Total devastation of river macroinvertebrates following a volcanic eruption in southern Chile

Abstract

Although explosive volcanic eruptions are natural disturbances that cause significant environmental repercussions and impose multiple changes on ecosystems, post-eruption studies of rivers and streams are not common. The most recent eruption of the Puyehue-Cord on Caulle volcanic complex (PCCVC) began on 4 June 2011 with a large explosion and the emission of a column of gas and volcanic ash (particle size <0.001-2 mm) followed by the release of silica magma, and lasted approximately until June 2012. The wind-dispersed volcanic ash affected the area surrounding the PCCVC in southern Chile and, subsequently, most of South America, but local effects on streams and rivers in the vicinity were more drastic. We collected water, ash, and benthic macroinvertebrate samples four months after the eruption from four rivers: Two were visibly impacted (Gol-Gol and Nilahue) in areas where volcanic ash thickness ranged between 1 and 5 cm, in the vicinity of the PCCVC fissure (8-15 km), and two adjacent rivers (Calcurrupe and Chanleufu) were located 20-40 km from the PCCVC fissure where ash thickness was <1 cm and did not present visible impacts. Results were then compared with data obtained from previous research projects. This study reports that this natural disaster induced an increase in concentrations of total suspended solids and of phosphorous in the rivers Gol-Gol and Nilahue, as well as habitat destruction, deterioration of environmental quality, and the consequent devastation of macroinvertebrate assemblages inhabiting these rivers directly following the eruption. We conclude that volcanic eruptions can generate local extinctions of benthic macroinvertebrates in the short term, compared with rivers that were not affected by volcanic ash.

Recovery after volcanic ash deposition: vegetation effects on soil organic carbon, soil structure and infiltration rates

“…However, farming on volcanic slopes and adjacent valleys also involves exposure to extreme circumstances during volcanic eruptions. This includes pyroclastic materials deposition of < 2 mm tephra fractions (it includes sand, silt and clay particles in conventional texture analysis) which is often directly referred to as 'volcanic ash' (Arnalds 2013;Fuentes et al 2020;Müller et al 2019;Rossi et al 2021;Suh et al 2019), and subsequent volcanic ash movement in the landscape (Anda et al 2016;Ayris and Delmelle 2012;Zobel and Antos 2017). Parts of the literature on volcanic soils describes long-term soil genesis (Babiera and Takahashi 1997;Dahlgren and Ugolini 1989;Fiantis et al 2021;Fiantis et al 2017;James et al 2016;Ontiveros et al 2016;Schlesinger et al 1998).…”

Impacts of volcanic eruptions and early recovery in freshwater environments and organisms

“…Community structure and function may be affected in a variety of ways (Table 1). In some cases, these modifications can lead to the death of all organisms (total destruction) (Janda et al, 1981;Larson, 1993;Fuentes et al, 2020), or may promote the growth of other organisms (due to the generation of new niches, temporary disturbance) (Eicher & Rounsefell, 1957;Frenzel, 1983;Lucas & Weinheimer, 2005). The impact on ecosystems depends largely on the type of disturbances generated by the eruption and also on pre-eruption conditions.…”

“…In stream benthos, an increase in suspended and deposited solids of any origin can modify community structure, from a community dominated by Ephemeroptera, Plecoptera and Trichoptera (EPT) to one dominated by Oligochaeta, Chironomidae and Bivalvia, taxa adapted to burial (Wood & Armitage, 1997). In extremely severe cases, total destruction of the benthic fauna can occur, as was recorded in streams very close to the PCCVC 2011 eruption (Fuentes et al, 2020). In general, simple habitats are associated with lower species diversity than complex habitats.…”

An analysis of volcanic SO2 and ash emissions from Copahue volcano

“…The eruption of the Puyehue-Cordón Caulle volcanic complex in June 2011 (40 • 30 ′ S-72 • 12 ′ W) affected areas surrounding the volcanic complex in southern Chile and the Patagonian steppe (Wilson et al, 2013;Elissondo et al, 2016). This eruption dispersed pyroclastic material until June 2012, which devastated river macro-invertebrates (Fuentes et al, 2020), caused the death of grazing animals and the interruption of basic services -e.g., water, electric power, wastewater treatment, among others- (Wilson et al, 2013). Bubach et al (2014Bubach et al ( , 2020 evaluated the concentration of sulfur, selenium and heavy metals in lichens, to determine the atmospheric pollution associated with volcanic activity in the Southern Andean Volcanic zone (SVZ) (volcanic complexes Copahue-Caviahue and Puyehue--Cordón-Caulle).…”