Paleolimnological responses of Ecuadorian páramo lakes to local and regional stressors over the last two millennia

Autor: Melina Luethje, Xavier Benito, Tobias Schneider, Pablo V. Mosquera, Paul Baker, Sherilyn C. Fritz
Přispěvatelé: Producció Animal, Aigües Marines i Continentals
Rok vydání: 2023
Předmět:
Zdroj: Journal of Paleolimnology. 69:305-323
ISSN: 1573-0417
0921-2728
DOI: 10.1007/s10933-022-00274-5
Popis: Increasing surface air temperatures and human influences (e.g., agriculture, livestock grazing, tourism) are altering lacustrine ecosystems in the South American Andean páramo, and these influences are evident in changes in the diatom-species composition in sediment cores from the region that span the last ~ 150 years. Existing studies are limited by their short temporal scales and limited spatial extent. We analyzed two sediment cores spanning the last two millennia from the northern (Laguna Piñan) and southern (Laguna Fondococha) Andean páramo of Ecuador to provide a longer-term perspective on lake dynamics. Both lakes show shifts in the dominant diatoms through time. Fondococha diatoms shifted in dominance between two Aulacoseira species and in the planktic to benthic ratio, and these shifts are interpreted as evidence of changing lake level. The inferred shifts are corroborated by changes in sediment geochemistry. Piñan shows a directional shift in the diatom assemblage over the period of the record, from benthic diatoms tolerant of high dissolved organic carbon (DOC), low pH, and low nutrients, to an assemblage characteristic of lower DOC, higher pH, nutrients and lake levels. Shifts in Piñan’s diatoms are correlated with tephra layers in the sediment, suggesting that local volcanic deposition may have been responsible for altering the catchment and lake geochemistry. This is supported by relatively high δ13C values in organic matter associated with tephra layers, which become more negative up-section. Our study suggests that remote lakes in spatially heterogenous montane regions act as sentinels of different facets of environmental change and provide insights into Andean ecosystem responses to environmental perturbations. info:eu-repo/semantics/acceptedVersion
Databáze: OpenAIRE
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