4G – Coastal ecosystems

Supporting article G: The threat to coastal ecosystems (from the World Resource Institute, United Nations Environmental Plan)


Threats to coastal ecosystems
Source: World Resources Institute, United Nations Environment Programme, United Nations Development Programme, and the World Bank. 1996.

Coastal ecosystems, which are one of the richest storehouses of marine biodiversity, are threatened by development related activities along roughly half of the world’s coasts.
Coastal ecosystems, which are one of the richest storehouses of marine biodiversity, are threatened by development related activities along roughly half of the world’s coasts, according to new data compiled by the World Resources Institute.

According to the estimate, about 34 percent of the world’s coasts are at high potential risk of degradation, and another 17 percent are at moderate risk. Most of the coastal ecosystems potentially threatened by development are located within northern temperate and northern equatorial zones. Europe, with 86 percent of its coasts at either high or moderate risk, and Asia, with 69 percent of its coasts in these categories, are the regions whose coastal ecosystems are most threatened by degradation.

Coastlines ranked as under a low threat were primarily within desert, subarctic, and arctic regions.

The study drew upon digitized map data and defined coastal zones to include the land area within 60 kilometers of the coast and the adjacent near shore waters. The threat estimates were derived from an index that was based on five indicators:
• Cities with populations of more than 100,000 captures potential threats from coastal development, sewage, and industrial pollution.
• Major ports measures the potential threats from species introductions (through the release of ballast water), the potential for oil spills, and industrial pollution.
• Population density measures potential threats from coastal development and pollution.
• Road density is an indirect measure of access to coastal resources and coastal development.
• Pipeline density measures the potential threat of oil pollution and of spills of other industrial wastes.

Each of the five indicators was given equal weight in the construction of a final index of potential threat to coastal ecosystems. The presence of cities and ports automatically defined those units of the coastal zone as being under a high threat. Units outside of cities and ports were defined as being under a high threat if any one of the three density indicators was high; remaining units were defined as being under a moderate threat if one or more of the density indicators were moderate.

The analysis also considered threats to currently identified national marine protected areas within 100 kilometers of continents and major islands. Within this group, about 59 percent of marine protected areas were found to be at high risk and another 14 percent were found to be at moderate risk from development related activities.

The study notes that there are many limitations in the current estimate. For example, the impacts of fishing, deforestation, and agricultural activity are not covered; human activities beyond 60 kilometers of the coast were not considered; the study did not factor in the relative sensitivities of different ecosystems to disturbance; data quality was better for some regions than for others; data modeling and mapping added additional uncertainty to the results; and pressures may have been underrepresented where they have a cumulative effect.

The current study also was at too coarse a scale to guide national management and planning activities. A second phase of the project would develop a set of more comprehensive, finer-resolution indicators.