scholarly journals Comparing and improving methods for reconstructing peatland water-table depth from testate amoebae

The Holocene ◽  
2019 ◽  
Vol 29 (8) ◽  
pp. 1350-1361
Author(s):  
Connor Nolan ◽  
John Tipton ◽  
Robert K Booth ◽  
Mevin B Hooten ◽  
Stephen T Jackson
Keyword(s):  
Water Table ◽  
Compositional Data ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
Weighted Averaging ◽  
Training Dataset ◽  
Testate Amoeba ◽  
Test Case ◽  
Ecological Communities ◽  
Validation Experiment

Proxies that use changes in the composition of ecological communities to reconstruct temporal changes in an environmental covariate are commonly used in paleoclimatology and paleolimnology. Existing methods, such as weighted averaging and modern analog technique, relate compositional data to the covariate in very simple ways, and different methods are seldom compared systematically. We present a new Bayesian model that better represents the underlying data and the complexity in the relationships between species’ abundances and a paleoenvironmental covariate. Using testate amoeba–based reconstructions of water-table depth as a test case, we systematically compare new and existing models in a cross-validation experiment on a large training dataset from North America. We then apply the different models to a new 7500-year record of testate amoeba assemblages from Caribou Bog in Maine and compare the resulting water-table depth reconstructions. We find that Bayesian models represent an improvement over existing methods in three key ways: more complete use of the underlying compositional data, full and meaningful treatment of uncertainty, and clear paths toward methodological improvements. Furthermore, we highlight how developing and systematically comparing methods lead to an improved understanding of the proxy system. This paper focuses on testate amoebae and water-table depth, but the framework and ideas are widely applicable to other proxies based on compositional data.

scholarly journals Ecology of peatland testate amoebae in Svalbard and the development of transfer functions for reconstructing past water-table depth and pH

2021 ◽  
Vol 131 ◽  
pp. 108122
Author(s):  
Thomas G. Sim ◽  
Graeme T. Swindles ◽  
Paul J. Morris ◽  
Andy J. Baird ◽  
Dan J. Charman ◽  
...  
Keyword(s):  
Water Table ◽  
Transfer Functions ◽  
Testate Amoebae ◽  
Water Table Depth

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

2020 ◽  
pp. SP511-2020-34
Author(s):  
L. O. Andrews ◽  
R. J. Payne ◽  
G. T. Swindles
Keyword(s):  
Water Table ◽  
Transfer Functions ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
Qualitative Assessment ◽  
Distribution Data ◽  
Preparation Methods ◽  
Chemical Treatments ◽  
Wide Range ◽  
Qualitative Changes

AbstractTestate 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.

Do the relationships between testate amoebae and fungi reflect the variability of past water table fluctuations in the ombrotrophic peatlands of Central Europe?

The Holocene ◽  
2020 ◽  
Vol 30 (8) ◽  
pp. 1186-1195
Author(s):  
Piotr Kołaczek ◽  
Monika Karpińska-Kołaczek ◽  
Mariusz Gałka ◽  
Grażyna Miotk-Szpiganowicz ◽  
Milena Obremska ◽  
...  
Keyword(s):  
Central Europe ◽  
Water Table ◽  
Pollen Analysis ◽  
Calluna Vulgaris ◽  
Testate Amoebae ◽  
Cold Climate ◽  
Testate Amoeba ◽  
Additional Information ◽  
Sphagnum Peat ◽  
Climate Events

In this article, we examined the indicative value of a relationship between two non-pollen palynomorphs (NPPs), fungal HdV-10, related to the presence of Calluna vulgaris, and HdV-31A, which is testate amoeba – Archerella flavum. Both are frequently present on slides designated for pollen analysis, prepared from Sphagnum peat. We analysed three profiles from three extensive ombrotrophic peatlands in northern Poland, in which the content of testate amoebae (TA) was examined and TA-inferred depth to the water table (DWT) was reconstructed. The new analysis of palynological samples regarding NPPs revealed that strong increases in HdV-10 content were mostly simultaneous to HdV-31A declines. However, the relations between both types were not statistically significant. The rapid increases in HdV-10, despite the fact that this type of conidiospores is related to drier habitats on peatlands, were tentatively interpreted as an indicator of rapid rises in the water table level which, in consequence, might have stimulated the production of these spores by fungi. In addition, a negative correlation between HdV-31A and Arcella discoides and positive one, but weaker, in case of HdV-10 (attributed by some authors to species Trichocladium opacum (Corda) S Hughes) and A. discoides show a link between mutual fluctuations of both NPPs and hydrological instabilities on peatland. The Bagno Kusowo bog, the westernmost peatland subjected to the study, displayed an intriguing agreement between the presence of peat sections with strong increases in HdV-10 and cold climate events affecting Europe. Our study reveals that counting even a limited number of NPP types during the standard pollen analysis of Sphagnum peat may support the interpretation of results, especially, in cases when the investigation lacks testate amoeba analysis. When the reconstruction of TA-inferred DWT is provided, it may introduce additional information about the patterns of hydrological dynamics.

scholarly journals Testate amoebae as a hydrological proxy for reconstructing water-table depth in the mires of south-eastern Australia

2019 ◽  
Vol 96 ◽  
pp. 701-710 ◽  
Author(s):  
Xianglin Zheng ◽  
Matthew J. Amesbury ◽  
Geoffrey Hope ◽  
Len F. Martin ◽  
Scott D. Mooney
Keyword(s):  
Water Table ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

Why Do Testate Amoeba Optima Related to Water Table Depth Vary?

2018 ◽  
Vol 77 (1) ◽  
pp. 37-55 ◽  
Author(s):  
Irina V. Kurina ◽  
Hongkai Li
Keyword(s):  
Water Table ◽  
Water Table Depth ◽  
Testate Amoeba

scholarly journals Effect of daily variation on the seasonality of testate amoebae community structure in different environments of a Neotropical floodplain

2015 ◽  
Author(s):  
Leilane T. Fatoreto Schwind ◽  
Rodrigo L. Arrieira ◽  
Juliana Déo Dias ◽  
Nadson Ressyé Simões ◽  
Claudia Costa Bonecker ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Time Lag ◽  
Species Abundance ◽  
Testate Amoebae ◽  
Mantel Test ◽  
Hydrodynamic Characteristics ◽  
Testate Amoeba ◽  
Ecological Communities

<p>Ecological communities are constantly restructuring in the short and long term in response to population dynamics and environmental variables. This study evaluated the structure of arcellinid and euglyphid testate amoebae planktonic communities in three environments of the Upper Paraná River basin, Brazil. We hypothesised that the community structure of testate amoebae is differentially influenced by environmental conditions, mainly in isolated lentic ecosystems, due the effect of the low-water period. In addition, we predicted that the response of testate amoeba communities to environmental changes is also affected by the distinct hydrodynamic characteristics of the environment. Plankton were sampled in the low- and high-water periods, and physical and chemical variables were calculated for each site. In order to evaluate the influence of environmental conditions on the variation in testate amoebae community structure over time, a time-lag analytical approach was used and significance was estimated using a Mantel test. A Kendall test coefficient was used to estimate the maintenance of species abundance on each day when sampling was carried out and for each water body. A redundancy analysis was also performed to assess the responses of testate amoeba communities to environmental change in the three studied environments. Bray–Curtis dissimilarity indices were calculated for the testate amoeba communities and the significance of the differences between communities was estimated using a Mantel test. Seventy-five taxa belonging to six families were identified. Environmental conditions influenced the richness, abundance, and dominance pattern of the testate amoebae communities, and distinct hydrodynamic characteristics of the environments affected the establishment of community structure.</p>

Ecohydrological dynamics of a degrading subarctic peatland: Implications for Arsenic mobility

2020 ◽  
Author(s):  
Jennifer Galloway ◽  
Mariusz Gałka ◽  
Graeme Swindles ◽  
Matt Amesbury ◽  
Stephen Wolfe ◽  
...  
Keyword(s):  
Water Table ◽  
Thick Layer ◽  
Plant Macrofossils ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
Permafrost Degradation ◽  
Downward Mobility ◽  
Regional Environment ◽  
Arsenic Mobility ◽  
Trophic Shift

&lt;p&gt;A peatland from subarctic Canada (Handle Lake 62&amp;#176;29&amp;#8217;26.44&amp;#8221;N, 114&amp;#176;23&amp;#8217;18.23&amp;#8221;W) is a degrading permafrost peatland chosen for detailed study due to a legacy of regional arsenic (As) contamination as a result of almost 8 decades of gold mining. The fate of permafrost peatlands and their element stores is unknown due to complex feedbacks between peat accumulation, hydrology, and vegetation that affect redox state and element mobility. We combine palynology with study of plant macrofossils, testate amoebae, organic matter composition, and bulk geochemistry preserved in a ca. 4180-4972 cal year old peat monolith retrieved from the Handle Lake peatland to reconstruct the ecohydrological dynamics to assess future trajectories of permafrost peat, and contaminant storage or release, in response to current and future warming. Sphagnum riparium macrofossils are rare in modern peat habitats and sub-fossils are rare in paleoecological records. Plant macrofossils of this taxon occur in an 11-cm thick layer together with Sphagnum angustifolium between 43 cm (ca.&amp;#160; 3390-3239 cal BP) and 25 cm depth (ca. 2755-2378 cal BP) in the monolith. The S. riparium sub-fossils are present with the hydrophilous testate amoebae species Archerella flavum, Hyalosphenia papilio and Difflugia globulosa that are used to quantitatively reconstruct a water table depth of 0-4 cm below the peat surface. Sub-fossils of S. riparium disappear at ca. 2755-2378 cal BP, likely due to an autogenic trophic shift and succession towards more acidophilic conditions favourable to species such as Sphagnum fuscum and Sphagnum russowii. We interpret the occurrence of S. riparium as an indicator of wet and minerotrophic conditions linked to peatland development form rich fen to oligotrophic bog.&amp;#160; Because S. riparium is a key pioneer species of disturbed peatlands that have experienced permafrost degradation it will likely be favoured in northern regions experiencing rapid climate warming. In the palynological record the proportion of Sphagnum-type A spores increases (up to 80%) between ca.&amp;#160; 3390-3239 cal BP and ca. 2755-2378 cal BP concurrent with a decline in other Sphagnum-type spores. A peak in micro- and macroscopic charcoal occurs between ca. 3557-3286 cal BP and ca. 3275-2771 cal BP, concurrent with a decline in Picea pollen and an increase in Alnus pollen. Regionally, between ca. 3500 and ca. 2500 cal BP Neoglacial climate prevailed with post-Neoglacial warming at ca. 2500 cal BP. It is therefore possible that regional fire occurrence stimulated permafrost degradation at ca. 3500 cal BP. Background As in the active layer monotlith is ~20-30 ppm. The upper 10 cm of the peat are impacted by aerial deposition of As from ore processing and concentrations range up to ~360 ppm. An increase in the concentration of As in the monolith from ~15-20 ppm at the base of the monolith to ~30-40 ppm during this interval may reflect water table depth dynamics that affected the mobility and fate of this redox sensitive element and/or downward mobility from layers impacted by contamination from mineral processing. Degradation of this permafrost within the Handle Lake peatland will release the currently stored As and other contaminants to the regional environment.&lt;/p&gt;

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