Tongas massive underwater volcanic eruption https://www.reuters.com/business/environment/impact-assessment-aid-efforts-underway-world-responds-tonga-tsunami-2022-01-16 could deliver long-lasting damage to coral reefs, erode coastlines and disrupt fisheries, say scientists studying satellite images and looking to the past to project the future of the remote region:
ACID RAIN Since the eruption, the volcano has been releasing sulfur oxide and nitrogen oxide gases. These gases are known to cause acid rain when they react with water and oxygen in surrounding atmospheres.
According to Shane Cronin, University of Auckland volcanologist, acid rain is likely to continue in Tonga’s tropical climate. Acid rain can cause widespread crop damage and could lead to the destruction of Tongan staples such as taro, corn and bananas. Cronin stated that food security could be compromised depending on how long the eruptions continue.
Satellite imagery shows that the plume is spreading westward. This could mean that Tonga could be spared some acid rainfall, but Fiji could then be in its path. The U.N. humanitarian affairs bureau stated that Fiji was monitoring the air quality and advised people to keep their water tanks covered and to stay indoors in case of rain.
FISH DIE OFFS Tongas is home to an exclusive economic zone that covers nearly 700,000 km (270,271 sq miles) which is 1,000 times more than its land. Tongans rely on the ocean for their livelihood and food.
Marco Brenna, a New Zealand geologist, said that scientists have yet to investigate the area. However, the few photos that are available seem like it shows a blanket of ash covering the land. This ash can cause damage to marine life in the ocean. Weeks before Saturdays eruption, Tonga Geological Services had warned https://matangitonga.to/2022/01/04/toxic-seawater-at-hunga-volcano-may-poison-fish that nearby seawater was contaminated with toxic volcanic discharge, and that fishermen should assume fish in these waters are poisoned or poisonous.
The situation has only gotten worse with every eruption. The volcano’s ash-rich water will contaminate the river and kill fish. Scientists predict that some fish will die and survivors will have to migrate. Additional changes in the sea floor structure could pose new challenges for fishing vessels. Brenna stated that it will take some time before the existing or new fishing grounds can be restored.
SMOTHERED COLORS Falling ash can also cause coral reefs to be smothered. These coral reefs were the mainstay of Tonga’s tourist industry, which brought in as much as $5 million per annum before the coronavirus epidemic.
Tongas reefs were under threat from disease outbreaks, climate change and increasing cyclones. Now, vast areas of the reefs in the immediate impact area at Hunga Tonga are probably buried and smothered by large deposits of volcanic ash, said Tom Schils, a marine biologist at the University of Guam who has studied https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0046639 volcanic eruptions and corals in the Northern Mariana Islands.
These eruptions can also release more iron into water, which can increase the growth of blue-green alga and sponges, which further degrades reefs. Brian Zgliczynski is a coral reef ecologist at Scripps Institution of Oceanography. He said that the process of rebuilding reefs could take several years. He said that species that are more tolerant to poor water quality will be the first to arrive, while hard corals or fish will take longer to return.
ERODED COASTLINES Tonga’s ability and ability to withstand rising waters and storm surges would also be affected by the loss of coral reefs. This is a concern in Tonga where climate change is driving sea level rise by 6 millimeters (0.2 inch) per year, twice the global average.
In a 2015 report https://www.researchgate.net/profile/Leanne-Fernandes/publication/317341776_National_marine_ecosystem_service_valuation_summary_Tonga/links/5bbe5828299bf1010178adac/National-marine-ecosystem-service-valuation-summary-Tonga.pdf, Tonga valued its natural storm buffers including coral reefs as well as coastal seagrasses and mangroves at some $11 million annually. A Tongan sea-level gauge recorded a tsunami wave measuring 1.19 metres (nearly 4 feet) at the time of the latest eruption. It then stopped reporting. Tsunamis can cause coastal erosion. Video footage showed damage to manmade seawalls, even before the Internet was down.
Cronin stated that the tsunami waves could impact coastal defenses and reclaimed land, making the islands more vulnerable.
(This story is not edited by Devdiscourse staff.