GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreInfluence of the Pacific Decadal Oscillation and El Niño-Southern Oscillation on lacustrine hydroecologic cycling in Alberta
AuteurPatterson, R T; Neville, L A; Gammon, P; Swindles, G T; Macumber, A L
SourceProceedings of PACLIM 2015 - Droughts: Reconstructing the past, monitoring the present, modeling the future. Twenty-Seventh Pacific Climate Workshop; 2015.
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20150266
RéunionPACLIM 2015: Droughts: Reconstructing the past, monitoring the present, modeling the future. Twenty-Seventh Pacific Climate Workshop; Pacific Grove, California; US; mars 8-11, 2015
Documentpublication en série
Lang.anglais
Mediapapier
ProvinceAlberta
Sujetseffets climatiques; assemblages fauniques; Paléolimnologie
ProgrammeDéveloppement durable des sables bitumineux, Géosciences de l'environnement
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
High-resolution (~ 1 yr resolution) temporal variation in Arcellinida (testate lobose amoebae) assemblages and grain-size data were documented in a freeze core record spanning the interval AD 1875-2010 that was collected from Alberta Lake East (ALE). Arcellinidans play a key role in aquatic ecosystems where they exert considerable predatory pressure on bacteria and smaller eucaryotic microbes and represent an important intermediary food web component. In Alberta they respond to nutrient enrichment derived from sediment influxes from the catchment, and provide evidence that lakes in the region exhibit hydroecological responses to temporal variation in precipitation, including droughts. They are thus useful indicators of paleolimnological and climatic change. Anthropogenic influence on this remote kettle lake has been minimal, as there are no roads or other infrastructure within the watershed. PeakFit analysis of the grain size data indicates that the gyttja infill of the lake has not been significantly influenced by bioturbation, despite bottom waters being well oxygenated. Spectral time series analysis of individual arcellinidan taxa (e.g. Cucurbitella triscuspis, a eutrophication indicator), as well as grouped difflugids (generally more sensitive to suboptimal conditions) and centropyxids (opportunistic generalists) resulted in identification of discontinuous cycles archived in the faunal assemblage data, which correlate particularly well with the 2-7-year El Niño-Southern Oscillation (ENSO) and 15-25 and 50-70-year modes of the Pacific Decadal Oscillation (PDO), and to a lesser extent the 50-90-year Atlantic Multidecadal Oscillation (AMO). Wavelet time series analysis of arcellacean assemblages indicate that the hydroecology of ALE changed significantly when the Polar Front retreated northward across the latitude of the lake as the Little Ice Age (LIA) drew to a close. Through the latter stages of the LIA in the late 19th century centropyxids were ecologically dominant and responded strongly to the various climate drivers, particularly ENSO. As ALE warmed and productivity increased through the early 20th century first difflugids and then C. Tricuspis began to out compete the centropyxids, and in turn began to cycle according to the various hydroecological influences of ENSO, PDO and AMO.
Résumé(Résumé en langage clair et simple, non publié)
Les lacs de la région des sables bitumineux montrent des réponses hydroécologiques aux variations temporelles des précipitations, y compris les sécheresses. Les changements dans la réponse hydroecologique se corrèlent particulièrement bien avec les oscillations aux 2 à 7 ans d'El Niño-Sud et avec les modes 15-25 et 50-70 ans des oscillations pacifiques décennales, et dans une moindre mesure aux oscillations multi-décennales atlantiques aux 50-90 ans.
GEOSCAN ID297052