Threats to habitats

Natural and human causes

Physical degradation or destruction of habitats may be caused by a variety of natural causes including cyclones, hurricanes, typhoons, volcanism, earthquakes and tsunamis. These factors can cause significant physical damage to the structure of habitat, thus altering biological diversity and ecosystem function.

Global climate change and periodic climatic events are a significant threat to habitats on the global scale, particularly to coral reefs. The increase in sea-surface temperature associated with the major El Niño and La Niña climate switches in 1997-1998 resulted in extensive coral bleaching and mortality over large portions of the Indian Ocean and Southeast and East Asia. Some of the changes caused by periodic climate events are not necessarily permanent. However, direct human-induced stresses to habitats often exacerbate the effects these events or limit the recovery capability of marine and coastal ecosystems.

Direct human activities posing threats to marine and coastal habitats are relatively well documented. Each of these activities may independently threaten ecosystem structure and function. However, more significant impacts are often the result of compounded effects of multiple activities. These direct threats include:
· Overexploitation
· Coastal Development
· Destructive Fishing Practices
· Mining
· Land-based Pollution
· Marine-Based Pollution
· Recreational Misuse
· Aquaculture

Underlying these direct threats are often societal components contributing to the destructive activities. Some of these driving factors may be incomplete knowledge, lack of conviction, inadequate laws or regulatory regimes, lack of economic alternatives, high population growth, lack of effective management or limited human or financial resources. In considering appropriate response measures to address destructive human activities, it is important to identify and address the underlying causes as well as the proximate threats.