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TitleBehind the organic veil: assessing the impact of chemical deflocculation on organic content reduction and lacustrine Arcellinidat (testate amoebae) analysis
AuthorNasser, N A; Gregory, B R B; Steele, R E; Patterson, R T; Galloway, J MORCID logo
SourceMicrobial Ecology 2019 p. 1-16,
Alt SeriesNatural Resources Canada, Contribution Series 20190265
PublisherSpringer Science and Business Media LLC
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
ProvinceNorthwest Territories
NTS85I/05; 85I/12; 85J/07; 85J/08; 85J/09; 85J/10
Lat/Long WENS-114.8833 -113.8667 62.7000 62.2500
Subjectsenvironmental geology; Nature and Environment; Science and Technology; environmental studies; environmental impacts; surface waters; lakes; microorganisms; organic materials; sample preparation; statistical methods; faunal assemblages; Amoebae; Arcellinida; Giant Mine; Con Mine; Methodology; lacustrine sediments
Illustrationstables; location maps; flow diagrams; photomicrographs; diagrams; histograms
ProgramEnvironmental Geoscience Mackenzie River
ProgramPolar Continental Shelf Program
Released2019 08 20
AbstractArcellinida (testate lobose amoebae) are widely used as bio-indicators of lacustrine environmental change. Too much obscuring organic material in a gridded wet Petri dish preparation makes it difficult to observe all specimens present and slows quantification as the organic material has to be carefully worked through with a dissection probe. Chemical deflocculation using soda ash (Na2CO3·H2O), potassium hydroxide (KOH), or sodium hexametaphosphate ((NaPO3)6) has previously been shown to disaggregate and reduce organic content in lake sediments, but to date, no attempt has been made to comparatively evaluate the efficiency of these deflocculants in disaggregating organic content and their impact on Arcellinida analysis in lacustrine sediments. Here, we assess the effectiveness of soda ash, potassium hydroxide, and sodium hexametaphosphate treatments on removing organic content and the impact of those digestions on Arcellinida preservation in 126 sample aliquots subdivided from three sediment samples (YK-20, YK-25, and YK-57) collected from three lakes near Yellowknife, Northwest Territories, Canada. Following treatment, cluster analysis and Bray-Curtis dissimilarity matrix (BCDM) were utilized to determine whether treatments resulted in dissolution-driven changes in Arcellinida assemblage composition. Observed Arcellinida tests in aliquots increased drastically after treatment of organic-rich samples (47.5 - 452.7% in organic-rich aliquots and by 14.8%in aliquots with less organic matter). The BCDM results revealed that treatment with 5% KOH resulted in the highest reduction in observed organic content without significantly affecting Arcellinida assemblage structure, while soda ash and sodium hexametaphosphate treatments resulted in marginal organic matter reduction and caused severe damage to the arcellinidan tests.
Summary(Plain Language Summary, not published)
Arcellinida are small protists that secrete a test and are widely used as bio-indicators of lacustrine environmental change. Organic matter present in lake sediments often obscures the tests and is thus reduced using different chemical treatments prior to microscopic analysis. This study tests the efficacy of different chemical treatments and their impact on the preservation of Arcellinida in sediment samples collected from lakes in the Northwest Territories, Canada. The study shows that treatment with 5% potassium hydroxide (KOH) results in the highest reduction of organic matter content without significantly affecting Arcellinida assemblages. Soda ash and sodium hexametaphosphate resulted in marginal reduction of organic matter but caused damage to Arcellinida tests.

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