A year after the volcanic eruption, many of Tonga’s coral reefs remain silent

Jan. 15 (Reuters) – A year after the massive eruption of an underwater volcano in the South Pacific, the island of Tonga is still dealing with damage to its coastal waters.

When Hunga-Tonga-Hunga Ha’apai exploded, I sent a Earthquake around the world column of water and ash that rose higher into the atmosphere than anything else on record, and triggered tsunamis that bounced across the region – and crashed into the archipelago that lies southeast of Fiji.

The coral reefs were reduced to rubble and many fish died or migrated away.

The disaster worsened conditions for Tonga’s population, more than 80% of whom were already dependent on reef fishing, according to 2019 World Bank data. After the eruption, the Tongan government said it would seek $240 million for recovery, including improvements Food security. In the immediate aftermath, the World Bank provided $8 million.

“In terms of the recovery plan…we are waiting for funds to cover expenses associated with small-scale fisheries along the coastal communities,” said Buasi Ngalwaf, head of science at Tonga’s Ministry of Fisheries.

Silent Reef

The vast majority of Tonga’s territory is ocean, with its exclusive economic zone stretching across nearly 700,000 square kilometers (270,271 sq mi) of water. While commercial fisheries contribute only 2.3% to the national economy, subsistence fishing is crucial to making up a staple of the Tongan diet.

The Food and Agriculture Organization of the United Nations estimated in a November report that the volcanic eruption had cost the country’s fisheries and aquaculture sector some $7.4 million — a significant figure for Tonga’s nearly $500 million economy. The losses were largely attributed to the destruction of fishing vessels, with about half of this damage in the small-scale fisheries sector, although some commercial vessels were also damaged.

Since the Tongan government does not track subsistence fishing closely, it is difficult to estimate the impact of the eruption on fish harvests.

But scientists say that aside from the possible depletion of some fish stocks, there are other worrying signs that fisheries could take a long time to recover.

Young corals fail to mature in the coastal waters around the eruption site, and many areas once home to healthy and plentiful corals are now barren, according to a government survey in August.

The volcanic ash likely suffocated many of the reefs, depriving the fish of their feeding grounds and breeding grounds. The survey found that no marine life had survived near the volcano.

Meanwhile, the tsunami that swelled in the waters surrounding the archipelago struck large, stony coral reefs, creating fields of coral rubble. And while some corals survived, the crackling, snapping and clattering sounds of foraging for shrimp and fish, a sign of a healthy environment, disappeared.

The survey report found that “Tonga’s coral reefs were silent”.

giving up agriculture

Farming has proven to be a lifeline for Tongaans facing empty waters and damaged boats. Despite concerns that the volcanic ash, which has covered 99% of the country, would make the soil too toxic for growing crops, “food production has resumed with minimal impacts,” said Seusio Halafato, a soil scientist speaking on behalf of the Tonga government.

Soil tests revealed that the fallen ash was not harmful to humans. And while yams and sweet potatoes died during the eruption, and fruit trees were burned by falling ash, they began to recover once the ash was washed away.

“We have supported recovery work by preparing the land, planting back gardens and root crops on farms as well as exporting crops such as melons and pumpkins,” Halavato told Reuters.

But he said long-term monitoring will be crucial, and Tonga hopes to develop a national soil strategy and upgrade a soil testing laboratory to help farmers.

sky water

Scientists are also now assessing the eruption’s impact on the atmosphere. While volcanic eruptions on land spew out mostly ash and sulfur dioxide, underwater volcanoes spew more water.

The Tonga eruption was no different, with the grayish-white plume reaching 57 kilometers (35.4 miles) across and pumping 146 million tons of water into the atmosphere.

Water vapor can remain in the atmosphere for up to a decade, trapping heat at the Earth’s surface and leading to more global warming. More water vapor in the atmosphere could also help deplete the ozone layer, which protects the planet from harmful UV rays.

“This one volcano increased the total amount of global water in the stratosphere by 10 percent,” said Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center. “We’re only now starting to see the impact of that.”

(This story has been corrected to fix a word in the title and timeline in the fourth paragraph)

(Reporting by Gloria Dickey in London). Additional reporting by Kirsty Needham. Editing by Katie Daigle and Thomas Janowski

Our standards: Thomson Reuters Trust Principles.