Since the United Nations Conference on Environment and Development (UNCED), concern has been expressed over the deteriorating condition of the world’s coastal ecosystems that produce most of the global living marine resources.

Within the near-shore areas and extending seaward around the margins of global land masses, coastal ecosystems are being subjected to increased stress from toxic effluents, habitat degradation, excessive nutrient loadings, harmful algal blooms, emergent diseases, fallout from aerosol contaminants, and episodic losses of living marine resources from pollution and over-exploitation.
Coastal pollution, changes in biodiversity, the degraded states of fish stocks, and the loss of coastal habitat are limiting the achievement of the full economic potential of coastal ecosystems.
The efforts deployed to address these problems by local, regional, national, and international institutions responsible for resource stewardship have been less than successful. Informed decisions for ensuring the long-term development and sustainability of coastal marine resources can best be made when based on sound scientifically-derived options. But for most coastal ecosystems, existing environmental data pertinent to studies of perturbations to habitats and populations at the species, population, community, and ecosystem level are difficult to synthesise because of their spatially and temporally fragmented character, lack of comparability, and inaccessibility. To overcome these shortcomings, a more coherent and integrative assessment of the changing states of coastal ecosystems, from drainage basins to the adjacent marine ecosystems and directly linked to institutions responsible for the governance of the ecosystems, is needed.

The Large Marine Ecosystems concept is an ecological framework that can serve as a basis for achieving the UNCED objectives.The Large Marine Ecosystems are relatively large regions about 200,000 km2 or larger, characterized by distinct bathymetry, hydrography, productivity, and trophically-dependent populations.

They are regions of the ocean encompassing coastal areas from river basins and estuaries to the outer boundary of continental shelves and the seaward margins of coastal fish and other renewable resources, coastal zone damage, habitat losses, river basins and current systems. LMEs are increasingly being subjected to stress from growing exploitation of dumping of urban wastes, and fallout from aerosol contaminants. Based on these criteria, 49 distinct LMEs have been described around the margins of the Atlantic, Pacific, and Indian Oceans.

The assessments of the changing states of LMEs are based on information obtained from five (5) operational modules that link science-based information to socio-economic benefits for countries bordering on the LMEs. The five modules are focused on:
1. ecosystem productivity,

2. ecosystem fish and fisheries,

3. ecosystem pollution and health,

4. ecosystem socio-economic conditions, and

5. ecosystem governance protocols.