Gulf of Mexico ecosystem

• Category: Marine and Oceanic Biomes.
• Geographic Location: North and Central America.
• Summary: The Gulf of Mexico contains great biodiversity, from shallow coral reefs to mysterious deeps to more than half of all the coastal wetlands of the United States. Rich in biodiversity, these waters are vulnerable to intensive human activity.

The Gulf of Mexico is an arm of the Atlantic Ocean that extends for about 700,000 square miles (1.8 million square kilometers), forming the marine border between the extreme southeastern section of the United States and eastern Mexico, and between the United States and northern Cuba. The gulf flows for more than 1,100 miles (1,770 kilometers) from west to east and for some 800 miles (1,287 kilometers) from north to south. The Gulf of Mexico flows into the North Atlantic Ocean past northern Cuba, by way of the Straits of Florida. Along southern Cuba, the Gulf of Mexico merges with the Caribbean Sea via the Yucatán Channel.

As warm water from the Caribbean flows into the gulf, it creates a loop current along the coasts. In the Florida Straits, that loop current turns into the Florida Current as it exits and joins with the Gulf Stream. The largest lobes of the Gulf of Mexico are the Bay of Campeche in Mexico, and Apalachee Bay in Florida. At 12,714 feet (3,875 meters), the deepest part of the gulf is Sigsbee Deep, 875 miles (1,408 kilometers) off the coast of Mexico.

The largest river, by far, that empties into the gulf is the Mississippi. Other major flows come from the Alabama, Brazos, and Rio Grande Rivers. The chief ports of the gulf are Tampa and Pensacola in Florida, Mobile in Alabama, New Orleans in Louisiana, Galveston and Corpus Christi in Texas, Tampico and Veracruz in Mexico, and Havana in Cuba. In the United States, the Intracoastal Waterway runs along the northern coast of the gulf. Along the shores of the Gulf of Mexico, the land tends to be low, sandy, and marshy.

More than half of all coastal wetlands in the United States are located in the Gulf of Mexico. Louisiana alone is home to 40 percent of all American coastal wetlands. According to the National Oceanic and Atmospheric Administration (NOAA) in 2022, from 1996 to 2016, the latest national data available, 640,000 acres (258,999 hectares) of coastal wetlands in the United States were lost. A total 90 percent of all U.S. coastal wetlands loss occurs in Louisiana.

Biodiversity

The complex ecosystem of the Gulf of Mexico includes open water columns, floating sargassum mats, deep-sea soft coral, hard coral reefs, sandy bottom, muddy bottom, marshes, submerged aquatic vegetation, bays, lagoons, and sandy beaches where sea turtles lay their eggs. Shrimp is the major commercial fishery in the gulf; the diverse aquatic habitats here support brown shrimp, white shrimp, pink shrimp, royal red shrimp, seabobs, and rock shrimp (although neither seabobs nor rock shrimp are much prized by commercial fishers).

Whale species include Bryde whales and sperm whales, an endangered species. Other cetaceans that frequent the gulf are the dwarf sperm whale, pygmy sperm whale, Blainville’s beaked whale, Gervais’s beaked whale, short-finned pilot whale, killer whale, false killer whale, and pygmy killer whale. Bottlenose dolphin, Atlantic spotted dolphin, Risso’s dolphin, rough-toothed dolphin, Fraser’s dolphin, pantropical spotted dolphin, striped dolphin, Clymene dolphin, and spinner dolphin are either permanent or seasonal residents here. All these species are protected under the Marine Mammal Protection Act. Five species of sea turtles also live in the gulf: the endangered Kemp’s Ridley turtle, and the leatherback, loggerhead, green, and hawksbill. The olive Ridley, a threatened species, can sometimes, but only rarely, be found in the gulf.

Disasters: Natural and Human-Made

An event that threatened Gulf of Mexico habitats and species was the April 2010 BP Deepwater Horizon oil blowout off the coast of Louisiana. By November 2010, the U.S. Fish and Wildlife Service had issued a report on damage, declaring that 6,000 birds, 600 sea turtles, and 100 mammals had died within the spill area. Experts believed that the actual count was much higher because so many dead animals had not been found. Researchers also located dozens of dead and dying coral deposits. An ecologist from the Lawrence Berkeley National Laboratory discovered a new species of bacteria that guzzled oil and was able to survive up to 3,600 feet (1,097 meters) below the surface. Great concern over the effects of the dispersant Corexit on the biota—BP pumped massive quantities of the toxic brew into Gulf waters—remains an open question.

Assessing damage to marine ecosystems in light of the disaster, the International Union for Conservation of Nature (IUCN) determined that there were 15,419 recorded species of marine life in the Gulf of Mexico, 10 percent of which were endemic, or found nowhere else on Earth. The IUCN Red List identified 53 threatened and 29 near-threatened species, including five of 28 mammals, all five species of sea turtles, 43 of 131 species of sharks and rays, more than half of the 22 species of groupers, and three of 40 species of seabirds. Also in jeopardy: two of nine seagrasses, and 11 of 60 reef-building corals.

Starting in the 1980s, a large dead zone—with insufficient oxygen to support marine life—was discovered some 60 miles (97 kilometers) off the coast of Louisiana and Texas. By 2021, scientists said it was about 6,334 square miles (16,405 square kilometers) in size. It is thought to be the result of nitrate- and phosphate-rich agricultural runoff, particularly from fertilizers used far up the Mississippi River basin in the Corn Belt. There is evidence that some species of fish, such as the female croaker, are already showing physical abnormalities because of oxygen depletion. Conservationists cite the 1990s dead-zone reversal in the Black Sea as an example that could be a goal for here.

Also threatening marine life in the Gulf of Mexico are hurricanes, such as Hurricane Delta in 2020 and Hurricane Grace in 2021. While large marine animals such as whales and sharks usually swim to calmer waters during hurricanes, slow-moving smaller animals such as turtles and shellfish often die because of rough undercurrents and quick changes in water temperature and salinity.

Anticipated climate change impacts in the Gulf of Mexico include rising sea levels, increased storm activity, collapsing fisheries, and toxic tides. Coral reefs are at risk from rising seawater temperature, which tends to drive away their symbiotic caretaker species and leads to bleaching events. According to a 2022 UN report, even if humanity manages to limit global warming to 34.7 degrees Fahrenheit (1.5 degrees Celsius), there is a higher probability that storms in the area may become major hurricanes. As the polar ice caps melt, the Gulf Coast is seriously threatened by rising sea levels.

In 2024, a report by the University of Texas, based on a multi-year study, stated the Gulf of Mexico saw the rise of the adjacent sea level at a rate two to three times as fast as the global average. Other reports suggested records show an unprecidented rise over the previous 120 years. Several factors contributed to this phenomenon. This included a combination of warmer waters and new circulation patterns of wind. This, in turn, degraded seagrass habitats. This was a serious development as seagrasses are the food source of many species of fish, some of which provide the economic means to support commercial fisheries. In addition, seagrasses store carbon. 

Changed climatic conditions in the Gulf of Mexico have also resulted in hurricanes of increased strength and destructiveness. In October 2024, Hurricane Milton impacted the state of Florida. Milton had achieved speeds of up to 175 miles per hour, uncommon in hurricanes occurring in the month of October. Warm water in the Gulf, which had reached record high temperatures, intensified both not only the speed of the hurricane but also its size. Hurricane Milton resulted in heavy destruction to both human and natural habitats, as well as heavy flooding in Gulf of Mexico coastal areas.  

Bibliography

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Dangendorf, Sönke, et al. "Acceleration of U.S. Southeast and Gulf Coast Sea-Level Rise Amplified by Internal Climate Variability. Nature Communications, 10 Apr. 2023, www.nature.com/articles/s41467-023-37649-9. Accessed 21 Oct. 2024.

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"Vital Seagrasses in Gulf of Mexico Are Retreating Amid Rapid Sea Level Rise." University of Texas News, 27 Feb. 2024, news.utexas.edu/2024/02/27/vital-seagrasses-in-gulf-of-mexico-are-retreating-amid-rapid-sea-level-rise. Accessed 21 Oct. 2024.