Attacks by Houthi militants in the Red Sea that have menaced shipping in the vital waterway for months are bringing a new threat — spills that can result in environmental disaster.

The sinking of the Rubymar — loaded with fertilizer and fuel — highlights the potential dangers the conflict poses to some of the world’s largest coral reefs as well as to coastal communities. The Belize-flagged vessel had been taking on water since the mid-February missile strike, which the US said had also caused an 18-mile (29-kilometer) oil slick. The ship went down over the weekend.

Dozens of vessels have been attacked by the Iran-backed Houthis since November, a response to Israel’s war with Hamas in Gaza. The strikes on commercial vessels have continued despite a series of airstrikes by the US and Britain.

While the Rubymar is the first ship that’s been sunk in the Houthi attacks, the frequent launch of missiles toward vessels, including tankers carrying massive amounts of oil, poses the risk of a major accident. The Red Sea is a bio-diversity hot spot with hundreds of reef-building corals and more than a thousand fish species, according to the United Nations. Environmental group Greenpeace warned that a fertilizer spill presented an “imminent danger” to the delicate marine ecosystem.

“This is an area that’s vital for the fishermen of Somalia, Djibouti and Yemen,” said Riad Kahwaji, the Dubai-based head of the Institute for Near East and Gulf Military Analysis. “Any spills of oil or other chemicals can impact livelihoods in these very poor nations with ramifications that are both short-term and long-term.”

On Monday, the International Maritime Organization said it’s working with partners to support the government of Yemen after the sinking of the Rubymar, calling it “an additional risk for the environment and maritime security.”

“To mitigate the environmental risks in the Red Sea region, policymakers must prioritize efforts to reduce tensions and instability in the region,” said Julien Jreissati, program director for Greenpeace MENA.