Thecamoebian communities as proxies of seasonality in Lake Sadatal in the Ganga Yamuna Plains of North India

Abstract

Thecamoebians are testate protists that occur in a variety of freshwater habitats and brackish environments. They have been successfully used as proxies for a variety of environmental and climatic parameters in limnological and paleolimnological studies. The perennial Lake Sadatal is situated near the small town of Mallanwan (Latitude 27°3 ' 0" North and Longitude 80° 9' 0" East) in the Ganga-Yamuna Plains of North India. Lake Sadatal is a shallow remnant of a past oxbow lake left by the meandering Ganga River and its tributaries (maximum depth ~1.5 m during summer and ~3.0 m during July-August monsoon season). The soil around this region is saline, sodium rich, and the maximum soil alkalinity is pH 10. This region shows strong seasonality, and average atmospheric temperatures during winter (December-March) range between 7-20C and during summer (April-June) range between 21-45C (2005-2007). Taxonomically diverse and mixed thecamoebians were recovered from Lake Sadatal showing distinct summer and winter communities for three years. Centropyxids and Arcellenids dominate the low humidity, low precipitation cooler months (October-March) whereas Amphitrema spp. and Difflugia oblonga "triangularis" dominate summer and the high precipitation, high humidity monsoon months (April-September). Dominance of Amphitrema spp. is related to abundance of aquatic weed Lemna detritus at the lake bottom during summer. Total concentrations of thecamoebians were higher during summer monsoon months than winter.

An Assessment of Sub-Meter Scale Spatial Variability of Arcellinida (Testate Lobose Amoebae) Assemblages in a Temperate Lake: Implications for Limnological Studies

“…Arcellinida (also known as testate lobose amoebae) are a group of unicellular benthic protozoans that is abundantly preserved in lake sediments from the equator to poles (e.g. [1][2][3][4][5][6][7][8][9][10][11][12]).…”

“…Arcellinida are mainly found in freshwater habitats (e.g. lakes, rivers and ponds; [1][2][3][4][5][6][7][8][9][10][11][12][13]) and, to a lesser extent, in brackish water settings, including tidal marshes [17,18]. The beret-or sac-like shaped tests (shells) of Arcellinida are either autogenous (secreted by the organism) or xenogenous (comprised of agglutinated grains obtained from the substrate), and range from ca.…”

“…Additionally, only a small number of Arcellinida-based intra-lake surveys currently exist, none of which were conducted at a sub-meter scale (e.g. [2,3,7]).…”

First record of siliceous shell plates of Scutiglypha sp. (Amoebozoa: Thecamoeba: Euglyphidae) from Lake Enspel (upper Oligocene, Westerwald Mountains, Germany)

“…Thecamoebians are important as environmental indicators (e.g. Farooqui et al 2012) and are increasingly used in palaeoenvironmental reconstructions (e.g. Escobar 2005).…”

Assessment of FlowCam VisualSpreadsheet as a potential tool for rapid semi-automatic analysis of lacustrine Arcellinida (testate lobose amoebae)

“…During the past few decades, Arcellinida have become valuable bioindicators of ecosystem health, water quality, and seasonal and land-use change (e.g., urbanization, agriculture, forestry, and mining; e.g., Asioli et al, 1996;Dalby et al, 2000;Farooqui et al, 2011;Nasser et al, 2016;Neville et al, 2010;Patterson et al, 1996;Patterson et al, 2013;Patterson and Kumar, 2000ab;Reinhardt et al, 1998;Roe and Patterson, 2006;Roe et al, 2010;Medioli and Scott, 1983). The growing interest in Arcellinida has mainly been linked to their high abundance in organic-rich lake sediments, their rapid reproduction time (days to weeks), the durability of their tests, and their sensitivity to environmental change (Patterson and Kumar, 2002).…”