What are LMEs?
Between the world’s continental margins and the open ocean are 66 Large Marine Ecosystems or LMEs (map). These are vast regions of coastal ocean space of 200,000 km2 or more, extending from river basins and estuaries seaward to the continental shelf break or slope or to the outward margins of major current systems. Unique defining ecological criteria of LMEs include bottom depth contours, currents and water mass structure, marine productivity, and food webs. A common feature, however, is that all LMEs are transboundary in nature by virtue of interconnected currents, movement and migration of living resources, and pollution that straddle political boundaries. Since Dr. Kenneth Sherman and colleagues developed the LME concept in 1991, the LME has been widely adopted as the geographical unit for ecosystem-based management of coastal marine areas and their living resources. In fact, LMEs have become a rallying point for countries to cooperate in addressing problems relating to the utilization of transboundary resources. In addition to LMEs, the TWAP LMEs component has also assessed the Western Pacific Warm Pool (WPWP). This is an immense area of open-ocean warm water in the Western Pacific Ocean north of Papua New Guinea with dimensions that fluctuate annually as this warm water body expands and contracts (map). The WPWP is not an LME due to its open ocean geographic location and physical characteristics that differ from LME defining criteria.
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1: East Bering Sea

2: Gulf of Alaska

3: California Current

4: Gulf of California

5: Gulf of Mexico

6: Southeast U.S. Continental Shelf

7: Northeast U.S. Continental Shelf

8: Scotian Shelf

9: Labrador - Newfoundland

10: Insular Pacific-Hawaiian

11: Pacific Central-American Coastal

12: Caribbean Sea

13: Humboldt Current

14: Patagonian Shelf

15: South Brazil Shelf

16: East Brazil Shelf

17: North Brazil Shelf

18: Canadian Eastern Arctic - West Greenland

19: Greenland Sea

20: Barents Sea

21: Norwegian Sea

22: North Sea

23: Baltic Sea

24: Celtic-Biscay Shelf

25: Iberian Coastal

26: Mediterranean Sea

27: Canary Current

28: Guinea Current

29: Benguela Current

30: Agulhas Current

31: Somali Coastal Current

32: Arabian Sea

33: Red Sea

34: Bay of Bengal

35: Gulf of Thailand

36: South China Sea

37: Sulu-Celebes Sea

38: Indonesian Sea

39: North Australian Shelf

40: Northeast Australian Shelf

41: East Central Australian Shelf

42: Southeast Australian Shelf

43: South West Australian Shelf

44: West Central Australian Shelf

45: Northwest Australian Shelf

46: New Zealand Shelf

47: East China Sea

48: Yellow Sea

49: Kuroshio Current

50: Sea of Japan

51: Oyashio Current

52: Sea of Okhotsk

53: West Bering Sea

54: Northern Bering - Chukchi Seas

55: Beaufort Sea

56: East Siberian Sea

57: Laptev Sea

58: Kara Sea

59: Iceland Shelf and Sea

60: Faroe Plateau

61: Antarctica

62: Black Sea

63: Hudson Bay Complex

64: Central Arctic

65: Aleutian Islands

66: Canadian High Arctic - North Greenland

Socio-economic importance of LMEs
With some of the planet’s most productive waters and biodiverse habitats such as coral reefs and mangroves, LMEs provide important ecosystem goods and services (pop-up definition here) that translate into livelihoods, income, food security, and other benefits for millions of people around the world. For example, more than 80 percent of the world’s marine fish catch comes from LMEs. These water bodies are the focus of the vast majority of ocean-related sectoral activities, including fisheries, tourism, shipping, and oil and gas exploitation, contributing an estimated $12 trillion annually to the global economy.

Changing status of LME health
A potent combination of anthropogenic and natural stressors is jeopardizing the health and productivity of LMEs and threatening their sustainability. Over-fishing, increasing land and marine-based pollution, invasive alien species, and habitat degradation and loss are now all too common in coastal areas. It is within the boundaries of the LMEs that overfishing and the degradation of marine habitats is most severe, coastal pollution is concentrated, and levels of eutrophication are increasing. Exacerbating these conventional stressors are more recent threats in the form of climate change and ocean acidification. In the majority of cases these threats are accelerating, and without concerted action their impacts could become irreversible. Despite a range of mitigating actions, the health of many LMEs remains in decline.

The Global Environment Facility’s support for LMEs
The Global Environment Facility (GEF) remains the world’s largest supporter of transboundary water projects through which countries are provided with financial, scientific, and technical assistance to address the negative trends evident in LMEs and to achieve the ecosystem-specific targets of the 2002 World Summit on Sustainable Development Plan of Implementation to which nearly 200 countries have agreed (pop up or link here- see below). Since the early 1990s, the GEF has provided grants totaling around $380 million to 20 LME projects involving 122 countries in Asia, Africa, Latin America, and Eastern Europe (map showing LME projects). This is supplemented by an additional $2.35 billion in cofinancing from the project countries and diverse partners. Related WSSD targets:
  • Achievement of substantial reductions in land-based sources of pollution by 2006
  • Introduction of an ecosystems approach to marine resource assessment and management by 2010
  • Designation of a network of marine protected areas by 2012
  • Maintenance and restoration of fish stocks to maximum sustainable yield levels by 2015)

TWAP LMEs Assessment Methodology
In 2010 a Working Group of institutional partners and experts, coordinated by the IOC, developed an indicator-based methodology for assessment of LMEs. The methodology report can be downloaded from http://www.geftwap.org/project-results-and-reports/methodologies-for-the-gef-transboundary-assessment-programme-1/methodologies-for-the-gef-transboundary-assessment-programme. This methodology built on the existing approach for assessment and management of LMEs that is based on five modules: Productivity, Fish and Fisheries, Pollution and Ecosystem Health, Socioeconomics, and Governance. A conceptual framework was developed that shows the link between the human and natural systems, to help facilitate the assessment of the impacts of human and natural stressors on LME health and provision of ecosystem goods and services, and consequences for humans and implications for governance of these water bodies.

LMEs Conceptual Framework
Illustration created with support of ESA graphic service, BY-SA-4.0Credit: IOC-UNESCO, Methodology for the Assessment of the Open Ocean (2011)

Key framing questions that the assessment sought to answer included:
  • What are the current trends in LMEs and the main drivers?
  • Which LMEs are most heavily impacted (for each theme and overall)?
  • Which ecosystem services are most at risk?
  • What are the implications for humans?
  • Where is human dependency greatest on LME ecosystem services?
  • Where are humans most vulnerable to changes in LME condition?
  • What is the status of the governance architecture in transboundary LMEs?
  • What are the emerging issues?
The assessment focused on a global comparative assessment of LMEs using a suite of indicators, with results presented in the LMEs Assessment Report and Summary for Policy Makers (link to reports). Results for individual LMEs are presented in electronic fact sheets on this web portal.