Brazil’s beaches are awash with oil but no one knows quite where it’s coming from. The oil spill is affecting a number of beaches on Brazil’s north-eastern coastline, and is harming turtles and other wildlife in the country’s waters.

Identified in 105 locations in eight different states this month, the oil has so far killed at least six turtles and a bird, although fish and shellfish are currently uncontaminated. A total of 46 cities, as well as a number of tourist beaches, have witnessed thick black oil washing up on their sand.

So where is the oil coming from? Strangely, molecular analysis by state oil company Petrobas concluded that the oil was not produced by Brazil and had come from a single source. The exact nature of this source is yet to be determined and an investigation is currently underway. The investigation is being carried out by the Brazilian Institute of Environment and Renewable Natural Resources (Ibama), the Federal District Fire Department, the Brazilian Navy, and Petrobas. A team of around 100 people are currently working on a clean-up operation.

Ibama notes in a statement that while the situation in certain states such as Rio Grande do Norte appears to have stabilized, new oil is washing up in other locations, such as Maranhão. While some animals have been killed by the oil, two turtles have been rescued and returned to the sea. Meanwhile, an olive ridley turtle was taken to the Costa Cetacean Project to be rehabilitated.

For anyone who comes across an affected animal, Ibama advises immediately contacting environmental organizations such as Instituto Verdeluz so that experts may attend to the animal. “The animal must not be washed or returned to the sea prior to veterinary assessment,” they write. They also warn bathers and fishers to avoid coming into contact with the oil.

It is believed the oil might have been spilled by a tanker transporting the fuel far from Brazil’s coastline, BBC News reports. A couple of barrels have washed up on beaches on the coast of Sergipe state.

The lack of certainty around the source of the substance is of grave concern to environmentalists.

“The surveillance in our waters, no matter if this was an intentional or an unintentional spill, is too fragile for a country this big,” Anna Carolina Lobo, a coordinator of the marine program of WWF Brazil, told the Associated Press.

“Brazil has few boats and analysts to follow what happens in our waters.”

Funding for this kind of surveillance is slowing under the leadership of Jair Bolsonaro, Brazil’s far-right president with an aversion to conserving Brazil’s incredibly rich natural environment. Described by his opponents as Captain Chainsaw, he actively encourages the destruction of the Amazon and looks to remove protections for indigenous tribes. Sadly, it seems toxic oil killing helpless sea life is unlikely to top his priorities.