The susceptibility of cladocerans in North Andean-Patagonian lakes to volcanic ashes.

WOLINSKY, L.; LASPOUMADERES, C.; BASTIDAS NAVARRO, M.; MODENUTTI, B.E.; BALSEIRO, E.G.

FRESHWATER BIOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 58 p. 1878 - 1888

0046-5070

1. Explosive volcanic eruptions are one of the few natural phenomena that can produce globalcatastrophic effects. On 4 June 2011, an eruption in the Puyehue volcanic complex (40°35′S, 72°06′W,Chile) discharged massive amounts of ash and pumice into the surrounding landscape in Argentina(North Andean Patagonia). The ejected material affected nearby aquatic environments, producing anincrease in total suspended solids.2. We combined field data and laboratory experiment data to determine the effect of the volcanicashes suspended in the water column on cladoceran populations.3. During the summer of 2011–2012 (6 months after the eruption), zooplankton populations in theselakes decreased, mainly due to the disappearance of cladocerans. This decrease in zooplankton wasnot caused by food shortage; chlorophyll a concentrations in the lakes were higher than in previousyears or in the following season, and no change in phytoplankton size was observed. By the followingsummer (2013), 18 months after the eruption, a recovery of cladoceran populations was observed,with a concomitant decrease in total suspended solids.4. We performed a life-table experiment, examining Daphnia commutata survival and fecundity at aseries of ash concentrations. Ash concentrations of 2, 3, 5 and 8 mg L1 negatively affected survivaland fecundity. Populations exposed to 8 mg L1 of ash cannot persist; these organisms fail toproduce offspring because they die before reaching reproductive age.5. We conclude that the disappearance of cladocerans was due to the presence of ash. As the sedimentationprocess occurs, ash concentrations decrease, favouring population recovery, as observedthe following summer. When the lakes recovered their original transparency with low totalsuspended solids values, the cladoceran populations also returned to their historical abundances.6. Previous data on other explosive volcanic eruptions and the present data indicate that immediatelyafter ash fall, the zooplankton suffer reduced abundance, particularly of non-selective filter feeders suchas daphnids. However, recovery of zooplankton population growth can be expected within a few years.