The eruption of Chile’s 6,500-foot Calbuco volcano on April 22 blacked out the sun and rained down 20 inches of ash—enough to collapse the roofs of homes in the nearby town of Ensenada. The ash cloud, carried by winds out of the southwest, darkened the skies above Buenos Aires, almost 1,000 miles away.
In the immediate aftermath, more than 6,000 people from Ensenada, Chamiza, Lago Chapo, and Correntoso were evacuated, according to the AP. One local resident told Reuters that his town had an “Armageddon-type reaction.” Chile’s National Geologic and Mineral Service is keeping the area around Calbuco under red alert, as the volcano could erupt again at any time.
As attention shifts away from the disaster relief, many people have expressed concern about the region’s world-class fishing and hunting opportunities. Could Patagonia, one of the adventure capitals of the world, suffer any major ecological disruptions? To understand the potential impact, it’s worth examining the fallout from the much larger eruption, in 2011, of Puyehue-Cordón Caulle, a stratovolcano roughly 40 miles north of Calbuco that deposited 100 million tons of ash in Chile and Argentina.
According to experts, the eruption will affect the surrounding environment, but only temporarily. Ash itself is inert, according to Tom Casadevall, a United States Geological Survey volcanologist in Denver. But it will pick up chemicals like sulfur, chloride, and fluoride from the atmosphere before falling back to terra firma. “People get very concerned that these are in toxic quantities, but they’re not,” says Casadevall, who was in San Carlos de Bariloche (an Argentinian city near the Chile border) at the time of the April 22 eruption. “They’re a nuisance, but with the first rain or any hint of moisture, those absorbed elements will wash off and be diluted by the rainfall.” [sic, see excerpt from a 2015 report by the European Science Foundation at the end of this article]
Even though the chemicals may be diluted, the ash being swept into the water can still have a dramatic impact by clogging the gills and intestines of fish that eat ash particles and, in some cases, by damming up whole streams. Official estimates aren’t available yet, but National Fisheries Service regional director Eduardo Aguilera told the AP in the days after the eruption that 20 million fish have died.
Cameron Chambers, who was fishing in Argentina when Calbuco blew and researched the 2011 eruption’s impact on fisheries for a chapter in his book, Chasing Rumor: A Season Fly Fishing in Patagonia, doesn’t think that the effects will be that extreme. “The fish population seems to be doing just fine,” says Chambers, adding that Chile’s wildlife monitoring isn’t accurate. “It’s very unlikely that [this eruption] is going to have too detrimental an effect on the fish.” The more severe Puyehue eruption reportedly only killed 4.5 million fish, and a 2014 study by the Argentina Association of Ecology found that streams were quick to recover.
Terrestrial wildlife in the region—like red deer and boar—will fare better, says Casadevall. Most wild animals can simply migrate away from the area affected by the ash fall. However, one 2014 study on Puyehue’s effects from Argentina’s National Council of Scientific and Technological Research found that red deer in areas of the country where rain hadn’t washed away the ash suffered loss of teeth and fluoride poisoning. But a 1994 study from the National University of Patagonia examining the effects of the 1991 Volcán Hudson eruption found that many mammal populations, like hare and guanaco, were bouncing back within 18 months. So hunting could be slim pickings for the next year and a half, but it should pick up as wildlife migrate back and repopulate.
After Puyehue, staff in Argentina’s Jacobacci municipality estimated that up to 60 percent of a 285,000-large herd of sheep and goats died due to teeth abrasion, starvation, dehydration, and stomach blockages. “Ranchers had to move or sell their livestock or else all would have perished during that winter with no grass,” says Alberto Cordero, a guide based out of San Martin de los Andes, Argentina.
All is not gloom and doom, though. With short-term exposure, volcanic ash can boost the land’s productivity. “There’s lots of evidence that shows that these soluble volcanic gases, when added to soil, do have a fertilizer effect,” Casadevall says. “Mount St. Helens had record apple and fruit harvests following its 1980 eruption. Wildlife will come right back.”
The eruption of Laki in Iceland in 1783 caused about 9,350 deaths in Iceland. Although there was little direct impact, the eight-month emission of sulfuric aerosols resulted in a large distribution of the ash cloud (Figure 14) causing one of the most important climatic and socially repercussive events of the last millennium. The consequences for Iceland – known as the Mist Hardships – were catastrophic. An estimated 20–25% of the population died in the famine and from fluorine poisoning after the fissure eruptions ceased. Around 80% of sheep, 50% of cattle, and 50% of horses died because of dental and skeletal fluorosis from the 8 million tons of hydrogen fluoride that were released…