Patterson Lab Publications 2014-2016

2016

听

Contribution 153

Sulphur, K.C., Goldsmith, S.A., Galloway, J.M., Macumber, A.L., Griffith, F., Swindles, G.T., Patterson, R.T., Falck, H., Clark, I.D. 2016. Holocene fire regimes and treeline migration rates in sub-arctic Canada. Global and Planetary Change 145: 42-56. doi: 10.1016/j.gloplacha.2016.08.003.

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Sulphur, K.C., Goldsmith, S.A., Galloway, J.M., Macumber, A.L., Griffith, F., Swindles, G.T., Patterson, R.T., Falck, H., Clark, I.D. 2016. Holocene fire regimes and treeline migration rates in sub-arctic Canada. Global and Planetary Change 145: 42-56. doi: 10.1016/j.gloplacha.2016.08.003.

Holocene climate change resulted in major vegetation reorganization in sub-arctic Canada near modern treeline. However, little is known of the effects of long-term climate change on boreal forest composition and fire regimes below treeline in this region. We present a high-resolution vegetation and fire history from two sites within the modern boreal forest in the central Northwest Territories, Canada, to provide new insight on sub-arctic vegetation response to Holocene climate dynamics and the role of fire in boreal ecosystems. Palynological analysis of sediments retrieved from Waite and Danny’s lakes (informal) is used to reconstruct regional vegetation dynamics and boreal fire regimes. The longer Danny’s Lake record documents treeline expansion beginning at ca. 7430鈥�7220 cal yr BP. Integration of our new data with previous work shows that treeline expanded between ca. 4050 cal. yr BP and ca. 3840 cal yr BP at a rate of ca. 50 m/yr in response to the 1鈥�2 掳C increase in temperature estimated for the Holocene Thermal Maximum. Forest fires were relatively frequent during the early Holocene, before declining in frequency in response to development of cooler and wetter climate conditions associated with the Neoglacial (beginning after ca. 2200鈥�2320 cal yr BP). We document a trend of increasing fire frequency in the 20th century that is correlated with warming at this time. These dynamics south of modern treeline provide insight into factors creating heterogeneity in plant community responses to large-scale climate events in high northern latitudes and suggest that large scale reorganization of boreal vegetation and fire regimes can be expected over the coming decades.

听

Contribution 152

Nasser, N.A., Patterson, R.T., Roe, H.M., Galloway, J.M., Falck, H., Palmer, M.J., Spence, C., Sanei, H., Macumber, A.L., Neville, L.A. 2016. Lacustrine arcellinina (testate amoebae) as bioindicators of arsenic contamination. Microbial Ecology. 72 (1): 130-149. DOI:10.1007/s00248-016-0752-6

Winner 2018 Herbert Spencer Jennings Best Student Research Publication

Awarded by the International Society of Testate Amoeba Research at the International Symposium on Testate Amoeba 9 meeting, Belfast, Northern Ireland, September 12th, 2018.

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Read the Abstract - Contribution 152

Nasser, N.A., Patterson, R.T., Roe, H.M., Galloway, J.M., Falck, H., Palmer, M.J., Spence, C., Sanei, H., Macumber, A.L., Neville, L.A. 2016. Lacustrine arcellinina (testate amoebae) as bioindicators of arsenic contamination. Microbial Ecology. 72 (1): 130-149. DOI:10.1007/s00248-016-0752-6

Arcellininids (testate amoebae) were examined from 61 surface sediment samples collected from 59 lakes in the vicinity of former gold mines, notably Giant Mine, near Yellowknife, Northwest Territories, Canada to determine their utility as bioindicators of arsenic (As), which occurs both as a byproduct of gold extraction at mines in the area and ore-bearing outcrops. Cluster analysis (Q-R-mode) and detrended correspondence analysis (DCA) reveal five arcellininid assemblages, three of which are related to varying As concentrations in the sediment samples. Redundancy analysis (RDA) showed that 14 statistically significant environmental parameters explained 57听% of the variation in faunal distribution, while partial RDA indicated that As had the greatest influence on assemblage variance (10.7听%; p鈥�<鈥�0.10). Stress-indicating species (primarily centropyxids) characterized the faunas of samples with high As concentrations (median鈥�=鈥�121.7听ppm, max鈥�>鈥�10000听ppm, min鈥�=鈥�16.1听ppm, n鈥�=鈥�32), while difflugiid dominated assemblages were prevalent in substrates with relatively low As concentrations (median鈥�=鈥�30.2听ppm, max鈥�=鈥�905.2听ppm, min鈥�=鈥�6.3听ppm, n鈥�=鈥�20). Most of the lakes with very high As levels are located downwind (N and W) of the former Giant Mine roaster stack where refractory ore was roasted and substantial quantities of As were released (as As₂O₃) to the atmosphere in the first decade of mining. This spatial pattern suggests that a significant proportion of the observed As, in at least these lakes, are industrially derived. The results of this study highlight the sensitivity of Arcellinina to As and confirm that the group has considerable potential for assessing the impact of As contamination on lakes.

2015

Contribution 151

Patterson, R.T., Huckerby, G., Kelly, T.J., Swindles, G.T., Nasser, N.A. 2015. Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru. European Journal of Protistology. 51: 460-469.听https://doi.org/10.1016/j.ejop.2015.06.009

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Read the Abstract - Contribution 151

Patterson, R.T., Huckerby, G., Kelly, T.J., Swindles, G.T., Nasser, N.A. 2015. Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru. European Journal of Protistology. 51: 460-469.听https://doi.org/10.1016/j.ejop.2015.06.009

Organic rich sediments were obtained from seven core tops taken in Lake Quistococha, near the city of Iquitos in the Peruvian Amazon. Subsamples from 0 to 4听cm depth in each core were analyzed under dissecting light microscopy to carry out the first investigation of Arcellinida (testate lobose amoebae) from a lacustrine environment in this ecologically important region. The fauna was characterized by a low diversity, low abundance community dominated by centropyxids. This fauna is similar to 鈥榮tressed鈥� assemblages reported from temperate latitudes, except that test concentrations were two orders of magnitude lower than typical in temperate lakes. Principle arcellinidan stressors in Lake Quistococha likely include the low pH 4 conditions in the lake, and a general lack of suitable minerogenic material to construct tests in the organic rich lake substrate. The low pH conditions are the result of runoff and seepage of water high in dissolved organic carbon from the adjacent similarly low pH 4 terrestrial peatland. The dearth of minerogenic material is the result of the lake being isolated from riverine input for the past 鈭�2000 years, even during flooding events. Other limiting factors contributing to depressed arcellinidan populations may include nutrient supply, predation pressure, competition, and post-mortem taphonomic factors.

Contribution 150

Patterson, R.T., Swindles, G.T. 2015. Erratum to: Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (11,12):2963. doi: 10.1007/s00382-014-2415-y

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Patterson, R.T., Swindles, G.T. 2015. Erratum to: Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (11,12):2963. doi: 10.1007/s00382-014-2415-y

In the original publication, the first author鈥檚 first and last names were reversed. The correct name should be R. Timothy Patterson. The original article has been updated accordingly.

Contribution 149

Patterson, R.T., Swindles, G.T. 2015. Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (9,10):2293-2308. doi: 10.1007/s00382-014-2415-y

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Patterson, R.T., Swindles, G.T. 2015. Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (9,10):2293-2308. doi: 10.1007/s00382-014-2415-y

Our results reveal long-term trends in ice out dates (1836 鈥� 2013) for twelve lakes in Maine, New Brunswick and New Hampshire, in eastern North America. The trends are remarkably coherent between lakes (rs = 0.462鈥�0.933, p < 0.01) and correlate closely with the March鈥揂pril(MA) instrumental temperature records from the region(rs = 0.488鈥�0.816, p < 0.01). This correlation permits use of ice out dates as a proxy to extend the shorter MA instrumental record (1876鈥�2013). Mean ice out dates trended progressively earlier during the recovery from the Little Ice Age through to the 1940s, and gradually became later again through to the late 1970s, when ice out dates had returned to values more typical of the late nineteenth century. Post-1970鈥檚 ice out dates resumed trending toward earlier dates, with the twenty-first century being characterized by the earliest ice out dates on record. Spectral and wavelet time series analysis indicate that ice out is influenced by several teleconnections including the Quasi-biennial Oscillation, El Ni帽o-Southern Oscillation, North Atlantic Oscillation, as well as a significant correlation between inland lake records and the Atlantic Multidecadal Oscillation. The relative influence of these teleconnections is variable with notable shifts occurring after ~1870, ~1925, and ~1980鈥�2000. The intermittent expression of these cycles in the ice out and MA instrumental record is not only influenced by absolute changes in the intensity of the various teleconnections and other climate drivers, but through phase interference between teleconnections, which periodically damps the various signals.

听	Contribution 148 Nasser, N.A., Patterson, R.T. 2015. Conicocassis, a new genus of Arcellinida (Testate Lobose Amoebae). Palaeontologia Electronica. 18.3.46A: 1-11. (Read the PDF)

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Nasser, N.A., Patterson, R.T. 2015. Conicocassis, a new genus of Arcellinida (Testate Lobose Amoebae). Palaeontologia Electronica. 18.3.46A: 1-11.

Superfamily Arcellinina听(informally known as thecamoebians or testate lobose amoebae) are a group of shelled benthic protists common in most Quaternary lacustrine sediments. They are found worldwide, from the equator to the poles, living in a variety of fresh to brackish aquatic and terrestrial habitats. More than 130 arcellininid species and strains are ascribed to the genus Centropyxis Stein, 1857 within the family Centropyxidae Jung, 1942, which includes species that are distinguished by having a dorsoventral-oriented and flattened beret-like test (shell). Conicocassis, a new arcellininid genus of Centropyxidae differs from other genera of the family, specifically genus Centropyxis and its type species C. aculeata (Ehrenberg, 1932), by having a unique test comprised of two distinct components; a generally ovoid to subspherical, dorsoventral-oriented test body, with a pronounced asymmetrically positioned, funnel-like flange extending from a small circular aperture. The type species of the new genus, Conicocassis pontigulasiformis (Beyens et al., 1986) has previously been reported from peatlands in Germany, the Netherlands and Austria, as well as very wet mosses and aquatic environments in High Arctic regions of Europe and North America. The occurrence of the species in lacustrine environments in the central Northwest Territories extends the known geographic distribution of the genus in North America considerably southward.

Contribution 147

Crann, C.A., Patterson, R.T., Macumber, A.L., Galloway, J.M., Roe, H.M., Blaauw, M., Swindles, G.T., Falck, H. 2015. Sediment accumulation rates in subarctic lakes: insights into age-depth modeling from 22 dated lake records from the Northwest Territories, Canada. Quaternary Geochronology. 27: 131-144. https://doi.org/10.1016/j.quageo.2015.02.001

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Crann, C.A., Patterson, R.T., Macumber, A.L., Galloway, J.M., Roe, H.M., Blaauw, M., Swindles, G.T., Falck, H. 2015. Sediment accumulation rates in subarctic lakes: insights into age-depth modeling from 22 dated lake records from the Northwest Territories, Canada. Quaternary Geochronology. 27: 131-144. https://doi.org/10.1016/j.quageo.2015.02.001

Age-depth modeling using Bayesian statistics requires well-informed prior information about the behavior of sediment accumulation. Here we present average sediment accumulation rates (represented as deposition times, DT, in yr/cm) for lakes in an Arctic setting, and we examine the variability across space (intra- and inter-lake) and time (late Holocene). The dataset includes over 100 radiocarbon dates, primarily on bulk sediment, from 22 sediment cores obtained from 18 lakes spanning the boreal to tundra ecotone gradients in subarctic Canada. There are four to twenty-five radiocarbon dates per core, depending on the length and character of the sediment records. Deposition times were calculated at 100-year intervals from age-depth models constructed using the ‘classical’ age-depth modeling software Clam. Lakes in boreal settings have the most rapid accumulation (mean DT 20卤10 yr/cm), whereas lakes in tundra settings accumulate at moderate (mean DT 70卤10 yr/cm) to very slow rates, (>100yr/cm). Many of the age-depth models demonstrate fluctuations in accumulation that coincide with lake evolution and post-glacial climate change. Ten of our sediment cores yielded sediments as old as c. 9000cal BP (BP=years before AD 1950). From between c. 9000cal BP and c. 6000cal BP, sediment accumulation was relatively rapid (DT of 20-60yr/cm). Accumulation slowed between c. 5500 and c. 4000cal BP as vegetation expanded northward in response to warming. A short period of rapid accumulation occurred near 1200cal BP at three lakes. Our research will help inform priors in Bayesian age modeling.

Contribution 146

Galloway, J.M., Palmer, M.J., Jamieson, H.E., Patterson, R.T., Nasser, N.A., Falck, H., Macumber, A.L., Goldsmith, S.A., Sanei, H., Normandeau, P., Hadlari, T., Roe, H.M., Neville, L.A., Lemay, D. 2015. Geochemistry of lakes across ecozones in the Northwest Territories and implications for the distribution of arsenic in the Yellowknife region. Part 1: Sediments. GSC Open file 7908. https://doi.org/10.4095/296954

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Galloway, J.M., Palmer, M.J., Jamieson, H.E., Patterson, R.T., Nasser, N.A., Falck, H., Macumber, A.L., Goldsmith, S.A., Sanei, H., Normandeau, P., Hadlari, T., Roe, H.M., Neville, L.A., Lemay, D. 2015. Geochemistry of lakes across ecozones in the Northwest Territories and implications for the distribution of arsenic in the Yellowknife region. Part 1: Sediments. GSC Open file 7908. https://doi.org/10.4095/296954

We obtained near total element geochemistry on 211 near-surface sediment samples from lakes along a transect across the Western Interior Platform to the central portion of the Slave Geological Province with a focus near the City of Yellowknife, Northwest Territories, to document regional concentrations of arsenic (As) and other elements in lake sediments. Concentrations of major and trace elements, including elements of potential human and ecological concern (As, Cd, Cr, Cu, Pb, Zn), were extracted from sediments using a modified aqua regia digestion. Concentrations of As exceed Canadian federal guidelines for the protection of aquatic life in most of the lakes sampled in the Slave Geological Province. Seventy one percent (n=149) of all sediment samples contain As concentrations higher than the Canadian Council of Ministers of the Environment (CCME) Interim Freshwater Sediment Quality Guideline of 5.9 mg/kg and 54% (n=114) of the samples contain As concentrations that exceed the CCME Probable Effect Level of 17 mg/kg. Sediments with the highest As concentrations are from lakes near the City of Yellowknife and likely reflect a combination of contamination associated with past industrial activity and geogenic input from mineralized bedrock and derived surficial materials (median As concentration 107.9 mg/kg, range 6.30->10,000+, n=95). Arsenic concentrations in lake sediments sampled elsewhere in the central Northwest Territories are lower (Ingraham Trail, median As concentration 10.6 mg/kg, range 1.9-101.6, n=27; Tibbitt to Contwoyto Winter Road, median As concentration 7.9 mg/kg, 0.3-101.4, n=52; Western Interior Platform, median As concentration 1.1 mg/kg, 0.1-7.1, n=37). Based on our data and a review of existing literature, background As concentration in lake sediments appear to ~25 mg/kg for the Yellowknife region, and lower for other regions in the central NWT. Other elements (Cr, Cu, Pb, Zn) are below sediment quality guidelines in the majority of lake sediments sampled.

Contribution 145

Palmer, M.J., Galloway, J., Jamieson, H.E., Patterson, R.T., Falck, H., andKokelj, S.V. 2015. The concentration of arsenic in lake waters of the Yellowknife area. NWT Open File 2015-06, NWT Geoscience Office,
Yellowknife 25 p. DOI: 10.13140/RG.2.1.2582.5041.

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Palmer, M.J., Galloway, J., Jamieson, H.E., Patterson, R.T., Falck, H., andKokelj, S.V. 2015. The concentration of arsenic in lake waters of the Yellowknife area. NWT Open File 2015-06, NWT Geoscience Office,
Yellowknife 25 p. DOI: 10.13140/RG.2.1.2582.5041.

Ninety-eight lakes were sampled within a 30 km radius of the City of Yellowknife to document elemental concentrations in surface waters in an area exposed to 50 years of emissions from gold ore processing.听 Concentrations of As, Sb, SO₄ are elevated in lakes within 17.5 km of the Giant Mine relative to lakes beyond this distance.听 Arsenic concentrations were highest in small lakes (<100 ha) that were downwind and proximal to the historic stacks, suggesting a gradient in impact from historic roaster operations at the Giant Mine consistent with the predominant wind direction in the region.听 Concentrations of As exceeded the federal drinking water guidelines of 10 ug/L for many of the lakes sampled within 12 km of the roaster stacks, and in some lakes were more than 60 times this limit.听 This study provides an extensive survey of elemental concentrations in regional lakes surrounding the City of Yellowknife and should be supported by future work to investigate drivers of variation in As concentrations in surface waters, interannual variability in water chemistry, and the long-term fate of As and other elements of potential concern in these lakes.

2014

Contribution 144

Patterson, R.T.听2014. In Memoriam. Dr. Franco Medioli April 1, 1935 – January 31, 2014. Palaeontologia Electronica. 17.2.4E. 4 p. https://doi.org/10.26879/144

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Patterson, R.T. 2014. In Memoriam. Dr. Franco Medioli April 1, 1935 – January 31, 2014. Palaeontologia Electronica. 17.2.4E. 4 p.https://doi.org/10.26879/144

Professor Franco Medioli passed away peacefully on January 31, 2014, in Halifax, Nova Scotia, at the age of 78. The Cushman Foundation had only three months earlier honored him with the Joseph A. Cushman Award for Excellence in Foraminiferal Research at the annual meeting of the Geological Society of America in Denver, Colorado. Due to poor health, he was unable to accept the award in person. This lifetime achievement award recognized his research on the paleoecological significance of marginal-marine foraminifera as a critical tool in reconstructing Holocene sea-level, as well as his contributions to resolving taxonomic issues within the freshwater thecamoebians (testate amoebae).

听	Contribution 143 Patterson, R.T. 2014.听Mediolus, a new genus of Arcellacea (Testate Lobose Amoebae). Palaeontologia Electronica. 17.2.28A. 8 p. (Read the PDF)

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Patterson, R.T. 2014.听Mediolus, a new genus of Arcellacea (Testate L oboseAmoebae). Palaeontologia Electronica. 17.2.28A. 8 p.

Mediolus, a new arcellacean genus of the Difflugidae (informally known as thecamoebia, testate rhizopods, or testate lobose amoebae) differs from other genera of
the family in having distinctive tooth-like inward oriented apertural crenulations and
tests generally characterized by a variable number of hollow basal spines.

听	Contribution 142 Roe, H.M.,听Patterson, R.T.听2014. Arcellacea (testate amoebae) as bio-indicators of road salt听contamination in lakes. Microbial Ecology. 68 (2):299-313. DOI: 10.1007/s00248-014-0408-3 Read the PDF)

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Roe, H.M.,听Patterson, R.T.听2014. Arcellacea (testate amoebae) as bio-indicators of road salt听contamination in lakes. Microbial Ecology. 68 (2):299-313. DOI: 10.1007/s00248-014-0408-3

Winter deicing operations occur extensively in mid- to high-latitude metropolitan regions around the world and result in a significant reduction in road accidents. Deicing salts can, however, pose a major threat to water quality and aquatic organisms. In this paper we examine the utility of Arcellacea (testate amoebae) for monitoring lakes that have become contaminated by winter deicing salts, particularly sodium chloride. We analysed 50 sediment samples and salt-related water property variables (chloride concentrations; conductivity) from 15 lakes in the Greater Toronto Area and adjacent areas of southern Ontario, Canada. The sampled lakes included lakes in proximity to major highways and suburban roads, and control lakes in forested settings away from road influences. Samples from the most contaminated lakes, with chloride concentrations in excess of 400 mg/l and conductivities of >800 碌S/cm, were dominated by species typically found in brackish and/or inhospitable lake environments and by lower faunal diversities (lowest Shannon Diversity Index values) than samples with lower readings. Q-R-mode cluster analysis and Detrended Correspondence Analysis (DCA) resulted in the recognition of four assemblage groupings. These reflect varying levels of salt contamination in the study lakes, along with other local influences, including nutrient loading. The response to nutrients can, however, be isolated if the planktic eutrophic indicator species听Cucurbitella tricuspis听is removed from the counts. The findings show that the group has considerable potential for biomonitoring in salt-contaminated lakes, and their presence in lake sediment cores may provide significant insights into long-term benthic community health, which is integral for remedial efforts.

Contribution 141

Neville, L.A.,听Patterson, R.T.,听Gammon, P., Macumber, A.L. 2014. Relationship between ecological indicators (Arcellacea), total mercury concentrations and grain size in lakes within the Athabaska Oil Sands region, Alberta. Environmental Earth Sciences 72:577-588. DOI: 10.1007/s12665-013-2979-6.

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Read the Abstract - Contribution 141

Neville, L.A.,听Patterson, R.T.,听Gammon, P., Macumber, A.L. 2014. Relationship between ecological indicators (Arcellacea), total mercury concentrations and grain size in lakes within the Athabaska Oil Sands region, Alberta. Environmental Earth Sciences 72:577-588. DOI: 10.1007/s12665-013-2979-6.

Industrial mercury (Hg) sources associated with the processing of Athabasca oil sands (AOS), Alberta,Canada, may pose an environmental risk to nearby water bodies via either waterborne or airborne transport. Using a dataset derived from 63 lakes in the area, this study investigates the relationships between total-Hg (THg), organic matter, grain size, and lake ecology as measured by environmentally sensitive arcellacean (testate lobose amoebae) communities. The lakes studied include 59 lakes within a 75 km radius of the operations, plus four distal lakes ~150 km from the main industrial operations. Hg transport to the lakes is primarily through airborne pathways. The four distal lakes in the Peace鈥揂thabasca Delta (~150 km downstream of the AOS operations) were examined to determine if the operation is emitting potential waterborne inputs, in addition to airborne inputs, and to identify any associated impact to those ecosystems. Total mercury in lakes close to the AOS were similar to values recorded in lakes farthest away. THg was most closely linked to the silt fraction, suggesting much of the Hg in these lakes is minerogenic in origin, either adsorbed and/or lattice bound. THg is not statistically related to organic matter as has been observed in other Canadian lakes. The ecologic response to THg levels was investigated via the distribution of key indicator species and, or species diversity (Shannon diversity index). The spatial extent of arcellacean ecosystem stress in the study lakes did not correlate with THg concentrations. This is perhaps due to the generally low THg levels found in these lakes, all except one had THg concentrations lower than current CCME guidelines. While these findings may rule out direct link between THg concentrations in the lakes and observed Arcellacea faunas, ecosystem stress unrelated to THg was observed northeast of the AOS, which warrants further examination. The results of this research suggest that the natural lake arcellacean faunas in the region are not being significantly impacted by current THg concentrations.

Contribution 140

Macumber, A.L.,,听Patterson, R.T.,听Roe, H.M., Neville, L.A. Swindles, G.T. 2014. Autoecological approaches to resolve subjective taxonomic divisions within Arcellacea. Protist. 165: 305-316. DOI:10.1016/j.protis.2014.03.004

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Macumber, A.L.,听Patterson, R.T.,听Roe, H.M., Neville, L.A. Swindles, G.T. 2014. Autoecological approaches to resolve subjective taxonomic divisions within Arcellacea. Protist. 165: 305-316. DOI:10.1016/j.protis.2014.03.004

Arcellacea (testate lobose amoebae) are important lacustrine environmental indicators that have been used in paleoclimatic reconstructions, assessing the effectiveness of mine tailings pond reclamation projects and for studying the effects of land use change in rural, industrial and urban settings. Recognition of ecophenotypically significant infraspecific鈥榮trains鈥� within arcellacean assemblages has the potential to enhance the utility of the group in characterizing contemporary and paleoenvironments. We present a novel approach which employs statistical tools to investigate the environmental and taxonomic significance of proposed strains. We test this approach on two identified strains:听Difflugia protaeiformis听Lamarck strain 鈥榓cuminata鈥� (DPA), characterized by fine grained agglutination, and听Difflugia protaeiformis听Lamarck strain 鈥榗laviformis鈥� (DPC), characterized by coarse grained agglutination. Redundancy analysis indicated that both organisms are associated with similar environmental variables. No relationship was observed between substrate particle size and abundance of DPC, indicating that DPC has a size preference for xenosomes during test construction. Thus DPC should not be designated as a distinct strain, but rather form a species complex with DPA. This study elucidates the need to justify the designation of strains based on their autecology in addition to morphological stability.

Contribution 139

Upiter, LM., Vermaire, J.C., Patterson, R.T.,听Crann, C., Galloway, J.M., Macumber, A.L., Neville, L.A., Swindles, G.T.,听 Falck, H., Roe, H.M., Pisaric, M.F.J. 2014. 听Middle to late Holocene chironomid-inferred July temperatures for the central Northwest Territories, Canada. Journal of听 Paleolimnology.听52:11-26. DOI 10.1007/s10933-014-9775-5

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Read the Abstract - Contribution 139

Upiter, LM., Vermaire, J.C., Patterson, R.T.,听Crann, C., Galloway, J.M., Macumber, A.L., Neville, L.A., Swindles, G.T.,听 Falck, H., Roe, H.M., Pisaric, M.F.J. 2014. 听Middle to late Holocene chironomid-inferred July temperatures for the central Northwest Territories, Canada. Journal of听 Paleolimnology.听52:11-26. DOI 10.1007/s10933-014-9775-5

We analyzed subfossil chironomids, sediment organic matter and sediment particle size data from a 1.11-m long freeze core collected from 杏吧原创 Lake (unofficial name), located approximately 120 km north of the modern treeline. This well-dated core spans the last ca. 6,500 years. Two chironomid transfer functions were applied to infer mean July air temperatures. Our results indicated that the chironomid-inferred temperatures from this lake sediment record did not pass a significance test, suggesting that other factors in addition to temperature may have been important in structuring the chironomid community through time. Although not statistically significant, the chironomid-inferred temperatures from this site do follow a familiar pattern, with highest inferred temperatures occurring during the Holocene Thermal Maximum (~6鈥�4 cal kyr BP), followed by a long-term cooling trend, which is reversed during the last 600 years. The largest change in the chironomid assemblage, which occurred between ca. 4,600 and 3,900 cal yr BP is possibly related to the well-documented northward advance and subsequent retreat of treeline in this region.

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2016

Contribution 153

Sulphur, K.C., Goldsmith, S.A., Galloway, J.M., Macumber, A.L., Griffith, F., Swindles, G.T., Patterson, R.T., Falck, H., Clark, I.D. 2016. Holocene fire regimes and treeline migration rates in sub-arctic Canada. Global and Planetary Change 145: 42-56. doi: 10.1016/j.gloplacha.2016.08.003.

Contribution 152

Nasser, N.A., Patterson, R.T., Roe, H.M., Galloway, J.M., Falck, H., Palmer, M.J., Spence, C., Sanei, H., Macumber, A.L., Neville, L.A. 2016. Lacustrine arcellinina (testate amoebae) as bioindicators of arsenic contamination. Microbial Ecology. 72 (1): 130-149. DOI:10.1007/s00248-016-0752-6

Winner 2018 Herbert Spencer Jennings Best Student Research Publication

2015

Contribution 151

Patterson, R.T., Huckerby, G., Kelly, T.J., Swindles, G.T., Nasser, N.A. 2015. Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru. European Journal of Protistology. 51: 460-469.听https://doi.org/10.1016/j.ejop.2015.06.009

Contribution 150

Patterson, R.T., Swindles, G.T. 2015. Erratum to: Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (11,12):2963. doi: 10.1007/s00382-014-2415-y

Contribution 149

Patterson, R.T., Swindles, G.T. 2015. Influence of ocean鈥揳tmospheric oscillations on lake ice phenology in eastern North America. Climate Dynamics. 45 (9,10):2293-2308. doi: 10.1007/s00382-014-2415-y

Contribution 148

Nasser, N.A., Patterson, R.T. 2015. Conicocassis, a new genus of Arcellinida (Testate Lobose Amoebae). Palaeontologia Electronica. 18.3.46A: 1-11.

Contribution 147

Contribution 146

Contribution 145

Palmer, M.J., Galloway, J., Jamieson, H.E., Patterson, R.T., Falck, H., andKokelj, S.V. 2015. The concentration of arsenic in lake waters of the Yellowknife area. NWT Open File 2015-06, NWT Geoscience Office, Yellowknife 25 p. DOI: 10.13140/RG.2.1.2582.5041.

2014

Contribution 144

Patterson, R.T.听2014. In Memoriam. Dr. Franco Medioli April 1, 1935 – January 31, 2014. Palaeontologia Electronica. 17.2.4E. 4 p. https://doi.org/10.26879/144

Contribution 143

Patterson, R.T. 2014.听Mediolus, a new genus of Arcellacea (Testate Lobose Amoebae). Palaeontologia Electronica. 17.2.28A. 8 p.

Contribution 142

Roe, H.M.,听Patterson, R.T.听2014. Arcellacea (testate amoebae) as bio-indicators of road salt听contamination in lakes. Microbial Ecology. 68 (2):299-313. DOI: 10.1007/s00248-014-0408-3

Contribution 141

Neville, L.A.,听Patterson, R.T.,听Gammon, P., Macumber, A.L. 2014. Relationship between ecological indicators (Arcellacea), total mercury concentrations and grain size in lakes within the Athabaska Oil Sands region, Alberta. Environmental Earth Sciences 72:577-588. DOI: 10.1007/s12665-013-2979-6.

Contribution 140

Macumber, A.L.,,听Patterson, R.T.,听Roe, H.M., Neville, L.A. Swindles, G.T. 2014. Autoecological approaches to resolve subjective taxonomic divisions within Arcellacea. Protist. 165: 305-316. DOI:10.1016/j.protis.2014.03.004

Contribution 139

Palmer, M.J., Galloway, J., Jamieson, H.E., Patterson, R.T., Falck, H., andKokelj, S.V. 2015. The concentration of arsenic in lake waters of the Yellowknife area. NWT Open File 2015-06, NWT Geoscience Office,
Yellowknife 25 p. DOI: 10.13140/RG.2.1.2582.5041.