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Chrysophyte cysts preserved in recent and pre-industrial lake sediment samples from 54 Muskoka-Haliburton (Ontario) lakes were used in a paleolimnological study to determine the impact of acidic precipitation and cottage development on water quality. A total of 246 cyst morphotypes were identified. Ecological preferences of cyst morphotypes were de...
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... (Hill, 1979) separated the cysts into four primary groups and further into a subset of eight groups (Figure 3). TWINSPAN is a clustering method which uses similarity measures based on Correspond- ence Analysis (CA) to uncover the hierarchial structure present in species data ( Jongman et al., 1995) The four primary cyst groups are shown on the RDA plot ( Figure 2). ...
Context 2
... phylogenetic basis of TWINSPAN divisions (Figure 3) was determined by examining the biological affinities, where known, of the cysts in each group (Table 3) (Preisig, 1995). Cysts in the Mallomonadaceae family, class Synurophyceae, appeared to occur primarily in groups 1 and 2. The Synuraceae family, also class Synurophyceae, was dominant in group 3a, with little representation of this class seen in groups 3b and 4a. ...
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Citations
... Chrysophyte cysts naming and classification are based on their characteristic shapes, pores [4], collars [4], and ornamentation [8] observed under SEM [3]. Chrysophyte cysts are generally indicators of environmental reconstruction in modern lake sediments [9,10]. Zhang et al. (2016) were the first to report and describe the morphological characteristics of the chrysophyte cyst fossils in the Triassic Yanchang Formation in the Ordos Basin [8]. ...
... [2], Western United States [3], northern Poland [5], Finland [6], northwestern Mediterranean region [7], Muskoka Haliburton region [9], Northeast Spain [10], and northeast China [39]. But, chrysophyte cyst fossils were first discovered in the Triassic Yanchang Formation, Ordos Basin, China [8]. ...
... Guan et al. revealed the preservation of pyritized Chuaria in the Ediacaran shales, dominated by sedimentary organic matter content and bottom water redox condition [57]. However, chrysophyte cysts were characterized by siliceous structures, which were widely distributed in modern lake sediments in southwest Greenland [2], Western United States [3], northern Poland [5], Finland [6], northwestern Mediterranean region [7], Muskoka Haliburton region [9], Northeast Spain [10], and northeast China [39]. But, chrysophyte cyst fossils were first discovered in the Triassic Yanchang Formation, Ordos Basin, China [8]. ...
Chrysophyte cyst fossils were widely pyritized and preserved in black shales from the seventh member (Ch7 Mbr) of the Yanchang Formation in the Ordos Basin. The age, pyritization, and preservation model of these fossils have not been studied previously. In this study, the astronomical orbital cycles of the Ch7 Mbr were determined based on the gamma ray series of the Yan56 and Zhen 421 wells. An astronomical time scale (ATS) analysis revealed that the depositional duration of Ch7 Mbr was approximately 5 Ma. According to the 206Pb/238U radiometric dating of zircons using laser ablation inductively coupled plasma mass spectrometry (La-ICP-MS), the tuffs at the bottom of Ch7 Mbr were crystallized at 234 Ma, which served as a geological anchor. The ages of three submembers in Ch7 Mbr were estimated at 234.0–232.4 Ma, 232.4–230.8 Ma, and 230.8–229.1 Ma based on ATS analysis. In addition, chrysophyte cyst fossils were well preserved by pyritization in the Ch7 Mbr black shales. There were six types of microscopic morphologies with different pores, collars, and surface ornamentation under scanning electron microscopy (SEM). The age of the chrysophyte cyst fossils was at least 233.6 Ma in the Triassic Carnian Pluvial Episode (CPE) based on the 405 kyr tuned ATS. Moreover, the paleoredox conditions in Ch7 Mbr were reconstructed, and a preservation model of chrysophyte cyst fossils was established based on geochemical analyses. Fossil pyritization was caused by bacterial sulfate reduction near the water-sediment interface under suboxic to anoxic environmental conditions. Pyritization was initiated on the walls of the chrysophyte cysts by the formation of microcrystalline pyrite. Because of the gradual pyritization of the chrysophyte cyst wall, the organic matter in the interior of the fossil was well preserved.
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... For example, Holocene hydroseral succession of a polygonal peatland from a shallow lake to a Sphagnum peatland in Siberia was inferred using sedimentary stomatocysts and other proxies (Jasinski et al., 1998). Although there has been much progress in taxonomic and paleoenvironmental studies of stomatocysts in peaty environments, the use of stomatocysts as a proxy for environmental changes in peatlands has lagged far behind that in lakes (Brown et al., 1997;De Jong et al., 2016;Schmidt, 1996a, 1996b;Kamenik and Schimidt, 2005;Lotter et al., 1997;Pla and Catalan, 2005;Wilkinson et al., 1999). Given that stomatocysts have been found to be sensitive to changes in acidity and nutrients in aquatic environments (Zeeb et al., 1990;Betts-Piper et al., 2004), alterations in microhabitats of peatlands (e.g. ...
Peatlands are critical ecosystems in regulating global carbon cycle and hosting distinctive biodiversity. Chrysophyte stomatocysts, siliceous resting stages of golden-brown algae, are widely distributed in acidic and oligotrophic environments of peatlands. Presently, little knowledge is available on the composition and distribution
of stomatocysts in subtropical peatlands. This study investigated the communities of moss-inhabiting stomatocysts in three Sphagnum-dominated peatlands in central China, and their association with environmental variables. Fifty-nine stomatocyst morphotypes with two additional formae were identified according to the International Statospore Working Group guidelines, and stomatocyst assemblages were significantly different among the three peatlands. In addition, these stomatocyst morphotypes were classified into eight morphologybased functional groups according to morphological traits, such as types of collar and ornamentation. Redundancy
analyses revealed that stomatocyst assemblages at both morphotype- and functional group-level were significantly correlated with depth to water table, oxidation reduction potential, and morphotype-level composition was further related to electronic conductivity and potassium. Generally, cysts with a complex collar preferred dry hummocks, while large cysts with long spines mainly occurred in wet hollows. This study highlights the usage of chrysophyte stomatocysts as potential bioindicators for environmental changes in these subtropical peatlands, as well as similar peaty environments.
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... For example, Holocene hydroseral succession of a polygonal peatland from a shallow lake to a Sphagnum peatland in Siberia was inferred using sedimentary stomatocysts and other proxies (Jasinski et al., 1998). Although there has been much progress in taxonomic and paleoenvironmental studies of stomatocysts in peaty environments, the use of stomatocysts as a proxy for environmental changes in peatlands has lagged far behind that in lakes (Brown et al., 1997;De Jong et al., 2016;Schmidt, 1996a, 1996b;Kamenik and Schimidt, 2005;Lotter et al., 1997;Pla and Catalan, 2005;Wilkinson et al., 1999). Given that stomatocysts have been found to be sensitive to changes in acidity and nutrients in aquatic environments (Zeeb et al., 1990;Betts-Piper et al., 2004), alterations in microhabitats of peatlands (e.g. ...
Peatlands are critical ecosystems in regulating global carbon cycle and hosting distinctive biodiversity. Chrysophyte stomatocysts, siliceous resting stages of golden-brown algae, are widely distributed in acidic and oligotrophic environments of peatlands. Presently, little knowledge is available on the composition and distribution
of stomatocysts in subtropical peatlands. This study investigated the communities of moss-inhabiting stomatocysts in three Sphagnum-dominated peatlands in central China, and their association with environmental variables. Fifty-nine stomatocyst morphotypes with two additional formae were identified according to the International Statospore Working Group guidelines, and stomatocyst assemblages were significantly different among the three peatlands. In addition, these stomatocyst morphotypes were classified into eight morphologybased functional groups according to morphological traits, such as types of collar and ornamentation. Redundancy
analyses revealed that stomatocyst assemblages at both morphotype- and functional group-level were significantly correlated with depth to water table, oxidation reduction potential, and morphotype-level
composition was further related to electronic conductivity and potassium. Generally, cysts with a complex collar preferred dry hummocks, while large cysts with long spines mainly occurred in wet hollows. This study highlights the usage of chrysophyte stomatocysts as potential bioindicators for environmental changes in these
subtropical peatlands, as well as similar peaty environments.
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... Stomatocysts are chrysophyte vegetative cells with spherical siliceous walls, and they are diverse, widely-distributed and well-preserved in sediments (Wilkinson et al., 2001). Due to their sensitivity to changes in physicochemical conditions (Korkonen and Weckström, 2020), stomatocysts have been widely used to infer environmental changes including water pH Schmidt, 1996a, 1996b;Pla et al., 2003;Rybak et al., 1991;Wilkinson et al., 1999), salinity , nutrients (Wilkinson et al., 1999) and temperature (Pla and Catalan, 2005;De Jong and Kamenik, 2011;De Jong et al., 2013) in Canadian and European lakes. In comparison with lakes, peatlands are generally acidic and oligotrophic environments (Rotherham, 2020), which have been found to be favourable for chrysophytes that are more competitive algae in peaty conditions (Nicholls and Wuiek, 2015). ...
... For example, Holocene hydroseral succession of a polygonal peatland from a shallow lake to a Sphagnum peatland in Siberia was inferred using sedimentary stomatocysts and other proxies (Jasinski et al., 1998). Although there has been much progress in taxonomic and paleoenvironmental studies of stomatocysts in peaty environments, the use of stomatocysts as a proxy for environmental changes in peatlands has lagged far behind that in lakes (Brown et al., 1997;De Jong et al., 2016;Schmidt, 1996a, 1996b;Kamenik and Schimidt, 2005;Lotter et al., 1997;Pla and Catalan, 2005;Wilkinson et al., 1999). Given that stomatocysts have been found to be sensitive to changes in acidity and nutrients in aquatic environments (Zeeb et al., 1990;Betts-Piper et al., 2004), alterations in microhabitats of peatlands (e.g. ...
Peatlands are critical ecosystems in regulating global carbon cycle and hosting distinctive biodiversity. Chrysophyte stomatocysts, siliceous resting stages of golden-brown algae, are widely distributed in acidic and oligotrophic environments of peatlands. Presently, little knowledge is available on the composition and distri-bution of stomatocysts in subtropical peatlands. This study investigated the communities of moss-inhabiting stomatocysts in three Sphagnum-dominated peatlands in central China, and their association with environ-mental variables. Fifty-nine stomatocyst morphotypes with two additional formae were identified according to the International Statospore Working Group guidelines, and stomatocyst assemblages were significantly different among the three peatlands. In addition, these stomatocyst morphotypes were classified into eight morphology- based functional groups according to morphological traits, such as types of collar and ornamentation. Redun-dancy analyses revealed that stomatocyst assemblages at both morphotype- and functional group-level were significantly correlated with depth to water table, oxidation reduction potential, and morphotype-level composition was further related to electronic conductivity and potassium. Generally, cysts with a complex collar preferred dry hummocks, while large cysts with long spines mainly occurred in wet hollows. This study highlights the usage of chrysophyte stomatocysts as potential bio
... The majority of these are headwater lakes (60%) with highly variable morphology, and surface areas ranging from 0.05 to 120 km 2 . Long term declines in water quality, attributed to land-use change and acid deposition (Wilkinson et al., 1999;Paterson et al., 2001), have been recorded across the region. Although over 90% of monitored lakes in this landscape are considered oligotrophic to mesotrophic (District Municipality of Muskoka, 2015), several (>8%) are eutrophic and experience frequent cyanobacterial blooms (e.g. ...
Potential future changes in lake physical processes (e.g. stratification and freezing) can be assessed through exploring their sensitivity to climate change, and assessing the current vulnerability of different lake types to plausible changes in meteorological drivers. This study quantifies the impacts of climate change and sensitivity of lake physical processes within a large (5100 km ² ) Precambrian Shield catchment in south‐central Ontario. Historic regional relationships are established between climate drivers, lake morphology, and lake physical changes through generalized linear modelling (GLM), and are used to quantify likely changes in timing of ice phenology and lake stratification across 72 lakes under a range of future climate models and scenarios.
In response to projections of increased temperature (ensemble mean of +3.3 °C), both earlier ice‐off and onset of summer stratification were projected, with later ice‐on and fall turnover compared to the baseline. Process sensitivity to climate change varied by lake type; shallower lakes with a smaller volume (less than 15 m deep and less than 0.05 km ³ ) were more sensitive to processes associated with lake heating (stratification onset and ice‐off), and deeper lakes with a larger surface area (greater than 30 m deep and greater than 1000 ha) were more sensitive to processes associated with lake cooling (fall turnover and ice‐on). These results indicate that whereas small lakes are vulnerable to climate warming because of changes that occur in spring and summer, larger lakes are particularly sensitive during the fall. The findings suggest that lake morphology and associated sensitivity should be considered in the development of sustainable lake management strategies. Copyright © 2016 John Wiley & Sons, Ltd.
... Chrysophyte stomatocysts (Smol, 1988 ), and silicascaled chrysophytes (Wilken, Kristiansen & Jürgensen, 1995 ) accumulate in sediments and are used to reconstruct past climate trends, especially in cold regions (Charvet, Vincent & Lovejoy, 2012 ). Previous studies have shown that chrysophytes respond to a variety of environmental changes, including shifts in pH (Duff & Smol 1991; Facher & Schmidt 1996; Wilkinson, Hall & Smol, 1999), trophic status (Zeeb, Duff & Smol, 1990; Zeeb et al. 1994; Wilkinson, Hall & Smol, 1999; Cabala & Piatek, 2004; Charvet, Vincent & Lovejoy, 2012), salinity (Pienitz et al. 1992;), pronounced seasonal changes in light availability (Charvet, Vincent & Lovejoy, 2012 ) and climate (Zeeb & Smol, 1993). Their success is most likely due to their diverse nutritional strategies and ability to produce resistant siliceous resting stages, termed stomatocysts . ...
... Chrysophyte stomatocysts (Smol, 1988 ), and silicascaled chrysophytes (Wilken, Kristiansen & Jürgensen, 1995 ) accumulate in sediments and are used to reconstruct past climate trends, especially in cold regions (Charvet, Vincent & Lovejoy, 2012 ). Previous studies have shown that chrysophytes respond to a variety of environmental changes, including shifts in pH (Duff & Smol 1991; Facher & Schmidt 1996; Wilkinson, Hall & Smol, 1999), trophic status (Zeeb, Duff & Smol, 1990; Zeeb et al. 1994; Wilkinson, Hall & Smol, 1999; Cabala & Piatek, 2004; Charvet, Vincent & Lovejoy, 2012), salinity (Pienitz et al. 1992;), pronounced seasonal changes in light availability (Charvet, Vincent & Lovejoy, 2012 ) and climate (Zeeb & Smol, 1993). Their success is most likely due to their diverse nutritional strategies and ability to produce resistant siliceous resting stages, termed stomatocysts . ...
... Chrysophyte stomatocysts (Smol, 1988), and silicascaled chrysophytes (Wilken, Kristiansen & Jürgensen, 1995) accumulate in sediments and are used to reconstruct past climate trends, especially in cold regions (Charvet, Vincent & Lovejoy, 2012). Previous studies have shown that chrysophytes respond to a variety of environmental changes, including shifts in pH (Duff & Smol 1991;Facher & Schmidt 1996;Wilkinson, Hall & Smol, 1999), trophic status (Zeeb, Duff & Smol, 1990;Zeeb et al. 1994;Wilkinson, Hall & Smol, 1999;Cabala & Piatek, 2004;Charvet, Vincent & Lovejoy, 2012), salinity (Pienitz et al. 1992;, pronounced seasonal changes in light availability (Charvet, Vincent & Lovejoy, 2012) and climate (Zeeb & Smol, 1993). Their success is most likely due to their diverse nutritional strategies and ability to produce resistant siliceous resting stages, termed stomatocysts. ...
... Chrysophyte stomatocysts (Smol, 1988), and silicascaled chrysophytes (Wilken, Kristiansen & Jürgensen, 1995) accumulate in sediments and are used to reconstruct past climate trends, especially in cold regions (Charvet, Vincent & Lovejoy, 2012). Previous studies have shown that chrysophytes respond to a variety of environmental changes, including shifts in pH (Duff & Smol 1991;Facher & Schmidt 1996;Wilkinson, Hall & Smol, 1999), trophic status (Zeeb, Duff & Smol, 1990;Zeeb et al. 1994;Wilkinson, Hall & Smol, 1999;Cabala & Piatek, 2004;Charvet, Vincent & Lovejoy, 2012), salinity (Pienitz et al. 1992;, pronounced seasonal changes in light availability (Charvet, Vincent & Lovejoy, 2012) and climate (Zeeb & Smol, 1993). Their success is most likely due to their diverse nutritional strategies and ability to produce resistant siliceous resting stages, termed stomatocysts. ...
The fabric of sedimentary rocks in lacustrine archives usually contains long and continuous proxy records of biological, chemical and physical parameters that can be used to study past environmental and climatic variability. Here we propose an innovative approach to sedimentary facies analysis based on a coupled geomicrobiological and sedimentological study using high-resolution microscopic techniques in combination with mineralogical analyses. We test the applicability of this approach on Lake Son Kul, a high alpine lake in central Tien Shan (Kyrgyzstan) by looking at the mineral fabric and microbial communities observed down to the nanoscale. The characterization of microbe–mineral interactions allows the origin of four carbonate minerals (e.g. aragonite, dolomite, Mg-calcite, calcite) to be determined as primary or diagenetic phases in Lake Son Kul. Aragonite was mainly of primary origin and is driven by biological activity in the epilimnion, whereas diagenetic minerals such as Mg-calcite, calcite, dolomite and pyrite were triggered by bacterial sulphate reduction and possibly by methanotrophic archaea. A new morphotype of aragonite (i.e. spherulite-like precursor) occurs in Unit IV (c. 7100–5000 cal. BP) associated with microbial mat structures. The latter enhanced the preservation of viral relics, which have not yet been reported in Holocene lacustrine sediments. This study advocates that microbe–mineral interactions screened down to the nanoscale (e.g. virus-like particles) can be used successfully for a comprehensive description of the fabric of laminated lake sediments. In this sense, they complement traditional facies sedimentology tools and offer valuable new insights into: (1) the study of microbial and viral biosignatures in Quaternary sediments; and (2) palaeoenvironmental reconstructions.
... These unidentified stomatocyst morphotypes are grouped together and categorized simply as chrysophyte stomatocysts and assigned numbers as described by the guidelines of the International Statospore Working Group (Cronberg & Sandgren 1986). Although calibration sets (Charles & Smol 1994) have been developed for use in models correlating stomatocyst morphotypes to specific physical and chemical lake conditions (Zeeb & Small 1995;Duff et al. 1997;Wilkinson et al. 1999;Pla et al. 2003), a clearer picture of chrysophyte distribution patterns would emerge if vegetative stages and cysts were linked. ...
There is an extensive literature on chrysophyte stomatocysts from diverse habitats and their use as paleolimnetic indicators of past environmental conditions in lakes. The majority of these cysts are unidentified, and more laboratory studies are needed to link stomatocyst morphotypes to vegetative stages. A laboratory procedure that resulted in stomatocyst production in the chrysophyte alga Ochromonas pinguis (Chrysophyceae) was tested to determine if the protocol would also stimulate the production of stomatocysts in six other chrysophytes. Chrysolepidomonas dendrolepidota, Chrysosaccus cf. sphaericus, Dermatochrysis sp., Synura cf. americana, Synura cf. macropora and a second species of Ochromonas all produced stomatocysts within two to three weeks. Morphology of the stomatocyst was described using scanning electron microscopy (SEM). This was the first report of stomatocysts from Chrysosaccus and the first SEM description of O. pinguis cysts. These autecological studies provide a greater linkage between sediment stomatocysts and their biological origin, strengthening the interpretive value of these microfossils and broadening our understanding of chrysophyte biogeography.
... Recently, top-bottom paleolimnological studies in the Muskoka-Haliburton region have been used to infer changes in lakewater pH, total phosphorus (diatoms, Hall and Smol 1996; chrysophyte cysts, Wilkinson et al. 1999), and lakewater oxygen (chironomids, Quinlan et al. 1998). Results from these studies suggest that changes in water quality have been minimal in many of the Muskoka lakes. ...
... Results from these studies suggest that changes in water quality have been minimal in many of the Muskoka lakes. For example, Hall and Smol (1996) and Wilkinson et al. (1999) determined that the pH and total phosphorus of~60% of lakes examined had changed less than the root mean squared error (RMSE) of the predictive models since preindustrial times. ...
... However, other paleolimnological evidence suggests that these impacts have been Table 1. small since preindustrial times (Hall and Smol 1996;Wilkinson et al. 1999). Scaled chrysophytes have been shown to be sensitive indicators of lake acidification (Smol 1995), often showing inferred pH changes greater than those from other indicators (e.g., diatoms). ...
Scaled chrysophytes preserved in modern and fossil sediment samples from lakes in south-central Ontario were examined to evaluate changes in water quality since preindustrial times. Redundancy analysis determined that chrysophyte distributions were related to a primary gradient of pH, alkalinity, and ion concentration (λ1 = 0.26). A 117-lake reconstruction model from Ontario, the Adirondacks, and northeastern U.S.A. was used to infer the lakewater pH of present-day and preindustrial samples. A comparison of predicted and measured pH values of modern samples, analog matching, and an examination of inferences from triplicate cores in four lakes suggested that the inferences were reliable. Reconstructions indicated that presently acidic lakes (pH < 6) had acidified, whereas lakes with measured pH > 7 had become more alkaline. In comparison to other acid-sensitive regions, however, the overall change was small. The relatively short pH gradient, higher preindustrial pH values, and amount of acid deposition are factors that may explain these trends. Finally, we introduce a novel, multi-indicator reconstruction model, which provides an average of environmental reconstructions from diatom, chrysophyte cyst, and scaled chrysophyte assemblages. This model performed as well or better than the individual inferences when used to predict the pH of modern samples.
... This high cumulative percentage suggests that the distribution of species present is not random and can be explained by environmental variables. Association of [SO 4 2-], [Mg 2+ ], [K + ], longitude, and WA with the first axis ( Fig. 2), in addition to the known acidic deposition in this area, suggests that this axis may be interpreted as a proxy for acid neutralizing capacity (ANC), reflecting alkalinity and pH gradients (Wilkinson et al. , 1998. The importance of [TN] and shoreline development to the second axis (Fig. 2) indicates it may represent a gradient of lake productivity (Wilkinson et al. , 1998. ...
... Association of [SO 4 2-], [Mg 2+ ], [K + ], longitude, and WA with the first axis ( Fig. 2), in addition to the known acidic deposition in this area, suggests that this axis may be interpreted as a proxy for acid neutralizing capacity (ANC), reflecting alkalinity and pH gradients (Wilkinson et al. , 1998. The importance of [TN] and shoreline development to the second axis (Fig. 2) indicates it may represent a gradient of lake productivity (Wilkinson et al. , 1998. ...
... Group 1 and 2 cysts are negatively correlated with [SO 4 2-], , pH, morphometric, and conductivity variables. Conversely, group 3 and 4 cysts are positively correlated with pH, conductivity, [SO 4 2-], and [NO 3 -] (Wilkinson 1997(Wilkinson , 1998. ...
Chrysophycean stomatocyst morphotypes were identified and enumerated from the sediments of 55 Muskoka-Haliburton south-central Ontario lakes. Principal components analysis (PCA) and TWINSPAN cluster analysis showed that the distribution of cyst assemblages was most closely related to lake water pH. Cyst abundance varied with lake trophic status, decreasing in highly productive lakes. The diversity of the observed cyst assemblages was similar to that seen in other stomatocyst studies from temperate regions, with a total of 246 morphotypes noted. The Muskoka-Haliburton cyst flora contained a high proportion (22.8%) of as yet undescribed morphotypes and an abundance of cysts ornamented with circuli and small ridges. Fifty-six previously unidentified morphotypes were observed, 29 of which were studied in detail using scanning electron microscopy, and described using International Statospore Working Group guidelines. Six variants of common morphotypes, characterized by the presence of a siliceous envelope, are also described. Twelve new distinct morphotypes observed only using light microscopy are documented as unidentified forms.Key words: Chrysophyceae, stomatocyst, taxonomy, Muskoka-Haliburton, Ontario, lakes, paleolimnology.
