Testate amoebae as non-pollen palynomorphs in pollen slides: usefulness and application in palaeoenvironmental reconstruction

Abstract

Testate amoebae are a frequently used palaeoecological proxy for reconstructing changes in palaeohydrological conditions, particularly in studies of Sphagnum-dominated peatlands. Their use in palaeoecological studies has increased following the development of transfer functions, allowing for the quantitative reconstruction of water-table depth changes through time. Increasingly, they are included in non-pollen palynomorph (NPP) studies alongside a wide range of other proxies, representing a valuable tool, particularly in multi-proxy studies.Testate amoebae have been used for qualitative assessment of palaeohydrology in NPP studies and may aid the verification of environmental interpretations of conditions inferred from curves of NPP with unknown ecology and taxonomy. Their usefulness in such studies is limited by the destruction of tests owing to harsh chemical treatments used in pollen preparation methods. This makes community distribution data of testate amoebae derived by these methods largely unsuitable for quantitative assessment of water-table depth. Furthermore, many palynological studies combine testate amoebae as one single curve, losing further ecological detail. Patterns of change of surviving species, most commonly of Assulina, Archerella, Arcella, Hyalosphenia and Archerella flavum, remain relatively unaffected and therefore can still be useful for interpreting qualitative changes in hydrological conditions through time, particularly when coupled with other proxies.

Fires, Vegetation, and Human—The History of Critical Transitions During the Last 1000 Years in Northeastern Mongolia

“…This is also signaled by a decreased Fe/Mn ratio which indicates the shift toward higher peat oxygenation, and presumably results from the lowering of the ground water level. The disappearance of Triglochin and subsequent occurrence (albeit in low amounts) of Sphagnum, Habrotrocha angusticollis, and Gelasinospora, as well as large numbers of Assulina muscorum shells, support the development of relatively dry habitat on the mire (Andrews et al, 2021;Shumilovskikh et al, 2021;Stivrins et al, 2019;Warner and Chengalath, 1988). An immediate effect of hydrological changes in the mire was accelerated peat decomposition as indicated by the increase in the TOC/TS ratio (Eimers et al, 2003).…”

Microparticles from dental calculus disclose paleoenvironmental and palaeoecological records

“…They appeared circular, with a single central opening in apertural view and a range of diameter equal to 33.4-76 μm (Figure 5o). A similar morphology usually occurs in Arcellinida species, such as Arcella or Galeripora, whose organisms inhabit marshes and other freshwater habitats and whose shells have been found to survive chemical treatments applied for pollen preparation methods (Andrews et al, 2021;González-Miguéns et al, 2022;Payne et al, 2012). However, degraded valves of centric diatoms (e.g., Hyalodiscus species) cannot be excluded as the source of these peculiar microremains (Rott et al, 2009).…”

“…The hypotheses for their presence in dental calculus may be the consumption of: (i) local drinking water (also ephemeral rainwater collected in vessels); (ii) local aquatic food organisms (e.g., fish, shellfish, macroalgae); (iii) dried fish, macroalgae or other seafood collected before reaching the settlement areas neighbouring to Pila cave (e.g., travel to the coast); (iv) mineral concretions (e.g., salt crystals) in which fragments of diatoms may have precipitated. Finally, microparticles referred to as ‘of doubtful origin’ and tentatively attributable to lobose testate amoebae shells and/or degraded diatom frustules, could testify to a wide variety of aquatic and terrestrial environments: lake and river sediments, peat bogs, coastal environments, glaciers and dry mosses growing on different substrates (Andrews et al., 2021; Payne et al., 2012).…”

“…The inclusion of non-dietary microfossils in dental calculus samples, such as silica-rich fragments, has already been documented in the literature. The recovery of such type of remains, including microalto lobose testate amoebae shells and/or degraded diatom frustules, could testify to a wide variety of aquatic and terrestrial environments: lake and river sediments, peat bogs, coastal environments, glaciers and dry mosses growing on different substrates(Andrews et al, 2021;Payne et al, 2012).…”

Why a new volume on non-pollen palynomorphs?

“…It is arranged in three sections. The first contains three background chapters: an overview of what organismal remains are considered NPPs (Shumilovskikh et al 2021), how processing impacts the NPP spectrum obtained by the researcher (Pound et al 2021) (Andrews et al 2021); marine remains including dinoflagellates, acritarchs, tintinnids, ostracod and foraminiferal linings, copepods, and worm remains (Mudie et al 2021). These chapters provide in-depth overviews of the major NPP groups in the context of their occurrence (terrestrial or marine).…”