Initial Assessment of Non-Pollen Palynomorphs in a Costa Rican Lake Sediment Core

Keywords: non-pollen palynomorph, spore, fungi, Costa Rica
Session Type: Virtual Poster Abstract
Day: Friday
Session Start / End Time: 2/25/2022 03:40 PM (Eastern Time (US & Canada)) - 2/25/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 49

Abstract

Researchers examining vegetation history based on studying “pollen slides” prepared from lake-sediment cores typically count fern spores as well as pollen grains, and may also count microscopic charcoal fragments. But a wider array of organic microfossils of varied origin are typically found in pollen preparations. Collectively referred to as “Non-Pollen Palynomorphs” or NPP, these understudied microfossils include spores of fungi and hornworts, cyanobacteria, and remains of algae and invertebrates. New research on both temperate and tropical lake sediments over the past decade has shown that NPP can provide new indicators for environmental conditions of the past that are of interest in studies of human-environmental relationships and climate change. Here we describe an initial assessment of NPP in a sediment core from Laguna Santa Elena, a small (0.13 ha) mid-elevation lake in southern Pacific Costa Rica. The core spans ca. 2000 years and shows intervals of prehistoric agriculture during the Aguas Buenas and Chiriquí archaeological periods, population decline before and during the Spanish Conquest, and post-Conquest reforestation, based on prior analyses of pollen, charcoal, and bulk stable isotopes. In this initial assessment of NPP we counted 8 types on pollen slides from 12 levels of the core. Fungal spores of Glomus were the most abundant NPP overall, with peak concentrations at the time of the Spanish Conquest. Myxomycetes cf. Lycogala also peaked at the Conquest, while other NPP showed highest values earlier in the period of prehistoric agriculture (Zygnaemataceae cf. Spirogyra), or during the interval of post-Conquest forest regeration (Basidiosporites).