This is the third in a series of eyewitness reports from Niak Sian Koh, who has been volunteering at a sea turtle conservation project on Tioman Island, in MalaysiaRead Niak’s first field report here and her second field report here.

The sea turtle necropsy was a sobering experience. Learning that the possible root cause of this turtle’s death was marine litter left us a little sick to our stomachs.

Soon, however, we learned of a new problem on the island: Crude oil was washing ashore elsewhere on Tioman Island. Armed with steely motivation, protective gloves, and several large plastic bags, we set off to gather as much of it as we could.

Initially we interns were unsure of what we should be doing. But once at the beach, we quickly realized what the problem looked like: Little, dark-colored pieces of oil, called “tarballs,” covered the entire shoreline of Kampung Juara.

Tarballs on a beach on Tioman Island, Malaysia. Credit: Niak Sian Koh

In February 2016, a large oil spill had occurred in waters near Tioman Island. During the clean-up that followed, the Juara Turtle Project team, marine park officials and local villagers jointly collected more than 700 cement bags of crude oil, which were transported to the mainland to be disposed of. These tarballs might have come from that spill.

How do tarballs form?

When an oil spill occurs in the ocean, the oil spreads into a thin slick that floats on the surface of the water. Wind and waves split this slick into smaller patches and scatters them over a wide area. The mixing of the oil with seawater spurs bio-chemical processes that transform it into a thicker and stickier form, while wind and waves continues to stretch and tear the oil patches into smaller pieces, or tarballs.

Once they reach the beaches, tarballs contaminate the sand, and stick to debris. They never completely disappear naturally, but instead have to be picked up and taken away.

The texture of a tarball is similar to a toasted marshmallow: hard and crusty on the outside, soft and gooey on the inside. They fasten themselves to your shoes as you walk across the beach. Picking one up is a sticky endeavor, because it stubbornly refuses to leave your gloved hands.

Picking up a ball of crude oil on the shoreline of Kampung Juara, Tioman Island, Malaysia. Credit: Niak Sian Koh

During our clean-up work, we found that the larger nuggets of oil were easy enough to collect. But the numerous tiny ones, measuring not more than a few millimeters in diameter, were incredibly difficult.

Struggling against the heat of the tropical midday sun, we raced to pick up as much as we could before the tarballs melted into the sand or washed out again with the tide.

Prevention is the most effective way to avoid the harms of oil spills. But given their unfortunate regularity, governments have developed rules and guidelines for response. The U.S. National Oceanic and Atmospheric Administration has a quick guide to common ways to clean up oil spills on the open sea, such as skimming oil off the top of the ocean surface, onsite burning, and using chemical dispersants to break up the oil into smaller droplets. The most appropriate methods vary depending on factors such as the location of the spill, ocean currents and wind conditions.

Different situations demand different responses to oil spills at sea. Graphic: NOAA

Oil spills have devastating effects on marine ecosystems. Direct contact with the toxic substance causes immediate harm and long-term behavioural changes to marine life.

Sea turtles are particularly susceptible to oil spills, because they can inhale oil when they surface to breathe, and ingest floating tarballs when they mistake them for food. Sea turtles have a habit of ingesting floating objects, which look like one of their favourite snacks: seaweed floating nearby the ocean’s surface.

With every piece of oil and litter we picked up, we thought about the unfortunate green sea turtle back at the JTP headquarters. It was comforting to know that these tarballs and trash would not end up in another turtle’s stomach.