Jan 15 (Portal) – A year after a massive eruption from an underwater volcano in the South Pacific, the island nation of Tonga is still grappling with damage to its coastal waters.
When Hunga-Tonga-Hunga Ha’apai blew up, it sent a shockwave around the world, creating a plume of water and ash that shot higher into the atmosphere than any other ever recorded, and triggering tsunami waves that ricocheted across the region – and struck the archipelago lying southeast of Fiji.
Coral reefs were reduced to rubble and many fish died or migrated away.
The result has left Tongans struggling, with more than 80% of Tongan families relying on reef fisheries, according to 2019 World Bank data. After the outbreak, the Tongan government announced it would seek $240 million for recovery, including improving food security. Immediately afterwards, the World Bank provided $8 million.
“Regarding the recovery plan … we are awaiting funding to cover expenses related to small-scale fisheries along coastal communities,” said Poasi Ngaluafe, head of science at the Tonga Ministry of Fisheries.
SILENT REEFS
The vast majority of Tongan territory is ocean, with its exclusive economic zone stretching over nearly 700,000 square kilometers (270,271 sq mi) of water. While commercial fishing contributes only 2.3% to the national economy, subsistence fishing is considered a crucial part of the Tongan diet.
The United Nations’ Food and Agriculture Organization estimated in a November report that the outbreak has cost the country’s fisheries and aquaculture sector about $7.4 million — a significant sum for Tonga’s economy at around $500 million. Losses were largely due to damaged fishing vessels, with almost half of this damage occurring in the small-scale fishing sector, although some merchant vessels were also affected.
Because the Tongan government does not track subsistence fisheries closely, it is difficult to gauge the impact of the outbreak on fisheries harvests.
But scientists say that alongside some fish stocks that are likely to be depleted, there are other worrying signs that the fisheries could be a long time away from recovering.
Young corals are not maturing in the coastal waters around the eruption site, and many areas that were once home to healthy and abundant reefs are now barren, according to the government’s August survey.
It is likely that volcanic ash smothered many reefs, depriving fish of feeding grounds and spawning grounds. The investigation revealed that no marine life had survived near the volcano.
Meanwhile, the tsunami that swelled in the waters surrounding the archipelago knocked over large hard corals and created fields of coral debris. And while some reefs survived, the crackling, snapping and popping sounds of shrimp and fish that are a sign of a healthy environment were gone.
“The reefs in Tonga have been silent,” the survey report said.
AGRICULTURE CALL
Farming has proven to be a lifeline for Tongans faced with empty waters and damaged boats. Despite fears that the volcanic ash covering 99% of the country would make the soil too toxic for cultivation, “food production has resumed with little impact,” said Siosiua Halavatu, a soil scientist speaking on behalf of the Tongan government .
Soil investigations showed that the fallen ash was not harmful to humans. And while yam and sweet potato plants died during the eruption and fruit trees were burned by falling ash, they began to recover after the ash washed away.
“We have supported recovery work through land preparation and planting backyard gardens and root crops on the farms, as well as exporting crops such as watermelons and squashes,” Halavatu told Portal.
But long-term monitoring will be crucial, he said, and Tonga hopes to develop a national soil strategy and improve its soil testing lab to help farmers.
HEAVEN WATER
Scientists are also now taking stock of the eruption’s impact on the atmosphere. While volcanic eruptions on land primarily emit ash and sulfur dioxide, underwater volcanoes eject far more water.
The Tonga eruption was no different: the white-gray plume from the blast reached a height of 57 kilometers (35.4 miles) and spurted 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 overall warming. More atmospheric water vapor can also contribute to the depletion of ozone, which protects the planet from harmful UV radiation.
“This one volcano has 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 beginning to see the impact of that.”
Reporting by Gloria Dickie in London; Additional reporting by Kirsty Needham; Edited by Katy Daigle and Tomasz Janowski
Our standards: The Thomson Portal Trust Principles.