Contribution of non-pollen palynomorphs to the paleolimnological study of a high-altitude Andean lake (Laguna Verde Alta,Venezuela) |
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| Authors: | Valentí Rull José A López-Sáez Teresa Vegas-Vilarrúbia |
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| Institution: | (1) Departament de Biologia Animal, Biologia Vegetal i Ecologia, Facultat de Biociències, Universitat Autònoma de Barcelona, C1-215/227, Bellaterra, 08193 Barcelona, Spain;(2) Departamento de Prehistoria, Consejo Superior de Investigaciones Científicas, Instituto de Historia, Duque de Medinaceli 6, 28014 Madrid, Spain;(3) Departament d’Ecologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain |
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| Abstract: | This paper evaluates the potential usefulness of non-pollen palynomorphs or NPPs (microfossils other than pollen and spores
present in palynological preparations) contained in lake sediments in the paleolimnological reconstruction of high altitude
environments (>4,000 m) from the Venezuelan Andes. A synthetic, quantitative approach is employed, instead of the classical
analytical and mostly qualitative approach commonly used so far for NPPs. The main sources of variation are the Pediastrum–Botryococcus alternation and the relationship between these two algae and animal remains such as Acari legs, postabdomina of Cladocera,
mandibles of other invertebrates, and an unknown type called LVA-1. Other significant microfossils are remains of Rivularia-type and turbellarian oocytes, including Gyratrix. The sequence initiates around 15,000 calibrated years before present (cal BP) with the deglaciation of the lake catchment,
high water levels and still cold climates. A phase of lower lake levels was recorded between about 12,000 and 6,000 cal BP.
Temperatures increased by around 9,000 and 7,000 cal BP, and then decreased until 6,000 cal BP. Since that time, both lake
levels and temperature increased again and stabilized at about 4,000 cal BP, when they reach modern-like values. These results
show a good agreement with previous studies based on pollen, diatom and oxygen isotope analyses, and provide additional paleoecological
information, as for example the possibility of a previously unrecorded Younger Dryas signal. The inclusion of quantitative
NPP analysis in routine paleolimnological studies using synthetic methods is thus recommended. Possible future improvements
are suggested, mainly those related with the development and use of NPP modern analogs. |
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| Keywords: | Palynology Non-pollen palynomorphs Late-Glacial Holocene Venezuelan Andes High altitude |
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