Impact of Chaitén Volcano ashfall on native and exotic fish recovery, recolonization, and abundance

DI PRINZIO C; GRECH MARTA; MANZO LUZ; MISERENDINO L.; CASAUX R,

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021 vol. 752

0048-9697

The effects of volcanic disturbance on aquatic communities and their recovery are poorly studied. To fill this gap,we explored the effects on fish communities in rivers in Argentina of the 2008 eruption of Chaitén Volcano insouthern Chile (42.8° lat. S). The eruption produced volcanic plumes of ash that persisted in the atmospherefor several months. Borne on westerly winds, deposits of tephra crossed the Andes Mountains, reaching the Atlanticcoast (Argentina). We compared the pre- and post-eruption abundances of a native catfish Hatcheriamacraei, and two introduced trout from rivers covered by the volcanic plumes (Argentina) using Before-After-Control-Impact analysis to explore fish recovery. Total suspended solids fromvolcanic ashfall, macroinvertebrateabundance and richness, and species ecological attributes influenced the spatial arrangement of fish in rivers.Twenty-one months after the eruption, Rainbow Trout, Oncorhynchus mykiss, had not returned to pre-eruptionabundances in the sampled rivers, and only four rivers had regained pre-eruption species composition, suggestingthat disturbance is still ongoing. The abundance of introduced fishes was strongly, negatively correlatedwithTSS, suggesting that ashfall affected these fish probably by clogging and abrasion of the gills. Fish recolonized previouslyoccupied habitats 4 days to 9 months after the disturbance. Hatcheria macraei was the slowest to recolonize,whereas O. mykiss were the pioneer fish in 4 rivers following the eruption and recolonized all 5 riverswherethey were present prior to the eruption. In one river, the catfish and the Brown Trout, Salmo trutta, were still absent21months post-eruption, potentially owing to the lack of riparian cover thatwould have deflected the entryof ash. Rainbow Trout suffered significant declines in abundance,whereas Brown Trout and catfish generally didnot, owing to their ecological attributes. Total fish abundance was negatively correlated with ash thickness, butpositively related to prey availability.