Massive oil spills and new offshore drilling in the Gulf of Mexico and around the world are threatening sea turtle nesting beaches and the oceans where they spend most of their lives. We call it the fossil fuel frenzy because it is happening everywhere there is any oil or gas left under the ocean. All seven species of sea turtles are endangered or threatened, and most populations are in decline due to human activities including bycatch in commercial fisheries, plastics pollution, poaching and climate change. Oil and gas accidents and operations add a deadly risk to their already precarious status. Read more or Download as a PDF.
Gulf of Mexico BP Oil Spill and Sea Turtles
The catastrophic BP oil spill began as the critically endangered Kempís ridley sea turtle was migrating along the Louisiana coast to nest on Texas and Mexico beaches, exposing them to the heart of the spill. Loggerhead sea turtles were also nesting in the Gulf, a species declining so quickly that it is now proposed for uplisting to endangered under the U.S. Endangered Species Act. Kempís ridley sea turtles washed up on Gulf shores, many of them juvenile sea turtles, the size of dinner plates, found ill and dying due to exposure to and ingestion of oil. The number of Kempís ridley nests decreased significantly both in Texas and at Rancho Nuevo, Mexico, in 2010 after decades of steady increases. The long, slow recovery of the species has been severely compromised. The Kempís may be the only species forced to survive the two biggest accidental oil spills in history: the BP Oil Spill (210 million gallons) and the Ixtoc (Ish-toc) in 1979 at 140 million gallons off the coast of Mexico.
During the BP oil spill and its aftermath, more than 1,000 sea turtles, almost 100 dolphins and other marine mammals and more than 8,000 birds were recovered dead or dying. Most of the sea turtles found were critically endangered Kempís ridley sea turtles, few visibly oiled. Biologists believe that many were accidentally caught and killed by shrimp trawlers and other commercial fishing boats before Gulf waters were closed due to the oil spill. A spike of 85 strandings in Mississippi was attributed to shrimp trawls, perhaps due to the high abundance of skimmer trawls in the area that are not required to install Turtle Excluder Devices.
Nearly 300 loggerhead nests were relocated to the Atlantic Coast of Florida from the Gulf for hatching. About 13,000 hatchlings were ultimately released into the Atlantic. Leatherbacks, olive ridleys, green, and hawksbill sea turtles also inhabit the Gulf but it is less clear what the exact impacts to these species will be.
How Oil Harms Sea Turtles
- Oil wreaks havoc on adult, juvenile, and developing sea turtles as it disrupts normal biological functions, ecological interactions, and basic physical processes. The toxic effects of oil exposure predict a dire situation for the Gulfís sea turtles for years to come.
- Harm to Adults: Sea turtles are not known to avoid oil slicks. Several adults were tracked heading directly for the oil spill. Adults will migrate into and through an oil slick to their nesting beaches, deeply inhaling toxic fumes when surfacing for air in the oil slick. When the oil is fresh, concentrated vapors can limit the ability of the turtleís blood to hold oxygen. Oil exposure impairs the olfactory system of sea turtles, which plays a key role in navigation during migration.
- Adult sea turtles ingest tar balls and marine life that is covered in oil, creating both physical blockages in their digestive system and toxic effects on metabolism. When an oil slick reaches shore, dense aggregations of oils and tar form at the high tide line, and nesting females must cross through it.
- Oil Harms Nests and Eggs Sea turtles typically migrate to the same nesting beach where they hatched, and if the beach is oiled, the result can be disastrous for reproduction. Oiled sand may not support the natural processes needed for successful egg incubation. Oiled sand raises the normal temperature of the nest, which is critical to embryo survival as well as the male/female ratio of the developing embryos. Oxygen diffusion deep into the nest is critical to normal embryo development. If either the nesting sand or sea turtle eggs are oiled, they may suffer lack of oxygen malformation, or even death. Carcinogens and toxins in the oil mixtures can penetrate the permeable egg and result in malformation of embryos and death. Developing blood vessels are especially prone to oil toxicity, which also impairs the ability of the blood to carry oxygen.
- Hatchlings Newborn hatchlings are at extremely high risk from the effects of an oil spill due to their small size, habitat use, and feeding behavior. Their small size equals a greater surface-area-to-volume ratio, a basic physical characteristic that dooms them to extremely high oil exposure. Their soft carapace and developing organs are more permeable and susceptible to the toxic effects of oil exposure. Hatchlings spend the majority of their life very close to the surface where the highest concentrations of oil are likely to be encountered. Their feeding behavior consists of ingesting anything that looks like food, and hatchlings are regularly observed eating tar balls and plastic debris. Hatchlings imprint to the beach they emerge from, and when hydrocarbon exposure disturbs their olfactory system it jeopardizes this critical behavior.
- Food Sea turtles rely on the productive ecology of the Gulf estuary and pelagic zones for their diet. Oysters and clams will absorb the oil and become toxic. Crabs and fish contaminated with oily hydrocarbons are eaten by foraging sea turtles, which are likely to encounter dangerous pockets of tar as they search for food. The early life stages of marine invertebrates such as oysters, crabs, and sponges are highly sensitive to the toxic effects of hydrocarbons. Areas inundated with oil are likely to be devoid of any life able to support healthy sea turtle populations, forcing new foraging strategies and reliance on invertebrate food sources less sensitive to hydrocarbon toxicity, such as jellyfish.
- Oil and gas facility construction and operation Lighting from industrial facilities on or near nesting beaches causes hatchling disorientation leading to their deaths and the decline of sea turtle populations. Underwater blasting, dredging and seismic testing during construction and operations can kill and displace sea turtles. Large ports with lengthy jetties near nesting beaches or feeding areas can also harm and displace sea turtles.