Understanding Tobago’s disastrous oil spill

Originally published on Global Voices

An aerial view of Tobago’s oil spill. Photo courtesy of the Office of the Chief Secretary, Tobago House of Assembly.

By Jeniece Germain

This post was first published on the Cari-Bois Environmental News Network; the version below is republished as part of a content-sharing agreement.

Authorities in Tobago are continuing an investigation into the circumstances surrounding a disastrous oil spill which occurred approximately 150 kilometres (93 miles) off the island’s southern coast on February 7.

In a media release, the Ministry of National Security noted that preliminary investigations revealed that two vessels — a barge named “Gulfstream” and a tugboat — were involved in the incident.

The Gulfstream, which is presumed to have been en route from Panama to Guyana, has thus far been identified as the boat which overturned and caused the spill, but the whereabouts of the tugboat are currently unknown.

This latest spill comes in the wake of several other spills which occurred in Trinidad and Tobago (both inland and offshore) over the past several years, including the 2020 “Nabarima” incident, in which there were concerns that a sinking oil tanker in the Gulf of Paria could pose a threat of an oil spill.

While Trinidad and Tobago's National Oil Spill Contingency Plan was triggered with immediate effect for the latest spill, the director of the Tobago Emergency Management Agency (TEMA), Allan Stewart, said there was initial difficulty in obtaining logistical support.

TEMA has been leading the cleanup efforts and is being assisted by its Community Emergency Response Team (CERT), which has over 1,000 members. Their efforts have also been supported by the Ministry of Energy and the Tobago House of Assembly’s (THA) Division of Infrastructure, Quarries, and Urban Development. Other organisations assisting with the efforts include the Institute of Marine Affairs (IMA), the Trinidad and Tobago Coast Guard, Heritage Petroleum, Oil Mop Environmental Services and Tiger Tanks Company.

The extent of the spill and its effects

Preliminary assessments by the IMA have shown that the affected areas include Cove Reef, Kilgwyn Bay, Canoe Bay, Petit Trou Lagoon, Upper Lambeau Beach, Middle Lambeau, and Topaz Beach.

The spill’s effects on the Petit Trou Lagoon, located on the coast of Lowlands, Tobago, has caused utmost concern, given the area is ecologically sensitive with dense mangrove cover and is also a popular tourist site because of its boardwalk, which runs through the mangroves. In the last two years alone, there has been a noticeable mangrove die-off in the lagoon, which has left it more susceptible to environmental hazards like the oil spill.

Currently, the IMA is focusing its efforts on analysing samples from Petit Trou and other selected areas, to monitor changes in hydrocarbon concentrations (indicative of oil) in comparison with pre-spill conditions. The effects of an oil spill can be detrimental to marine life and human livelihoods because of the ease by which oil can be dispersed and its toxicity.

At sea, oil predominantly stays on the surface and can be easily spread by winds and currents, which can entrap birds and other animals. If mixed with sand due to wave action, oil may sink and can affect sea-floor communities like coral reefs and sea grasses, which can result in mortality or impaired growth and reproduction.

On land, the problem is exacerbated. In structurally complex systems like mangroves, oil can smother roots and combine with sediment, making it difficult to remove. Fumes from oil may also cause respiratory damage if inhaled and poison organisms if ingested, which in turn can affect human health if consumed. Given the potential effects associated with the spill, the THA and the IMA have strongly advised against the collection, sale and consumption of fish from affected areas.

In conjunction with any potential effects on tourism, this may have some impact on Tobago’s economy since tourism accounts for 25 percent of employment on the island. However, authorities have not yet made statements regarding the costs of damages associated with the spill.

How can sargassum impact the spill’s effects?

Image of sargassum via Canva Pro.

As Tobago contends with the spill, its coasts are simultaneously experiencing an influx of sargassum — a macroalgae that, like oil, floats at the water’s surface. While adrift, sargassum can form extensive “mats,” spanning kilometres, which are used as the habitat for sargassum fish and other juvenile or small organisms.

While the management of these “golden tides” of sargassum in the region has improved in recent times, it is uncertain whether the combination of the interaction of oil and sargassum is harmful or provides some benefit to coastal ecosystems.

According to the National Oceanic and Atmospheric Administration (NOAA), the mixing of sargassum with oil may cause the oil to sink and negatively affect organisms on the seafloor, but it might be possible that sargassum has some benefit in protecting the coast in the face of oil spills.

Images released by TEMA have revealed oil mixing with, and being impeded by, large mats of sargassum that had been previously washed ashore, preventing the oil from moving further onto the beach.

In a brief interview with a volunteer working at the spill site who didn’t want to be identified, we learnt that clean-up efforts alongside sargassum proved to be quite effective as the foliage was able to “catch” the oil, allowing it to be collected more easily. Though sargassum only occurred at a few of the affected beaches, this presents an opportunity for further investigation.

Current status of the spill and clean-up efforts

By February 13, six days after the spill, TEMA had made noticeable progress in removing oil from the waters of Rockly Bay, Scarborough, and containing the spill using a floating barrier called a boom — but up to that time, divers were unable to stop the leak at its source because of turbulent waters and limited visibility.

The extent and continuous nature of the spill have the emergency ranked at Level Two (orange) status, which requires national assistance. The slick has since been observed extending as far as 144 kilometres (89 miles) west of Tobago.

Although this can negatively affect marine life as far as the territorial waters of Grenada, it currently poses no immediate threat to the country’s coasts. However, the spill may potentially reach Venezuela and trigger actions under the Bilateral Oil Spill Contingency Plan (1989) between Trinidad and Tobago and Venezuela.

Originally published in Global Voices.