Browsing by Autor "Bronwen Konecky"

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Subseasonal Variations of Stable Isotopes in Tropical Andean Precipitation
(American Meteorological Society, 2019) Heather Guy; Anton Seimon; L. Baker Perry; Bronwen Konecky; Maxwell Rado; Marcos Andrade; Mariusz Potocki; Paul A. Mayewski
Abstract The tropical Andes of southern Peru and northern Bolivia have several major mountain summits suitable for ice core paleoclimatic investigations. However, incomplete understanding of the controls on the isotopic (δD, δ18O) composition of precipitation and a paucity of field observations in this region continue to limit ice-core-based paleoclimate reconstructions. This study examines four years of daily observations of δD and δ18O in precipitation from a citizen scientist network on the northeastern margin of the Altiplano, to identify controls on the subseasonal spatiotemporal variability in δ18O during the wet season (November–April). These data provide new insights into modern δ18O variability at high spatial and temporal scales. We identify a regionally coherent subseasonal signal in precipitation δ18O featuring alternating periods of high and low δ18O of 9–27-day duration. This signal reflects variability in precipitation delivery driven by synoptic conditions and closely relates to variations in the strength of the South American low-level jet and moisture availability over the study area. The annual layer of snowpack on the Quelccaya Ice Cap observed in the subsequent dry season retains this subseasonal signal, allowing the development of a snow-pit age model based on precipitation δ18O measurements, and demonstrating how synoptic variability is transmitted from the atmosphere to mountaintop snowpacks along the Altiplano’s eastern margin. This result improves our understanding of the hydrometeorological processes governing δ18O and δD in tropical Andean precipitation and has implications for improving paleoclimate reconstructions from tropical Andean ice cores and other paleoclimate records.
Upward range extension of Andean anurans and chytridiomycosis to extreme elevations in response to tropical deglaciation
(Wiley, 2006) Tracie A. Seimon; Anton Seimon; Peter Daszak; Stephan Halloy; Lisa M. Schloegel; César Aguilar; Preston Sowell; Alex D. Hyatt; Bronwen Konecky; John Simmons
Abstract High‐alpine life forms and ecosystems exist at the limits of habitable environments, and thus, are especially sensitive to environmental change. Here we report a recent increase in the elevational limit of anurans following glacial retreat in the tropical Peruvian Andes. Three species have colonized ponds in recently deglaciated terrain at new record elevations for amphibians worldwide (5244–5400 m). Two of these species were also found to be infected with Batrachochytrium dendrobatidis ( Bd ), an emerging fungal pathogen causally associated with global amphibian declines, including the disappearance of several Latin American species. The presence of this pathogen was associated with elevated mortality rates of at least one species. These results represent the first evidence of upward expansion of anurans to newly available habitat brought about by recent deglaciation. Furthermore, the large increase in the upper limit of known Bd infections, previously reported as 4112 m in Ecuador, to 5348 m in this study, also expands the spatial domain of potential Bd pathogenicity to encompass virtually all high elevation anuran habitats in the tropical Andes.