Defying Ocean's End: An Agenda For Action

By Linda Glover, Sylvia Earle and Graeme Kelleher

If humankind were given a mandate to do everything in our power to undermine the earth's functioning, we could hardly do a better job than we have in the past thirty years on the world's oceans, both by what we are putting into it-millions of tons of trash and toxic materials-and by what we are taking out of it-millions of tons of wildlife. Yet only recently have we begun to understand the scale of those impacts.

Defying Ocean's End is the result of an unprecedented effort among the world's largest environmental organizations, scientists, the business community, media, and international governments to address these marine issues. In June 2003, in the culmination of a year-long effort, they met specifically to develop a comprehensive and achievable agenda to reverse the decline in health of the world's oceans.

As conservation organizations begin to expand their focus from land issues to include a major focus on preservation of the sea, it is increasingly apparent that we have to approach marine conservation differently and at much larger scale than we have to date. What's also clear is the magnitude and immediacy of the growing ocean concerns are such that no one organization can handle the job alone.

Defying Ocean's End is a bold step in bringing the resources needed to bear on this vast problem before it is too late. It offers a broad strategy, a practical plan with priorities and costs, aimed at mobilizing the forces needed to bring about a "sea change" of favorable attitudes, actions, and outcomes for the oceans-and for all of us.

• Language: English
• Publisher: Island Press
• Release date: Sep 26, 2012
• ISBN: 9781597267519

Book preview

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CHAPTER 1

The Caribbean

Mark Spalding, University of Cambridge

Philip Kramer, The Nature Conservancy

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Introduction

The Caribbean Region, for the purposes of this study, is an area comprising the Caribbean Sea, the Gulf of Mexico and the adjacent areas of the Bahamas and Turks and Caicos. This is a region of considerable geological, biological and political complexity (Figure 1) but also one of internal integrity, a partially closed series of basins having relatively little interplay with adjacent regions. The region is often referred to as the Wider Caribbean, the Intra-Americas Sea or the American Mediterranean. It provides an excellent case study for considering both human impacts in the marine realm and the measures required for their mitigation. Three features underpin this value:

Biological complexity. The region encompasses the heart of Atlantic species biodiversity and is host to considerable numbers of endemic species—those found only in a geographically restricted area and nowhere else in the world. This is well documented for shallow coastal communities (Tomlinson 1986, Veron 1995, Spalding, Blasco & Field 1997, Spalding, Ravilious & Green 2001, Spalding et al 2003), and there is now growing evidence for similar patterns in deeper water species (Smith, Carpenter & Waller 2002).

Socio-political complexity. This small region includes 35 countries and territories covering a complete spectrum of political systems and economic regimes, including the world’s richest nation alongside some of the world’s poorest (Schumacher, Hoagland & Gaines 1996). The history of human activity in the region has had a major role in the current status of the marine environment.

Pressure. Humans have had some influence over parts of the marine environment in the Caribbean for millennia (Jackson et al 2001), but there is no doubt that current pressures are unparalleled (Burke & Maidens 2004). This case study was prepared for the Defying Ocean’s End

Conference in Los Cabos, Mexico, in May/June 2003. We commence with an overview of the physical and biological geography of the region, then focus on the range of human stresses affecting the marine environment and finally consider the options for reversing the current trends of rapid environmental decline.

Natural History

Physical geography

The region under consideration consists of two semi-enclosed basins—the Caribbean Sea and the Gulf of Mexico—as well as the westernmost embayment of the Atlantic Ocean. Bounded to the west and south by Central and South America, the Caribbean is bounded to the north by the Greater Antilles (Cuba to Puerto Rico) and to the east by the great arc of small islands called the Lesser Antilles.

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Figure 1 The many Exclusive Economic Zone (EEZ) and Fishery Zone (FZ) claims in the Caribbean region complicate regional conservation schemes.

Most of the Caribbean Sea is centered on the Caribbean Plate, a relatively small tectonic plate (section of Earth’s crust) that formed between 75 and 90 million years ago. The movements of this plate form subduction zones to the east and west (where one plate slides beneath another) and transform boundaries (where two tectonic plates slide past each other) to the north and south. These tectonic interactions have created the island chains of the Greater and Lesser Antilles as well as the mountainous perimeters across Central America and the southern Caribbean Sea. Most of the remainder of the region lies on the North American Plate (Pindell 1994, Meschede & Frisch 1998).

The Caribbean Sea is itself divided into four smaller basins separated by shallower ridges, while the Gulf of Mexico can be considered a separate fifth deep basin. Deep trenches are found to the north of Puerto Rico and to the south of Cuba and the Cayman Islands. The basins, as well as the deep trenches, are isolated from each other by shallow underwater sills and, although there is some water exchange, each may contain unique and important features (Tomczak & Godfrey 1994, Smith, Carpenter & Waller 2002). With the exception of the Bahamas Banks, the only extensive shallow areas are on the continental shelves, notably around the southern U.S. coast, the northern coast of the Yucatan Peninsula and the Nicaraguan Rise.

Surface water movement is driven by the North Equatorial Current and the North Brazil (or Guiana) Current. These combine to form the Antilles Current, which sweeps up the outer edge of the Lesser Antilles and the eastern side of the Bahamas. There is also considerable flow between the Lesser Antilles islands, and to a lesser degree through the channels of the eastern Greater Antilles, creating a broad westward-flowing Caribbean Current across the Caribbean Sea. This current is weak and there are surface eddies creating a relatively complex pattern of surface flow. Further west, the water flow is concentrated through the Yucatan Channel and becomes much stronger. Once in the Gulf of Mexico, this current flows northwest, then in a broad clockwise circle —the Loop Current—which flows back southward along Florida’s west coast, shedding eddies westward into the Gulf before leaving the system east of Florida. The Florida Current, enhanced by flow from the Antilles Current, forms a broad stream of warm water—the Gulf Stream—which flows northeast across the Atlantic (Tomczak & Godfrey 1994, Longhurst 1998).

Rivers have a considerable influence in the southeast Caribbean, where outflows of the Amazon and Orinoco Rivers create slightly lower salinities and more suspended sediments over wide areas (Tomczak & Godfrey 1994).

Deep water flows into the Caribbean Sea through a limited number of deep passes: through the Jungfern Passage east of Puerto Rico into the Venezuela and Colombian Basins, through the Windward Passage east of Cuba into the Cayman and Yucatan Basins and through a number of eastern passages into the Aves and Grenada Basins. The deeper water areas have remarkably consistent temperatures. Little is known about the turnover of deep water in the Caribbean basins, but most estimates suggest periods of hundreds of years (Tomczak & Godfrey 1994, Tyler 2003).

Biodiversity

The Caribbean is perhaps best known for its tropical shallow marine ecosystems. Its coral reefs cover about 20,000 square kilometers (Spalding, Ravilious & Green 2001). This is only about 7% of the world’s shallow reefs, but they are of enormous biological and human importance. Biologically they are unique, with very little overlap in species with other parts of the world—except for Brazil and to a small degree West Africa, both of which have related assemblages but fewer species (Cortés 2003). The Caribbean is also a center of diversity and endemism for some mangrove and seagrass species, although a higher proportion of these extends into the Eastern Pacific and across to West Africa. The Caribbean has roughly 22,000 square kilometers of mangrove (amended from Spalding, Blasco & Field 1997), which is about 12% of the global total. No accurate estimate of the extent of seagrass area is available, although the Caribbean is likely to be a highly significant region for these habitats (Onuf et al 2003, Creed, Phillips & Van Tussenbroek 2003). Unpublished estimates from work at the United Nations Environment Programme (UNEP) World Conservation Monitoring Centre suggest as much as 33,000 square kilometers of Caribbean seagrass beds (Spalding et al 2003), which would be about 18 to 19% of the global