural controls such as predators and parasites of invasive species are lacking, then these species can multiply rapidly changing radically the ecosystem and local organizations out of competition. The damage caused by these species can be devastating: altered ecosystem dynamics, biodiversity loss, reduced resilience of ecosystems and loss of resources.