Why US-Iran war over Hormuz is threatening the Gulf’s waters

The United States-Iran war is increasingly being fought at sea, with both sides targeting oil tankers and other vessels in and around the Strait of Hormuz.

On September 8, the US struck five Iranian oil tankers, provoking an Iranian attack on Jordan’s Al-Azraq airbase.

Just three days earlier, the US also hit three other Iranian tankers. Those strikes came after Iran launched ballistic missiles towards a US aircraft carrier and a navy destroyer near the Strait, according to US Central Command. Iran too subsequently said it had targeted three oil tankers travelling through what it called an “unauthorised route” in the Strait, as well as three US-linked vessels elsewhere.

The tit-for-tat attacks have turned Hormuz into a potential environmental tinderbox. With tankers carrying millions of barrels of crude and petroleum products passing through or waiting around the waterway, a successful strike could trigger a fire, a sinking – or a major oil spill.

As of September 7, MarineTraffic data shows 42 tankers waiting to transit the Strait of Hormuz, while hundreds of other vessels are waiting or moving slowly in the wider Gulf of Oman and Gulf region. Of those tankers, 18 are carrying oil.

While it is not known exactly how much — if any — crude they were carrying, these vessels have an estimated combined capacity to carry 1.76 million cubic metres of oil and petroleum products – cargo that could be at risk if attacks on commercial shipping continue.

That — 1.76 million cubic metres of crude oil — is roughly 11.1 million barrels of oil, and is equivalent to about 11 percent of the world’s daily oil demand.

It is also enough oil to fill roughly 714 Olympic-sized swimming pools.

Now imagine the environmental damage. A major tanker strike or sinking could release millions of litres of oil into the Gulf – potentially contaminating coastlines, fisheries and fragile marine ecosystems.

And unlike an oil spill on land, oil at sea can spread over a vast area, carried by currents and winds far from the original site of the accident.

How many ships have been hit in recent days?

On September 5, US Central Command (CENTCOM) said its forces struck three Iranian crude-oil tankers — one off Kharg Island, Iran’s main oil-export hub; another near Jask; and a third, an unladen tanker, in the Gulf of Oman after its crew was ordered to abandon ship.

The strikes marked a new escalation in attacks on oil shipping in the region.

Since the start of the war, at least 75 ships have been attacked, with at least 21 seafarers killed. Of those vessels, two incidents have resulted in minor oil spills, while six have caused fires.

Oil has been leaking from the Caroline Bezengi since it ran aground about 22 nautical miles (41km) off Oman after its crew reported a suspected explosion in early June. Reuters estimates the tanker was carrying 800,000 barrels of oil.

Oman’s Environment Authority warned that the spill could affect about 40km (25 miles) of coastline near Ras Madraka, as well as Masirah Island.

On August 3, the Minoan Pioneer, a Liberian-flagged bulk carrier, was struck by an unidentified projectile off Oman and caught fire.

Satellite imagery taken on August 10 showed a large slick near Qeshm Island, while another slick was detected near Sirri Island. Experts said the Qeshm slick likely came from the Minoan Pioneer, but could not independently confirm its source.

What is the impact of tankers being attacked on marine life?

Past conflicts like Operation Desert Storm — in which the US fought Iraq after Saddam Hussein’s forces had invaded Kuwait — also left a legacy of environmental pollution.

As Iraqi forces retreated they set Kuwaiti oil wells on fire. These burned for months, and unleashed millions of gallons of oil into the northern Gulf coast which damaged Kuwaiti and Saudi Arabian coastlines for decades.

Over 770km of coastline from southern Kuwait to Abu Ali Island in Saudi Arabia were engulfed in oil and tar, wiping out the local marine ecosystems.

The damage from the oil spill was colossal and destroyed coastline sediments, marine species and ecosystems.

Thirty five years later, the US-Israel war on Iran has once again imperilled the fragile marine ecosystem. US airstrikes have pounded Iranian vessels and oil tankers near the Iranian coast line. Iran has retaliated with similar strikes against ships and tankers from other countries.

The Gulf contains resilient coral reefs and mangrove forests that survive in one of the world’s hottest and most saline marine environments.

The enclosed water is a shallow, semi-enclosed sea supporting coral reefs, seagrass beds, mangroves, mudflats and salt marshes.

These habitats are critical feeding and nursery grounds for fish, turtles, dugongs and migratory birds, while supporting fisheries and protecting coastlines.

With limited water exchange with the wider Indian Ocean, pollution can place added pressure on the Gulf’s marine ecosystems.

A study by the University of South Florida in June stated that based on satellite imagery, the oil spills in Gulf and Strait of Hormuz were four times as much in March than the year before.

The research team noted high instances of oil leaks from vessels trapped in the strait and around trapped vessels.

Oil spills lay on top of the water, and damage and poison marine life, pollute the water, and smother coral reefs and mangroves.

Dr. Hussein Samh al Masroori, Associate Professor at Sultan Qaboos University, speaking to Al Jazeera says that oil and petroleum hydrocarbons can directly affect fish, corals, plankton and other marine organisms. Fish eggs and larvae can be particularly vulnerable.

“Sensitive habitats such as coral reefs, mangroves, seagrass beds and coastal sediments may retain pollutants for much longer,” he says. “There can also be indirect effects through changes in water quality, food-web productivity, fish distribution and potentially spawning or migration patterns. For fisheries, this can translate into reduced fishing opportunities, higher costs and loss of income for coastal communities.”

Oil can also become trapped in sediments, covering beach sand and mud – like in the case of the 1991 oil spill off the Gulf.

Oil spills can smother other marine life, from microscopic plankton and fish larvae to coral reefs, seagrass and mangroves.

The Gulf countries primarily rely on desalination as the primary source of water for the entirety of its nearly 65 million population. Iran also has several desalination plants along its southern coast, some of which have come under attack by the US. There are approximately 15 million people living along the coast of Iran.

Al Masoori explains further that oil contamination near seawater intakes can affect raw-water quality, interfere with treatment processes and, in severe situations, require temporary operational restrictions.

“The actual risk depends greatly on the location of the spill, currents, distance and depth of the intake, and treatment technology.” says al Masroori.

He adds that modern monitoring, modelling and advanced treatment systems can substantially reduce the risk. The priority is early detection so contaminated water can be prevented from entering desalination systems.