The cumulative impact of human activities, under categories such as fishing, climate change, shipping and pollution, can now be viewed on Google Earth1. The Marine Impacts map shows that the areas most highly affected are the North Sea, the South and East China Seas, and the Bering Sea. The coastal areas of Europe, North America, the Caribbean, and South East Asia are also showing significant impact from human activities.
A team of researchers, led by scientists at the National Center for Ecological Analysis and Synthesis, USA, believe that to manage and conserve the world's oceans it is necessary to look at the big picture. They brought together data on the distribution and intensity of human intervention and overlapped this with the degree of impact on various marine ecosystems. In the past, studies have focused on a single activity or isolated ecosystem.
The researchers estimated the vulnerability of twenty types of marine ecosystem, such as mangrove forests, coral reefs and kelp forests. For example, they found that fertiliser run-off had a larger effect on coral reefs than on kelp forests. Almost half of the world's coral reefs were found to be heavily damaged, and other concerns were with continental shelves, sea grass beds and rocky reefs. Soft-bottom ecosystems and open ocean fared better, but few areas were untouched by human activity. Polar oceans were the least affected, but are vulnerable as ice sheets melt.
Using the impact map, efforts can be targeted to protect the ocean where it remains relatively unaffected by human activity and to keep it in good condition. For example,'no-take' zones, where fishing is not allowed, have been found to help improve the condition of ecosystems, and navigation routes can be altered to protect the most sensitive sites. These results, when supported by more detailed research at local level, could inform conservation decisions and ensure that commercial activities are carried out in a sustainable way.