Caribbean Sea

• Category: Marine and Oceanic Biomes.
• Geographic Location: North America.
• Summary: The Caribbean Sea region is one of the world's biodiversity hot spots; its widely varying habitats are vulnerable to the negative impacts of human impact and climate change.

An enclosed basin of the western Atlantic Ocean, the western and southern sides of the Caribbean Sea form the boundaries of Central and South America, while it encompasses the Antilles Islands chain to the east and northeast. In the northwest, the Yucatan Channel links the Caribbean to the Gulf of Mexico. Stretching for approximately 8,389 miles (13,501 kilometers), the coastal areas around the Caribbean Sea include twenty-six countries as well as nineteen territories of the United States, France, Britain, and the Netherlands. The coast is made up of coral reefs, mangroves, expanses of seagrasses, sand beaches, and rocky shores.

Millions of years ago, the Greater Caribbean was separated from the Pacific Ocean by the closing of the Isthmus of Panama. Separated by water ridges and sills, the floor of the Caribbean Sea today is comprised of the Basins of Grenada, Venezuela, Colombia, Yucatan, and the Cayman Trough. The depth is recorded at more than 7,874 feet (2,400 meters) through three-quarters of the Caribbean, but it reaches 21,326 feet (6,500 meters) in the Cayman Trough. The area of the Caribbean Sea is approximately 1.05 million square miles (2.72 million square kilometers).

Biodiversity

The Caribbean has been identified as one of the world's five hot spots for marine biodiversity. While many species remain unknown, a team of experts led by marine biologist Patricia Miloslavich in 2010 identified 12,046 species of marine life in the Caribbean.

Among the species found in the Caribbean's ecosystem is the tiny bee hummingbird, among the smallest known birds in the world, which is found only in Cuba and on the Isle of Youth. Weighing only 0.004 pound (1.8 grams), the bee hummingbird is often taken for an insect. In 2008, the smallest snake in the world was discovered on the Caribbean island of Barbados by Penn State biology professor Blair Hedges. Less than 4 inches (102 millimeters) long, this snake, named Leptotyphlops carae, looks like a strand of spaghetti. Blair determined that the snake's genetic makeup was new to science, with a unique color pattern and scales. At the other end of the size spectrum, the Caribbean Sea is home to at least two dozen species of marine mammals, from spotted dolphin (Stenella attenuata) to the humpback whale (Megaptera novaeangliae).

A total of 6,550 plant species are known in the Caribbean region. At least seven species of seagrass are present in the Caribbean Sea, with turtle grass (Thalassia testudinum) and manatee grass (Syringodium filiforme) the most widely distributed. While many animals tend to remain in a single habitat type for most of their activity cycles, a number split their time between seagrass beds, for instance, and coral reefs. Among fish, the bluestriped grunt (Haemulon sciurus) is known as a denizen of the reef, where it shelters during the day. However, the bluestripe migrates by night to seagrass beds for feeding. This behavior has been documented in both juveniles and adults; it is seen as evidence for habitat diversity in the support of maintaining strong populations of native fauna in protected areas. The interaction of mangrove-based species and reef-based species is another area of similar research.

The Atlantic hawksbill sea turtle (Eretmochelys imbricata), an endangered omnivore, depends on isolated beaches for nesting, sometimes migrating to the Caribbean from as far north as Labrador, where it feeds during summer. While enjoying some protection, the hawksbill continues to be a target of tortoiseshell poachers who trade in this illicit product.

Resident birds of the Caribbean Sea range from the common pelican (Pelecanus occidentalis) and magnificent frigatebird (Fregata magnificens) to snowy plover (Charadrius alexandrinus) and clapper rail (Rallus longirostris). Migratory species rely on many of the islands and wetlands surrounding the sea to make stopovers on their North American routes. These include the peregrine falcon and least tern.

Reefs and Atolls

The Caribbean region is home to some 65 to 75 species of hard coral and at least 500 to 700 reef-associated fish species. The center of reef biodiversity in the Caribbean region is the area around the Belize Barrier Reef, which hosts 40 to 50 species of hard coral and 80 percent of reef-associated species found in the biome. In addition to providing a home to a vast number of creatures and their ecosystems as well as offering a wealth of economic resources for local inhabitants and tourists, the reefs of the Caribbean offer crucial protection from the destructive hurricanes that frequent the region in the summer months.

More than one-fourth of all fish species in the world are found in coral reef ecosystems. Across the planet, these reefs are under threat from climate change and direct human activity. That behavior generally involves such practices as overfishing, fishing techniques that employ explosives and cyanide, and coastal development. As climate change causes temperatures to rise in oceans and seas, associated coral bleaching is a challenge to coral growth and health. In addition, increased carbon dioxide concentrations are causing seawater acidity levels to rise, a related threat to coral sustainability.

Researchers at the Global Coral Reef Monitoring Network estimate that 20 percent of coral reefs are threatened or already harshly impacted. Another 35 percent of coral reefs could be lost in the first few decades of the twenty-first century. Only 45 percent of all reefs are considered to be at low risk. Caribbean coral reefs have been affected by both global and local stressors. In the Caribbean Sea, the area occupied by corals has been reduced by 80 percent. The biological diversity and reef structure have also been reduced.

The region around the Caribbean Sea has two true barrier reefs. The largest of these is the Belize Barrier Reef, which stretches for some 137 miles (220 kilometers) from the Yucatan in southern Mexico to the Gulf of Honduras. In the southwest Caribbean, the second major barrier reef is located north of Providencia Island, Colombia. In the Caribbean, the most dominant reefs are those identified as fringing reefs, which means that they are adjacent to mainland areas or to continental islands. Fringing reefs also encircle the majority of the smaller Caribbean islands, including Aruba, Bonaire, Antigua, and the Caymans.

There are only about ten to twenty true atoll reefs in the region of the Caribbean; most of these are in the offshore area that extends from the Yucatan to Nicaragua. Unlike most of the atoll islands of the Pacific, these atolls do not appear to be volcanic. Along the coast of southern Belize lies Glover's Reef, the best-developed atoll in the region. The reefs of the Caribbean region also are distinct from those in the Indo-Pacific region in other ways, including the fact that Caribbean reefs generally do not have prominent algal ridges on reef crests. In the Indo-Pacific region, reef surfaces tend to be made up of hard corals and microalgae, while those in the Caribbean instead produce an abundant mixture of sponges and octocorals. Because of the differences present here, biodiversity is enriched and reef topography is more complex here.

In 2000, the Seaflower Biosphere Reserve was established, sponsored by the government of Colombia. This reef-based sanctuary includes about one-tenth of the Caribbean Sea. In 2005, a core area of the reserve was designated as a Marine Protected Area.

Human Impact

Environmental damage and species disruption in the Caribbean Sea have come in the form of habitat destruction resulting from the development of farm runoff, aquaculture, petrochemical exploitation, and other threats. When the habitat of an endemic species is encroached upon, by definition there is nowhere else for the species to go. At least 38 species are known to have become extinct recently in the Caribbean. Many others, such as two species of giant shrews and the Cuban crocodile, are considered critically endangered. Additionally, 48 bird species, 18 mammal species, and 143 amphibian species that are endemic to the Caribbean are now threatened. On the positive side, nearly 18,640 square miles (30,000 kilometers) have been classified as protected areas by various governments within the Caribbean region.

Since the late twentieth century, the reefs of the Caribbean area have become increasingly more vulnerable to overdevelopment along the coast and to overuse from recreational purposes. As the quality of the waters of the Caribbean Sea have been overtaxed by human uses, algae have begun to smother coral in some locales. To deal with reef degradation, Caribbean nations have identified Marine Protected Areas that are organized around protection of coral reefs and related habitats. However, environmentalists warn that much more needs to be done to adequately protect the ecosystems here. They are calling for better management of protected areas, improved monitoring of protected species and sites, stricter enforcement of environmental laws, and significant expansion of existing protected areas.

Climate change impacts in the Caribbean Sea are already particularly evident in sea-level rise, seawater temperature increase, heavier rains, and more violent hurricane events. In 2020, the Caribbean Sea hit a record high temperature. Temperatures cotninued to climb, creating dangerous conditions. In 2024, record high ocean temperatuers allowed for the earliest ever recorded Category 5 hurricane (Hurricane Beryl) to form and make landfall. Throughout the region, hurricane season is beginning earlier, and storms are often severe and classified as category 4 or 5 hurricanes. Scientific predictions for the future include a doubling of hurricane damage for every 39-inch (1-meter) rise in sea level. Beach erosion, intertidal zone habitat degradation, coral reef stress, and associated undercutting of biological diversity are among the unfortunate, but likely, outcomes.

Bibliography

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Jacobo, Julia. “Record Warm Ocean Temperatures Allowed Hurrican Beryl to Become the Earliest Category 5 Atlantic Storm.” ABC News, 1 Jul. 2024, abcnews.go.com/International/record-warm-ocean-temperatures-allowed-hurricane-beryl-become/story?id=111577484. Accessed 10 Oct. 2024.

Lewis, Emma. "World Oceans Day: The Caribbean Sea Faces Dual Threat of Climate Change and Overfishing." Global Voices, 8 June 2021, globalvoices.org/2021/06/08/world-oceans-day-the-caribbean-sea-faces-dual-threat-of-climate-change-and-overfishing/. Accessed 10 Oct. 2024.

McKeown, Alice. “Coral Reefs under Threat.” World Watch, vol. 23, no. 1, 2010.

Miloslavich, Patricia, et al., editors. Caribbean Marine Biodiversity: The Known and Unknown. DEStech Publications, 2005.

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Schrope, Mark. “Conservation: Providential Outcome.” Nature, vol. 451, no. 1, 2008.

Spalding, Mark. A Guide to the Coral Reefs of the Caribbean. U of California P, 2004.