杏吧原创

Birk, et al. 2022. Perceptions of freshwater algal blooms, causes and health among New Brunswick lakefront property owners. Environmental Management. 71: 249-259. https://doi.org/10.1007/s00267-022-01736-2

Changes to water conditions due to eutrophication and climate change have resulted in the proliferation of harmful algal blooms in freshwater and marine environments globally, including in Canadian lakes. We developed and administered an online survey to evaluate the awareness of these blooms and the accompanying health risks in a sample of New Brunswick waterfront cottage and homeowners. The survey was distributed to lake and cottage associations in New Brunswick and was completed by 186 eligible respondents. Participants were asked to about information about the water quality of their lake, awareness about algae blooms, sociodemographic and cottage characteristics, and complete a self-rated measure of physical and mental health. While approximately 75% of participants reported that the quality of their lake water was good or very good, 40% indicated that algae blooms were a concern. We found no statistically signi cant differences in self-reported physical or mental health between those who were aware of algae blooms at their cottage and those who weren鈥檛 (p> 0.05). Participants expressed concern about the impacts of algal blooms on the health of their pets, and wildlife. While climate change was the most identi ed cause of algal blooms, there was substantial heterogeneity in the responses. Taken together, the ndings from our survey suggest that cottage owners in New Brunswick are aware and concerned about the impacts of algae blooms, however, there is a need to provide additional information to lake associations about the causes of these blooms.

Nguyen, et al. 2022. Project summary of samples collected in support of the Climate Controls on Long-term Hydrological Change in the Mackenzie River Basin project, Yukon and Northwest Territories, Environmental Geoscience Program and ArcticNet Project 51. Geological Survey of Canada, Open File 8919, 2022, 85 pages. https://doi.org/10.4095/330928

The Mackenzie River Basin is experiencing warming surface temperatures. Warmer temperatures may be affecting water levels and flows, causing warmer/drier winters, thinning ice, thawing permafrost, and changes to the surrounding ecosystems. A combined western science and Traditional Knowledge approach is being used in the study 鈥淟ong-term hydrological dynamics of the Mackenzie River Basin鈥� to create new knowledge on how and why water levels have changed in the Mackenzie River Basin. Our study focuses on the Gwich鈥檌n Settlement Area. By better understanding how past climate change has affected water levels in the basin, we will be able to make better predictions how current and future climate change may alter water levels.

This Open File reports on the western science aspect of the study of vertical sections of peat (鈥減eat cores鈥�) collected from peatbogs in and around the Gwich鈥檌n Settlement Area. The Traditional Knowledge component of the study is being led by Sharon Snowshoe (Gwich鈥檌n Tribal Council, Gwich鈥檌n Department of Cultural Heritage) and Trevor Lantz (University of Victoria) and is not included in this report.

Peatlands are ideal for the study of past climate change. Peat moss and other vegetation accumulates over time in them. Eight peat cores were collected from in and around the Gwich鈥檌n Settlement Area. Some of the peat cores were collected with a peat corer designed and made at the University of Alberta and some were collected with a saw to dig out a square block of peat. The peat cores range in depth from 93 cm to 22 cm. The peat cores were sliced at 5 mm or 1 cm intervals throughout their depth, and then sampled for various analyses, including 1) study of tiny fossils (micropaleontology; testate amoebae), pollen, remains of plants, and charcoal to reconstruct changes in vegetation, fire, and water levels over time; 2) geochemistry (stable isotopes) to reconstruct changes in moisture; 3) age dating to know how old the peat cores are; 4) metal concentrations; and, 5) HAWK pyrolysis to know more about the organic matter in the peat cores.

A catalogue of the cores, the samples, and the results of the age dating and organic matter analysis are included in this report. Of the peatlands sampled in the Gwich鈥檌n Settlement Area, one has a pH of <4 (ombrotrophic bog). The peat cores range in age from 214 years old to 4993 years old. The results of the organic matter analysis show that most of the peat bogs have become wetter in the more recent years.

Nagwichoonjik gwa鈥櫭爊 j霉k gweendoo gwiiyeendoo gwiniidhah. Gwiiyeendoo gwiniidhaa k鈥檌igh猫鈥� chuu ej霉k diinch鈥檜u, khaii guuzhik gwiiyeendo gwiniidhaa ts鈥櫭爐 guugaii, 艂uu didril, nan t鈥檈h gwithatan nagwaaghaii ts鈥櫭爐 nan ej霉k t鈥檌gwinjih. Jii gwitr鈥檌t geenjit gaoni艂tyin kat ts鈥櫭爐 yi鈥檈enoo Dinjii Zhuh nits鈥櫭瞣 gugwiindai鈥� gwinjik nihkhah Nagwichoonjik gwa鈥櫭爊 chuu dagwah艂eii yi鈥檈enoo gwiinli鈥� geenjit gik鈥檌gaanjii k鈥檌igh猫鈥� Nagwichoonjik gwinagoo鈥檈e gwa鈥櫭爊 chuu jaghadeh ej霉k diinch鈥檜u gik鈥檌tr鈥檃anjih. Gwich鈥檌n n脿nhkak dagoonch鈥檜u geenjit iisrits鈥櫭爐 gik鈥檌tr鈥檃anjih. Nagwichoonjik gwa鈥櫭爊 yi鈥檈enoo d脿i鈥� dagwiinch鈥檜鈥� geenjit gahgwidandaii k鈥檌igh猫鈥� j霉k ts鈥櫭爐 yeendoo chuu dagwiheech鈥檃a gik鈥檌traanjih.

Gwich鈥檌n N脿nhkak gwats鈥櫭爐 n矛n鈥� tr鈥檕onjik, geenjit gaoniltin kat geenjit jidii gik鈥檌gaanjik jii gwidinithit艂鈥檕o gwizh矛t goo鈥檃ih. Sharon Snowshoe (Gwich鈥檌n Tribal Council, Gwich鈥檌n Department of Cultural Heritage) ts鈥櫭爐 Trevor Lantz (University of Victoria) Dinjii Zhuh k鈥檡uu tr鈥檌gwindaii gwinjik gik鈥檌tr鈥檃anjii geenjit chit giinlii ts鈥櫭爐 guugwitr鈥檌t jii gwidinithit艂鈥檕o gwizh矛t goo鈥檃ih kw脿h.

Nan trah kak n矛n鈥� nahshii geenjit gik鈥檛r鈥檃anjii k鈥檌igh猫鈥� yi鈥檈enoo diinagoo鈥檈e nits鈥櫭瞣 ej霉k t鈥檌gwinjii gik鈥檌tr鈥檃anjih. Nan trah kak n矛n鈥� ts鈥櫭爐 gwinzhih nih艂inehch鈥檌鈥� gweedhaa guuzhik ezhik gwa鈥櫭爊 nahshih. N脿nhkak gwa鈥櫭爊 nan trah nihk鈥檌i daan nih艂inehch鈥檌鈥� goo鈥檃ii gwats鈥櫭爐 n矛n鈥� chyah tr鈥檕onjik. Nan zh矛t v脿h khatr鈥檌gyit University of Alberta danh tr鈥檌艂tsaii ts鈥檃t nan tr鈥檌t鈥檌i gwi鈥檌itsii h脿h chan n矛n鈥� tr鈥檕onjik. Jii n矛n鈥� 93 cm g貌o 22 cm diditih. N矛n鈥� 5 mm g貌o 1 cm diditii tr鈥檌int鈥檜鈥� t艂鈥檈e nih艂inehch鈥檌鈥� geenjit vizh矛t kagugwinah鈥櫭琻鈥�, jii geenjit kagugwinah鈥櫭琻鈥�, 1) gwinzhih nih艂inehch鈥檌鈥� ts鈥櫭爐 chii juuk鈥櫭爊鈥� k鈥櫭瑃 vizh矛t diinich鈥檜u geenjit gik鈥檌tr鈥檃anjii k鈥檌igh猫鈥� yeenoo nits鈥櫭瞣 gwinzhih nahshii, kw脿n鈥� gwiinli鈥� ts鈥櫭爐 chuu dagwiinch鈥櫭光�� geenjit gik鈥檌gaanjih; 2) vizh矛t ejiich鈥檌i tsal nih艂inehch鈥檌鈥� goonlii geenjit gik鈥檌tr鈥檃anjii k鈥檌igh猫鈥� yeenoo nan zh矛t chuu dagwiinch鈥檜鈥� natr鈥檌gwi艂tsaii; dahthee aii n矛n鈥� ezh矛k goo鈥檃ii geenjit gwizh矛t tr鈥檌gwinah鈥櫭琻鈥�; iitsii dagwah艂eii gwizh矛t t鈥檌inch鈥檜u geenjit tr鈥檌gwinah鈥櫭琻鈥� ts鈥櫭爐, thah k鈥檌igh猫鈥� nan dagoonch鈥檜u gwizh矛t gugwinah鈥櫭琻鈥� k鈥檌igh猫鈥� aii n矛n鈥� zh矛t nih艂inehch鈥檌鈥� jid矛i diinch鈥檜u gik鈥檌tr鈥檃anjih.

N矛n鈥� nih艂inehch鈥檌鈥� tr鈥檕onjik ts鈥櫭爐 dagwahthee ezhik t鈥檌inch鈥檜鈥� geenjit gik鈥檌tr鈥檃anjik jii gwizh矛t gwidinithit艂鈥檕h. Gwich鈥檌n N脿nhkak gwa鈥櫭爊 gwats鈥櫭爐 n矛n鈥� tr鈥檕onjik ts鈥櫭爐 vizh矛t tr鈥檌gwinah鈥櫭琻鈥� k鈥檌igh猫鈥� vich霉鈥� pH < 4 n矛lii gik鈥檌tr鈥檃anjik. Aii n矛n鈥� nagwidadhat 214 ts鈥櫭爐 4993 ezhik t鈥檌inch鈥櫭光��. Vizh矛t nih艂inehch鈥檌鈥� goo鈥檃ii tr鈥檌gwinah鈥檌n鈥� k鈥檌igh猫鈥� j霉k gweendoo aii nan gwiiyeendoo gwiltraa gik鈥檌tr鈥檃anjik.

Patterson, R.T., et al. 2022. End-member mixing analysis (EMMA) as a tool for the detection of major historic storms in lake sediments. Paleoceanography and Paleoclimatology. 37 (11), e2022PA004510. https://doi.org/10.1029/2022PA004510

Major Tropical Cyclone (TC) events cause extensive damage in coastal regions of the western North Atlantic Basin. The short instrumental record leaves significant gaps in understanding long-term trends in TC recurrence and intensity, creating uncertainty about future storm trends. Analysis of an 鈭�520-year core record from Harvey Lake, located >80 km from the Atlantic coast in southwestern New Brunswick, Canada was carried out using: 1) End Member Mixing Analysis (EMMA) of lake sediment grain size data to identify storm-linked sedimentological processes; and 2) ITRAX XRF derived element/ratios (Fe, Ti, Ca/Sr, Zr/Rb, K/Rb, Br+Cl/Al) associated with precipitation, weathering, catchment runoff and air masses. Three derived end members were correlated to heavy rainfall events (EM01), spring freshet (EM02), and TCs (EM03). CONISS analysis of the EMMA and XRF core data resulted in recognition of four unique climatic zones distinguished by distinct distributions of TC and rainfall/ weathering/ runoff/ and air masses. Numerous, major (EM01) rainfall events and (EM03) TC events characterized the basal core record during the early Little Ice Age (LIAa; Zone 1) phase, terminating at 鈭�1645. A near cessation of heavy rainfall and TC events differentiated the subsequent colder LIAb (鈭�1645-1825; Zone 2) and subsequent Little Ice Age Transition (鈭�1825-1895; Zone 3) . A resurgence of major rainfall and TC events occurred during recovery from the LIA starting in 鈭�1895 (Zone 4). EMMA provides a robust tool for recognition of TC and major rainfall events, and greatly expands the potential for paleo-storm activity research well inland from coastal regions.

Moore, et al. 2022. The appendicular myology of Stegoceras validum (Ornithischia: Pachycephalosauridae) and implications for the head-butting hypothesis. PLoS ONE 17(9): e0268144. https://doi.org/10.1371/journal.pone.0268144

In this study, we use an exceptional skeleton of the pachycephalosaur Stegoceras validum (UALVP 2) to inform a comprehensive appendicular muscle reconstruction of the animal, with the goal of better understanding the functional morphology of the pachycephalosaur postcranial skeleton. We find that S. validum possessed a conservative forelimb musculature, particularly in comparison to early saurischian bipeds. By contrast, the pelvic and hindlimb musculature are more derived, reflecting peculiarities of the underlying skeletal anatomy. The iliotibialis, ischiocaudalis, and caudofemoralis muscles are enlarged, the last having a greater leverage owing to the distal displacement of the fourth trochanter along the femur. These larger muscles, in combination with the wide pelvis and stout hind limbs, produced a stronger, more stable pelvic structure that would have proved advantageous during hypothesized intraspecific head-butting contests. The pelvis may have been further stabilized by enlarged sacroiliac ligaments, which stemmed from the unique medial iliac flange of the pachycephalosaurs. Although the pubis of UALVP 2 is not preserved, the pubes of other pachycephalosaurs are highly reduced. The puboischiofemoralis musculature was likely also reduced accordingly, and compensated for by the aforementioned improved pelvic musculature.

Patterson, R.T., 2022. A 520-year paleolimnological grain size and ITRAX record from Harvey Lake, New Brunswick, Canada. Dryad,听

This grain size data was derived from a 250 mm long gravity Glew Maxi core (HL-2017-GC-2) collected from near the mouth of Herbert’s Cove, Harvey Lake, New Brunswick Canada (45掳43鈥�42.535鈥漀; 67掳01鈥�23.739鈥漌) at a water depth of 4.5 m. The core was subsampled on site at 2 mm resolution using a Glew core extruder before transport to 杏吧原创 University for subsequent analysis. Subsamples were analyzed using a Beckman Coulter LS 13 320 laser diffraction grain size analyzer equipped with a universal liquid module. The resultant triplicate grain size data were averaged using a script within Matlab which generated the data archived here. Subsequent radiocarbon dating revealed that deposition spanned the last 520 years of deposition..

Walsh, C.R., Patterson, R.T. 2022. Regional impact of large-scale climate oscillations on ice out variability in New Brunswick and Maine. PeerJ. 10:e13741

The available ice out (the date of disappearance of ice from a water body) recordswere analyzed from four relatively closely spaced lakes in southwestern New Brunswick (Harvey, Oromocto, Skiff) and eastern Maine (West Grand Lake), with the longest set of available observations being for Oromocto Lake starting in 1876. Results of a coherence analysis carried out on the ice out data from the four lakes indicates that there is regional coherence and correspondingly, that regional drivers influence ice out. These results also indicate that ice out dates for lakes from the region where records have not been kept can also be interpolated from these results. As the ice out record was coherent, further analysis was done for only Oromocto Lake on the basis of it having the longest ice out record. Cross-wavelet analysis was carried out between the ice out record and a variety of cyclic climate teleconnections and the sunspot record to identify which phenomena best explain the observed ice out trends. The most important observed contributors to ice out were the North Atlantic Oscillation (NAO) and the El Ni帽o Southern Oscillation (ENSO), with observed periodicities at the interannual scale. At the decadal scale the Pacific Decadal Oscillation (PDO) and the 11-year solar cycle were the only patterns observed to significantly contribute to ice out.

Walsh, C.R., Patterson, R.T. 2022. Attribution of Observed Periodicity in Extreme Weather Events in Eastern North America. Earth and Space Science. 9, e2022EA002359. https://doi.org/10.1029/2022EA002359

Instrumental weather records (1880鈥�2020s) from eastern North America were analyzed to characterize the regional patterns and drivers of seasonal extreme weather (snow, rain, high and low temperatures). Using agglomerative hierarchical clustering of extreme weather data, the region was divided into three subregions that are influenced by coastal-marine gradients and latitudinal factors. Subsequent analyses were performed on high-quality stations from each subregion and results compared between one another. Long-term locally weighted linear regressions delineated long-term changes in extreme weather, and a combination of spectral analysis, continuous wavelet transforms, and cross wavelet transforms were used to identify periodic components in the data. Regional extreme weather is generally periodic, composed of interannual to interdecadal-scale oscillations and driven by several natural climatic oscillations. The most important such oscillation is the 11-year Schwabe Solar Cycle, which has a strong and continuous effect on regional extreme weather. The Pacific Decadal Oscillation and Quasi Biennial Oscillation also show considerable influence, but intermittently. The El Ni帽o Southern Oscillation, the Arctic Oscillation, and the North Atlantic Oscillation all have a weaker but interrelated influence. While the Atlantic Multidecadal Oscillation showed the weakest overall influence on regional extreme weather, it demonstrated a clear spatial gradient across the region, unlike the aforementioned oscillations. Long-term changes in regional extreme weather are not generally important, in that a sustained increase or decrease in extreme weather events is not usually characteristic of the weather records. The primary exception to this result is for extreme minimum temperature events, whose frequency has slightly decreased since the 1880s.

Atasiei et al. 2022. Impact of Post-Tropical Storm Arthur on benthic Arcellinida assemblage dynamics in Harvey Lake, New Brunswick, Canada. Hydrobiologia. 849 (13): 3041-3059. https://doi-org.proxy.library.carleton.ca/10.1007/s10750-022-04912-x

Arcellinida (testate lobose amoebae) were examined in surface-sediment samples collected in 2015 from throughout Harvey Lake, New Brunswick, Canada to assess whether the passage of Post-Tropical Storm Arthur in 2014 impacted the distribution of taxa and assemblages. Cluster analysis and non-metric multidimensional scaling (NMDS) revealed four distinct arcellinidan assemblages. Redundancy Analysis (RDA) and partial-RDA results were used to identify four variables that significantly influenced the assemblage composition and explained 20.2% of the faunal distributional variability. Arsenic concentration in the sediments of Harvey Lake is an important control over the distribution of Arcellinida assemblages. Shallower water (less than median water depth of 3.56 m) and highly diverse assemblages A3 and A4 (median SDI = 2.6) significantly correlated with wind-mixing probability , while deeper water (greater than median = 6.2 m) and moderately to highly diverse assemblages A1 and A2 (SDI range 2.4 鈥� 2.7) associated strongly with EM2. End Member 2 was derived from the suspension of and redeposition of sediments when the storm water wave base was deepened during the passage of Arthur. Water depth of sampling stations should be taken into consideration in lakes that may be periodically impacted by large storms.

Wyenberg-Henzler et al. 2022.听 Ontogenetic dietary shifts in North American hadrosaurids. Cretaceous Research 135: 105177, 15. p. https://doi.org/10.1016/j.cretres.2022.105177

Ontogenetic niche shifts, the phenomenon whereby animals change their resource use with growth, were probably widespread in dinosaurs, but most studies of duck-billed dinosaur ontogeny have so far focused mainly on the development of the cranial ornamentation. Here, we quantify allometry of 13 ecomorphological variables of the skull and examine tooth microwear in a sample of North American hadrosaurids to better understand their ecological functioning with growth. Our results indicate that, consistent with the Jarman-Bell principle relating body size to fibre intake and feeding selectivity, juvenile hadrosaurids were relatively more selective than their adult counterparts and subsisted on softer, low-growing browse cropped using lateral rotations of the neck. Chewing movements of the jaw probably did not differ greatly between growth stages. Our findings invite further investigation relating to cranial ontogenetic allometry in hadrosauromorphs more broadly, and to the possible role of ontogenetic niche shifts in the size structuring of Late Cretaceous herbivore communities.

Walsh, C.R. and Patterson, R.T. 2022.听 Precipitation and temperature trends and cycles derived from historical 1890-2019 weather data for the City of Ottawa, Ontario, Canada. Environments. 9, 35, https://doi.org/10.3390/environments9030035

Patterson, R.T., et al. 2022. A portable extruder for precision high-resolution subsampling of unconsolidated cores. Journal of Paleolimnology.67 (2): 183-189. https://doi.org/10.1007/s10933-021-00203-y

We developed a portable extruder for precise and accurate high-resolution subsampling of unconsolidated sediment cores. This extruder is capable of producing subsamples at a minimum 1-mm resolution and is designed for easy operation and maintenance in the field. Movement of the threaded extruder rod (鈥欌�� 8 start acme thread) through the core barrel is driven by a crank wheel graduated in 1-mm increments. This extruder design is particularly useful for obtaining incremental subsamples for applications where high-resolution subsamples of identical size are required (e.g. time series analysis, climate variability, land use change, contamination), and for use in field settings where it is impractical to deploy a freeze corer.

Miller, C.B., et al. 2022. Mediation of arsenic mobility by organic matter in mining-impacted sediment from sub鈥怉rctic lakes: Implications for environmental monitoring in a warming climate. Environmental Earth Sciences 81, 137. https://doi.org/10.1007/s12665-022-10213-2

Arsenic (As) is sequestered at the sediment-water interface (SWI) in mining-impacted lakes through adsorption and/or co-precipitation with authigenic iron (Fe)-(oxy)hydroxides or sulphides. The results of this study demonstrate that the accumulation of solid phase organic matter (OM) in near-surface sediments also influences the mobility and fate of As in lakes of northern Canada. Sediment gravity cores, sediment grab samples, and porewaters were collected from three lakes downstream of the former Tundra gold mine, Northwest Territories. Analysis of sediment using combined micro-X-ray fluorescence/diffraction, K-edge X-ray Absorption Near-Edge Structure (XANES), and organic petrography shows that As is associated with both aquatic (benthic and planktonic alginate) and terrestrially-derived organic matter (roots and bark; cutinite; funginite). Most As is hosted by fine-grained Fe-(oxy)hydroxides or sulphide minerals (e.g., goethite, ferrihydrite, orpiment, lepidocrocite, pyrite, mackinawite); however, grain-scale synchrotron-based analysis shows that As is also associated with amorphous solid phase OM. Mixed As oxidation states in porewater (median = 62 % As (V), 18 % As (III); n = 20) and sediment (median = 80 % As (-I) and (III), 19 % As (V); n = 9) indicate the presence of variable redox conditions in the near-surface sediment and suggest that post-depositional remobilization of As has occurred. Detailed characterization of As-bearing OM at and below the SWI suggests that this material plays an important role in stabilizing redox-sensitive authigenic minerals (i.e. sulphides and Fe-(oxy)hydroxides), and associated As, in the near-surface sediment. Based on the results of this study, we expect that increased concentrations of aquatic and terrestrially-derived labile OM will drive post-depositional surface-enrichment of As in mining-impacted lakes and may mediate the diffusion of dissolved As to overlying surface waters.

Wyenberg-Henzler, T., et al. 2022.

Size-mediated competition and community structure in a Late Cretaceous herbivourous dinosaur assemblage. Historical Biology, 34 (10): 2230-2240. https://doi-org.proxy.library.carleton.ca/10.1080/08912963.2021.2010191

Gushulak, C., et al. 2022. Siliceous algae response to the ‘Great Acceleration鈥� of the mid-twentieth century in Crawford Lake (Ontario, Canada): a candidate for the Anthropocene GSSP. Anthropocene Review.听9 (3), 571-590. https://doi.org/10.1177/20530196211046036

Diatom and chrysophyte assemblages from varved sediments of meromictic Crawford Lake, Ontario record major environmental changes resulting from spatially broadening anthropogenic environmental stressors related to the 鈥楪reat Acceleration鈥� in the mid-twentieth century. Biannual assessment of diatom and chrysophyte assemblages over the last ~200 years allowed for rate of change analysis between adjacent samples that increased substantially during the mid-twentieth century, concurrent with significant generalized additive model trends. Changes in diatoms and chrysophyte assemblages were likely driven by multiple anthropogenic stressors including local forestry harvesting, agriculture, and milling activities, acidic deposition from regional industrial processes, and anthropogenic climate warming. Novel siliceous algal assemblages now exist in Crawford lake, likely related to the complexities of the above mentioned local and regional stressors. The major assemblage changes at the proposed base of the Anthropocene Epoch detected in this study supports the laminated sequence from Crawford Lake as a candidate for the Anthropocene GSSP.

Nasser, N.A., et al. 2021. Erugomicula, a new genus of Arcellinida (testate lobose amoebae). Palaeontologia Electronica. 24.1.a16. https://doi.org/10.26879/807

Testate lobose amoebae of the order Arcellinida are a diverse, cosmopolitan group of shelled protists found in many environments, including freshwater habitats, peatlands and soils. Their decay-resistant tests make them an important fossil group for reconstructing Quaternary environments. Within the family Difflugidae Stein, 1859 more than 300 species and 200 sub-species have been attributed to the genus Difflugia Leclerc, 1815. Although carried out on only a few taxa, molecular evidence has demonstrated that test morphology is more important than test composition in categorizing distinct taxa within the Arcellinida. The type species of Difflugia, D. proteiformis Lamarck, 1816, is characterized by a terminal aperture and an elongate acuminate test. The morphology of D. proteiformis is vastly different from most other species assigned to Difflugia, explaining its polyphyletic status. We reclassify Difflugia bidens Penard, 1902 as type species of Erugomicula, a new genus within the Difflugidae, which is distinguished from other taxa within Difflugia by its broad, ovoid test, and distinct compression. Based on the compressed morphology of the test, which is not a characteristic of the Difflugiidae, we tentatively assign Erugomicula to the family Hyalospheniidae.

Hamilton, P.B., et al. (In Press) Late Holocene Diatom Community Response to Climate Driven Geochemical Changes in a Small, Subarctic Lake, Northwest Territories, Canada. The Holocene. 31 (7): 1124-1137. https://doi.org/10.1177/09596836211003214

Diatoms preserved in sediments between ~2850-200 cal BP in Pocket Lake, Northwest Territories, Canada, were analyzed. Five changes in diatom assemblages, were integrated with element, particle size and productivity to reconstruct past limnological conditions. An increase in the planktic community (Lindavia, Discotella, Cyclotella) and a shift to more acid tolerant diatom assemblages occur through time. The oldest assemblage (2860-2260 cal BP) is dominated by alkaliphile taxa, most notably, the araphid Staurosira venter and raphid Nitzschia alpina. This assemblage shows a relationship with sedimentary calcium, a driver of alkalinity. The uppermost two assemblages are linked to the Little Ice Age (ca. 800-200 cal BP) and the Medieval Climate Anomaly (ca. 1100-800 cal BP). The transitions to these upper assemblages began following deposition of the White River Ash (1100 cal BP) with an increase in larger particulates (56.6 mm) autothochonous inputs associated with enhanced runoff. With the decline of large particulates there was an assemblage transition into the LIA and a return of plankton. Lake productivity declined from 600-200 cal BP as indicated by Rock-Eval S2 trends. Throughout the 2800 years, ten discrete peaks in the concentration of sedimentary Cu, Pb and Zn were distinct and not linked to particulates. These increases are attributed to soluble metal mobility from catchment soils through enhanced seepage and spring snowmelt (heavy periods of snow accumulation). The more prominent metal spikes are linked to increases in Brachysira microcephala, an acid tolerant听 taxon. Anthropogenic contamination of As and Sb in the uppermost interval of the sediments highlights mobility problems of metal(loid)s in sediments. Organic matter in Pocket Lake was not affected by cyclic climate drivers originating from the NE Pacific, but identified trending changes in diatom composition associated with lake pH, tephra deposition, patterns of runoff associated with regional weather and climate variations.

Riou, L., et al. 2021. Lacustrine Arcellinida (Testate Lobose Amoebae) as bioindicators of arsenic concentration within the Yellowknife City Gold Project, Northwest Territories, Canada. Limnologica. 87 (March): 125862. https://doi.org/10.1016/j.limno.2021.125862

Arcellinida (testate lobose amoebae) were examined in near-surface sediment samples from 30 lakes located within the Gold Terra Resource Corporation (GTRC) Yellowknife City Gold Project, Northwest Territories, Canada, to assess the applicability of using the group as a robust tool to assess Arsenic (As) contamination. Lake contamination by As is of concern in the Yellowknife area because it is derived from geogenic (bedrock) and anthropogenic sources (legacy pollution from former mining operations, particularly the Giant Mine [1948鈥�2004]). Statistical multivariate analyses (cluster analysis, non-metric multidimensional scaling [NMDS], and redundancy analysis [RDA]) were performed on geochemical (inductively coupled plasma mass spectrometry [ICP-MS]) and organic (loss on-ignition) data to identify geochemical and hydrogeological controls on the arcellinidan distribution in the lakes. Three distinct faunal assemblages were identified using Cluster analysis and NMDS: 1) Elevated Arsenic Assemblage (EAA; Approximately Unbiased (AU) p -value = 97%; median As = 272.4 mg/kg, range = 42鈥�1353 mg/kg ; n = 9); 2) Centropyxid- Dominated Assemblage (CDA; AU p -value = 87%; median As = 169.7 mg/kg, range 60鈥�233 mg/kg ; n = 9); and, 3) Difflugiid Dominated Assemblage (DDA; AU p -value = 95%; median As = 61.3 mg/kg, range = 16鈥�316 mg/kg ; n = 12). Six statistically significant controls on assemblage structure were identified using RDA. These were As, calcium, iron, strontium, water depth, and total organic carbon (Arcellinida variance explained = 36.2%) 鈥� As is the most significant control (12.2%; p-value < 0.002). Stress-tolerant centropyxids dominate in lakes characterized by elevated sedimentary As concentrations (64% centropyxids in EAA; 40% centropyxids in CDA), while stress sensitive taxa thrived in samples associated with lower As concentrations (DDA). Our results corroborate the findings of previous Arcellinida studies in subarctic Canada and confirms the reliability of using Arcellinida as a reconnaissance tool for tracking As contamination in impacted lakes.

Gregory, B.R.B.G. et al., 2021. The impact of cyclical, multi-decadal to centennial climate variability on arsenic sequestration in lacustrine sediments. Palaeogeography, Palaeoclimatology, Palaeoecology. 565 (March): 110189, 14 pp., https://doi.org/10.1016/j.palaeo.2020.110189

Examining paleoclimate-driven changes of elemental contaminants, such as Arsenic (As), increases the understanding of the mobility and fate of elements under a warming climate scenario. To examine variability in As sequestration in the sediments of a freshwater system in response to decadal- to centennial-scale climate oscillations, a freeze-core was recovered from Control Lake, Northwest Territories (64.07 掳N, -111.13掳W). Radiocarbon dating of bulk organic sediments provided a basal age of ca. 3300 calibrated years BP for the core. Sediment geochemistry was determined using Itrax Xray fluorescence core-scanning (Itrax-XRF). Elemental concentrations were measured on a sub-set of samples using ICP-MS after multi-acid (MA) digestion to assess the accuracy of Itrax-XRF results. Comparison of Itrax-XRF to ICP-MS using ItraXelerate software show Pearson鈥檚 R 2 values > 0.75, with the exception of As (R 2 = 0.44). Calibrated Itrax-XRF elemental data were centered log-ratio transformed (CLR) to eliminate issues related to data closure. Proxies for sediment particle size (Ti CLR , K CLR ) and As concentration (As CLR) were examined for response to quasi-periodic climate oscillations using spectral and wavelet analyses. Significant periodicities (>0.95 confidence interval) were observed with approximately 4鈥�16, 30鈥�60, 90鈥�120, and 160鈥�280 yr. periods in all elemental records. These frequencies are interpreted as corresponding to El Ni帽o/Southern Oscillation, the North Atlantic Oscillation, and/or 11-yr. sunspot cycles, 30鈥�60-yr. Pacific Decadal Oscillation, and centennial-scale solar cycles (e.g., 90-yr. Gleissberg cycle; 205-yr. Suess cycle). Coeval occurrence of these periodicities revealed through wavelet analysis of Control Lake geochemistry data suggests that these climate cycles only impact Control Lake when in-phase with one another. Moderate-strength negative correlations between As CLR and K CLR (Spearman鈥檚 蟻 = -0.38, p-value < 0.001, n = 785), and As CLR and Ti CLR , (Spearman鈥檚 蟻 = -0.52, p-value < 0.001, n = 785) suggest that As is primarily sequestered in sediments during intervals of warmer temperatures and higher productivity.

Patterson, C.W. and Ernst, R.E. 2020. A novel geomatics method for assessing the Haughton impact structure. Meteoritics & Planetary Science 1鈥�13. doi: 10.1111/maps.13573-3267.

Terrestrial impact structures are typically modified by erosion, burial, and tectonic deformation. Their systematic morphologies are typically reconstructed through a combination of geological and topographic mapping, satellite imagery, and geophysical surveys. This study applies a novel geomatics approach to assessment of the morphology of the extensively studied Haughton impact structure (HIS), Devon Island, Nunavut, in order to test its potential to improve the accuracy and quality of future impact structure reconstruction. This new methodology integrates HIS lithological data, in the form of digitized geologic mapping, with a digital elevation model, within diametrically opposed, wedge-shaped couplets, and plots these data as pseudo cross sections that capitalize on the radial symmetry of the impact structure. The pseudo cross sections provide an accurate reconstruction of the near- surface stratigraphic sequences and terraces in the faulted annulus of the modified crater rim. The resultant pseudo cross sections support current interpretations regarding the 10鈥�12 km diameter of the transient cavity, and successfully reproduce the visible outer ring and intermediate uplifted zone within the central basin. Observed positions of vertical offsets suggest that the extent of impact deformation extends beyond the current estimates of the apparent crater rim to radial distances of between 14 and 15 km. Finally, the new geomatics approach provides an improved determination of the spatial, stratigraphic, and temporal relationships among the Haughton Formation lake sediments, allochthonous crater-fill impactites, and uplifted target rocks, and indicates that there was a not-insignificant time gap between the formation of the impact structure.

Patterson, R.T., et al. 2020. A novel protocol for mapping the spatial distribution of storm derived sediment in lakes. SN Applied Sciences 2:2125. https ://doi.org/10.1007/s4245 2-020-03908 -3

A novel geomatics methodology is presented for locating optimal lake coring sites to potentially capture evidence of paleo-storms. One hundred sediment-water interface samples collected from Harvey Lake, NB, Canada (45掳43鈥�45鈥砃; 67掳00鈥�25鈥砏 ) were analyzed using: end member mixing analysis (EMMA), which can be used to recognize modal grain size distributions derived from sediment resuspension during major storms; and Itrax x-ray fluorescence core scanning-derived Ti, an indicator of catchment runoff, which is enhanced during major storm events. Geospatial models based on lake bathymetric and historical wind speed data ( Fredericton INTL A climatological station; 1953-2015) were used to determine lake bottom areas susceptible to wave base sediment resuspension. EMMA End Member (EM) 02 (mode=40 渭m) was widely distributed in areas > 4.4. m water depth, which have been unimpacted by wave base remobilization since 1953. Deposition of EM 02 in deeper water areas was interpreted to be of major storm derivation, the result of fallout of resuspended sediments from the water column. This EM was most concentrated in the central part of the lake at >6 m water depth, as well as at the z-max (~11m), and in Herbert鈥檚 Cove (3-6 m). The main source of run-off derived Ti into the lake was through Sucker Brook, with the highest concentrations in Herbert鈥檚 Cove and the central part of the lake, including the lake z-max. This assessment indicates that the best undisturbed sedimentary record of paleo-storms is mostly likely in the central part of the lake north of the z-max at water depths of >6 m, as well as deeper water areas of Herbert鈥檚 Cove.

Marcisz, K. et al. 2020.听Testate amoebae functional traits and their use in paleoecology Frontiers in Ecology and Evolution. https://doi.org/10.3389/fevo.2020.575966

This review provides a synthesis of current knowledge on the morphological and functional traits of testate amoebae, a polyphyletic group of protists commonly used as proxies of past hydrological changes in paleoecological investigations from peatland, lake sediment and soil archives. A trait-based approaches to understanding testate amoebae ecology and paleoecology has gained in popularity in recent years, with research showing that morphological characteristics provide complementary information to the commonly used environmental inferences based on testate amoeba (morpho-)species data. We provide a broad overview of testate amoeba morphological and functional traits and trait-environment relationships in the context of ecology, evolution, genetics, biogeography, and paleoecology. As examples we report upon ecological and paleoecological studies that have use trait-based approaches, and describe key testate amoeba traits that can be used to improve the interpretation of environmental studies. We also highlight knowledge gaps and speculate on potential future directions for the application of a trait-based approaches in testate amoebae research.

Nasser et al.听 2020. Intra-lake response of Arcellinida (testate lobose amoebae) to gold mining-derived arsenic contamination in northern Canada: Implications for environmental monitoring. PeerJ.

Arcellinida (testate lobose amoebae) were examined from 40 near-surface sediment samples (top 0.5 cm) from two lakes impacted by arsenic (As) contamination associated with legacy gold mining in subarctic Canada. The objectives of the study are two folds: quantify the response of Arcellinida to intra-lake variability of As and other physicochemical controls, and evaluate whether the impact of As contamination derived from two former gold mines, Giant Mine (1938鈥�2004) and Tundra Mine (1964鈥�1968 and 1983鈥�1986), on the Arcellinida distribution in both lakes is comparable or different. Cluster analysis and nonmetric multidimensional scaling (NMDS) were used to identify Arcellinida assemblages in both lakes, and redundancy analysis (RDA) was used to quantify the relationship between the assemblages, As, and other geochemical and sedimentological parameters. Cluster analysis and NMDS revealed four distinct arcellinidan assemblages in Frame Lake (assemblages 1鈥�4) and two in Hambone Lake (assemblages 5 and 6): 1) Extreme As Contamination (EAC) Assemblage; 2) High calcium (HC) Assemblage; 3) Moderate As Contamination (MAC) assemblages; 4) High Nutrients (HN) Assemblage; 5) High Diversity (HD) Assemblage; and, 6) Centropyxis aculeata (CA) Assemblage. RDA analysis showed that the faunal structure of the Frame Lake assemblages was controlled by five variables that explained 43.2% of the total faunal variance, with As (15.8%), Olsen phosphorous (Olsen-P; 10.5%), and Ca (9.5%) being the most statistically significant (p < 0.004). Stress-tolerant arcellinidan taxa were associated with elevated As concentrations (e.g. EAC and MAC; As concentrations range = 145.1鈥�1336.6 mg.kg-1; n = 11 samples), while stress-sensitive taxa thrived in relatively healthier assemblages found in substrates with lower As concentrations and higher concentrations of nutrients, such as Olsen-P and Ca (e.g. HC and HM; As concentrations range = 151.1鈥�492.3 mg.kg-1; n = 14 samples). In contrast, the impact of As on the arcellinidan distribution was not statistically significant in Hambone Lake (7.6%; p-value = 0.152), where the proportion of silt (24.4%; p-value = 0.005) and loss-on-ignition-determined minerogenic content (18.5%; p-value = 0.021) explained a higher proportion of the total faunal variance (58.4%). However, a notable decrease in arcellinidan species richness and abundance and increase in the proportions of stress-tolerant fauna near Hambone Lake鈥檚 outlet (e.g., CA samples) is consistent with a spatial gradient of higher sedimentary As concentration near the outlet, and suggests a lasting, albeit weak, As influence on Arcellinida distribution in the lake. We interpret differences in the influence of sedimentary As concentration on Arcellinida to differences in the predominant As mineralogy in each lake, which is in turn influenced by differences in ore-processing at the former Giant (roasting) and Tundra mines (free-milling).

Nasser et al.听 2020. Use of Arcellinida (testate lobose amoebae) Arsenic tolerance limits as a novel tool for biomonitoring Arsenic contamination in lakes. Ecological Indicators.
113 (June): 106177. https://doi.org/10.1016/j.ecolind.2020.106177

Arsenic (As)-tolerance of Arcellinida (testate lobose amoebae) bioindicators in lake sediments (n 121 = 93) in subarctic Northwest Territories, Canada was investigated. Legacy As contamination from gold mining poses an emerging threat to lake biota due to climatic warming that may increase As bioavailability in lake waters. The geospatial extent of legacy As contamination related to the former Giant Mine (Yellowknife) was delineated. Five Arcellinida assemblages correlated strongly with ten variables (variance explained = 40.4%), with As (9.4%) and S1-carbon (labile organic matter; 8.9%) being the most important (p-value = 0.001). Stressed assemblages characterized proximal lakes <10 km from the former mine site, consistent with a recently identified, geochemically based zone of high As-impact. We propose that bioavailable As (As2O3, As+3) influences the spatial distribution of nutrient-sensitive Arcellinida through suppression of preferred microbial food sources. Three As-sensitive arcellinidan groups were identified: Low Tolerance Group (As=0-350ppm); Moderate Tolerance Group (As=350-760 ppm); and, High Tolerance Group (As>750 ppm). We conclude that Arcellinida distribution in As contaminated lakes can provide insight into the relative abundance of bioavailable vs inert As species, a metric not captured using industry standard ICP-MS. Lakes with As-stressed arcellinidan faunas and high As concentrations may then be targeted for more expensive As speciation geochemical analysis to provide requisite data for remediation or mitigation strategies.

Cockburn et al.听 2020. Intra-lake Arcellinida (testate lobose amoebae) response to winter de-icing contamination in an eastern Canada road-side 鈥楽alt Belt鈥� lake. Microbial Ecology. 80: 366-383. https://doi.org/10.1007/s00248-020-01513-w

Salt contamination of lakes, due to the application of winter de-icing salts on roads, presents a significant environmental challenge in the 鈥榮alt belt鈥� region of eastern North America. The research reported here presents the first deployment of a newly developed proxy tool based on Arcellinida (testate lobose amoebae) for monitoring road salt contamination. The research was conducted at Silver Lake in Eastern Ontario, a 4-km long lake with the heavily-travelled Trans-Canada Highway (HWY 7) transiting the entire southern shore. The lake showed elevated conductivity (297-310 渭S/cm) and sub- brackish conditions (0.14-0.15 ppt). Sodium levels were also elevated near the roadside (median Na = 1020 ppm). Cluster analysis and nonmetric multidimensional scaling results revealed four distinct Arcellinida assemblages: 鈥淢oderate-Depth Assemblage (MDA)鈥�, 鈥淒eep Water Assemblage (DWA)鈥�, both from below the 8 m thermocline, and the shallower water 鈥淪hallow Low Sodium Assemblage (SLSA)鈥�, and 鈥淪hallow High Sodium Assemblage (SHSA)鈥�. Redundancy analysis showed a significant response of Arcellinida to road salt contamination in shallower areas of the lake, with confounding variables significantly impacting assemblage distribution beneath the thermocline (e.g. water temperature, water depth, sediment runoff from catchment [Ti], sediment geochemistry [Ca, S]). The results of this study indicate that the trophic structure of the lake has to date only been modestly impacted the cumulative nature of road salt contamination. Nonetheless the Silver Lake results should be considered of concern and warrant continued arcellinidan biomonitoring to gauge the ongoing and long-term effects of road salt on its ecosystem.

Steele et al. 2020. Assessment of FlowCam technology as a potential tool for rapid semi-automatic analysis of lacustrine Arcellinida (testate lobose amoebae). Environmental Technology & Innovation 17: 100580. https://doi.org/10.1016/j.eti.2019.100580.

This study assessed the possibility of replacing conventional microscopic methods of species-level identification and quantification of Arcellinida with a more rapid method utilizing the FlowCam with VisualSpreadsheet (FCVS; Fluid Imaging Technologies, Inc.). Arcellinida are an established group of benthic bioindicators of water and sediment quality in lakes. The use of Arcellinida proxy analysis in lakes and peatlands has dramatically increased since the 1980s, but the labor-intensive nature of identifying and quantifying Arcellinida through microscopy limits the number of samples analysed. A flow cytometer and microscope with machine learning software has been used to enhance the speed of micropaleontological analysis for some groups (e.g., diatoms), but the potential of using the instrument to analyze Arcellinida in lake sediments has not previously been assessed. The FCVS was assessed here as a method of rapidly analyzing Arcellinida by comparing the results obtained by FCVS with results previously obtained through conventional microscopy in a 2016 study, using the same 46 sediment-water interface samples collected from three quadrats (1鈥�3) in Wightman Cove, Oromocto Lake, New Brunswick, Canada. The FCVS was found to be most suitable for categorizing taxa as morpho-groups rather than using conventional taxonomic species. Therefore, results of the 2016 study were reclassified at the morphological level to facilitate comparison. Results of cluster analysis and Bray-Curtis dissimilarity matrix (BCDM) analysis showed that arcellinidan assemblages obtained through conventional microscopy and FCVS were comparable. Analysis using FCVS reduced operator analysis time by approximately 45%. FCVS shows potential as a reliable method for more rapid analysis of lacustrine Arcellinida, particularly for very large sample data sets; however, FCVS technology can only resolve Arcellinida at the morphological level, meaning that conventional microscopy methods are required if finer species-level taxonomic results are required.

Nasser, N.A., Gregory, R.B., Steele, R.E., Patterson, R.T., Galloway, J.M., 2020. Behind the organic veil: assessing the impact of chemical deflocculation on organic content reduction and lacustrine Arcellinida (testate amoebae) analysis. Microbial Ecology. 79: 443-458. https://doi.org/10.1007/s00248-019-01429-0

Arcellinida (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路贬₂O), potassium hydroxide (KOH), or Calgon庐 ((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 Calgon庐 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鈥�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 Calgon庐 treatments resulted in marginal organic matter reduction and caused severe damage to the arcellinidan tests.