Consequences of the oil spill impact Brazilian sea turtles

Sea turtles are an important ecological marker and a recent study made an interesting retrospective about

by Lorenzo Ciotti
Consequences of the oil spill impact Brazilian sea turtles
© Mark Kolbe / Staff Getty Images

The impact on the environment of oil spills always takes the form of environmental disasters, as they devastate the ecosystems and biomes they affect, destroying their peculiar environments.

Sea turtles are among the species most threatened by these ecological disasters. Sea turtles can be found in all oceans except the polar regions. The flatback sea turtle is found exclusively on the northern coast of Australia. The Kemp's turtle is found exclusively in the Gulf of Mexico and along the east coast of the United States. In the oceans, sea turtles, especially green sea turtles, are among the very few creatures (manatees are another) that feed on sea grass.

Sea grass must be constantly cut to help it grow on the seabed. Sea turtle grazing helps maintain the health of kelp beds. Seagrass beds provide breeding and development grounds for numerous marine animals. Without them, many human-harvested marine species would be lost, as would lower levels of the food chain. The reactions could lead to many more marine species ultimately endangered or extinct.

Sea turtle
Sea turtle© Cameron Spencer / Staff Getty Images

The study The impact of chronic and acute problems on sea turtles: The consequences of the oil spill and ingestion of anthropogenic debris on the tropical semi-arid coast of Ceará, Brazil, published on the Aquatic toxicology, made an interesting retrospective on the topic , of which you can read an abstract below.

The researchers explained: “Sea turtle mortality is often related to materials reaching the coast from different anthropogenic activities around the world. This study aimed to investigate whether sea turtle mortality was related to old marine problems, such as litter solids, or one of the largest oil spill incidents on the Brazilian coast, which occurred in 2019.

We asked three questions: 1) Are there solid residues in the digestive tract samples and which type is the most abundant? 2) Meso marine pollutants and macro can cause mortality? 3) Is the dark material found really oil? A total of 25 samples of gastrointestinal contents (GC) were obtained, of which 22 ingested wastes of anthropogenic origin and 18 were subjected to necropsy.

These 22 samples were obtained during or after the 2019 oil spill, of which 17 samples were affected, allowing oil ingestion to be suggested with the cause of death in animals that could be necropsied. Macroscopic data showed that the most abundant solid waste was plastic (76.05%), followed by textiles (12.18%) and petroleum-like materials. However, chemical data confirmed only three samples with oil levels ranging from residual to high.

It was possible to deduce possible causes of death in 16 of the 18 total cases subjected to necropsy: the majority of deaths were due to respiratory arrest (62.5%), followed by pulmonary edema (12.5%), cachexia syndrome ( 12.5%), circulatory shock (6.25%) and head trauma (6.25%), which may have been caused by contact with solid waste, oil or both.

The study demonstrated that not all dark material found in the GCs of turtles killed in oil-producing areas is truly oil and, in this sense, a chemical analysis step to demonstrate the presence of oil needs to be added to international protocols."