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  • 1
    Electronic Resource
    Electronic Resource
    Diatom-salinity relationships in 111 lakes from the Interior Plateau of British Columbia, Canada: the development of diatom-based models for paleosalinity reconstructions (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 197-221 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; paleolimnology ; paleoclimatology ; salinity ; athalassic ; British Columbia ; CCA ; transfer function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatoms were identified and enumerated from the surface sediments of 111 lakes, 45 from the Kamloops region and 66 from the Cariboo/Chilcotin region, located on the southern Interior Plateau of British Columbia, Canada. This paper is an extension of another study which investigated the relationship of diatoms to salinity and ionic composition in 65 lakes from the Cariboo/Chilcotin region. The 111 lakes spanned a large gradient in salinity, ranging from fresh through hypersaline (late-summer salinity values ranged from 0.04 to 369 g l−1), and included both carbonate- and sulphate-dominated lakes with sodium and magnesium as the dominant cations. The Kamloops region had more sulphate-dominated, hypersaline lakes and fewer carbonate-rich lakes than the Cariboo/Chilcotin region. Most lakes had higher salinities in the late-summer compared to the spring. Both salinity and brine-type were important variables that could explain the different diatom assemblages present in the lakes. The majority of diatom taxa had salinity optima in the freshwater to subsaline range (〈3 g l−1), and the taxa displayed a range of both narrow and broad tolerances along the salinity gradient. Weighted-averaging regression and calibration, and maximum likelihood techniques were used to develop salinity inference models from the diatom assemblages based on their relationship to the spring, late-summer and average lakewater salinity measurements. Simple weighted-averaging (WA) models generally produced the same or lower bootstrapped RMSEs of prediction than weighted-averaging with tolerance downweighting (WA(tol)) in the two regional and the combined datasets. Weighted averaging partial least squares (WA-PLS) showed little or no improvement in the predictive abilities of the datasets, as judged by the jackknifed RMSE of prediction. In all cases, the combined dataset of 102 lakes performed better than either of the smaller regional datasets, with relatively little difference between spring, average and late-summer salinity models. The maximum likelihood models gave lower apparent RMSEs of prediction in comparison to other methods; however, independent validation of this technique using methods such as bootstrapping were not undertaken because of the computer intensive nature of such analyses. These diatom-based salinity models are now available for reconstructing salinity and climatic trends from appropriately chosen closed-basin lakes in the Interior region of British Columbia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678021
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  • 2
    Electronic Resource
    Electronic Resource
    High-resolution paleoecological analysis of recent disturbance in a southern Chilean Nothofagus forest (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 235-252 
    Details
    ISSN: 1573-0417
    Keywords: fire ; disturbance ; paleoecology ; paleolimnology ; pollen ; chrystophytes ; charcoal ; Chile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A 1600 year paleoecological record of environmental change is developed from a small lake in the Nothofagus forest of southern Chile (45.5°S, 72°W). High resolution fossil pollen, charcoal, sedimentological, and chrysophycean stomatocyst analyses are used to investigate the impacts of natural and anthropogenic disturbances on terrestrial and lacustrine environments. Chronological control is based on a combination of 210Pb and 14C dating. Temporal resolution during the past 150–200 yr is ca. 8 yr/sample. The macroscopic charcoal record correlates very closely with historical and dendroecological records of 20th century anthropogenic burning in this region. The chrysophyte stratigraphy indicates that this burning had immediate impacts on the lake itself, while the pollen record provides evidence for a succession of vegetation changes lagging slightly behind the disturbance. These palynological changes are very similar to the pollen signal of European disturbance in northeastern North America. Pre-European shifts in chrysophyte assemblages may be due to the influence of earthquake activity on the lake, though there is no corroborative evidence in the pollen or charcoal records. This study demonstrates that high resolution paleoecological methods can be used to help bridge the temporal gap between traditional ecological and paleoecological studies of environmental change in the temperate forests of southern South America.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007950905200
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  • 3
    Electronic Resource
    Electronic Resource
    Utility of scaled chrysophytes for inferring lakewater pH in northern New England lakes (1990)
    Springer
    Journal of paleolimnology 3 (1990), S. 269-286 
    Details
    ISSN: 1573-0417
    Keywords: scaled chrysophytes ; pH reconstructions ; algal microfossils ; lake acidification ; paleolimnology ; New England ; CCA ; DCA ; PCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Scaled chrysophytes in the surface sediments of 58 soft-water northern New England lakes were analyzed to assess their usefulness for inferring pH. The distributions of many taxa are correlated with lakewater pH and associated variables. Canonical correspondence analysis (CCA) and clustering grouped chrysophyte taxa according to their distributions along the pH gradient. For example, Chrysodidymus synuroideus, Mallomonas hindonii, and M. hamata commonly occur in acidic waters (pH〈5.5), whereas M. caudata and M. pseudocoronata are common in circumneutral to alkaline waters. Of the five predictive models developed to infer pH, CCA based calibration had the lowest standard error (0.35 pH units). A CCA based predictive model was also developed to infer total alkalinity. The study provides strong evidence that, in the absence of past measured pH data, stratigraphic studies of sedimentary chrysophyte scales will provide accurate reconstructions of pH in northern New England lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219462
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  • 4
    Electronic Resource
    Electronic Resource
    An expanded weighted-averaging model for inferring past total phosphorus concentrations from diatom assemblages in eutrophic British Columbia (Canada) lakes (1995)
    Springer
    Journal of paleolimnology 14 (1995), S. 49-67 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; eutrophication ; lake management ; paleolimnology ; British Columbia ; lakes ; phosphorus ; training sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Eighteen lakes were added to a published training set of 46 British Columbia (BC) lakes in order to expand the original range of total phosphorus (TP) concentrations. Canonical correspondence analysis (CCA) was used to analyze the relationship between diatom assemblages and environmental variables. Specific conductivity and [TP] each explained significant (P≤0.05) directions of variance in the distribution of the diatoms. The relationship between diatom assemblages and [TP] was sufficiently strong to warrant the development of a weighted-averaging (WA) regression and calibration model that can be used to infer past trophic status from fossil diatom assemblages. The relationship between observed and inferred [TP] was not improved by the addition of more eutrophic lakes, however the [TP] range and the number of taxa used in the transfer function are now superior to the original model. Diatom species assemblages changed very little in lakes with TP concentrations greater than 85 µg 1−1, so we document the development of a model containing lakes with TP≤85 µg 1−1. The updated model uses 59 training lakes and covers a range of species optima from 6 to 41.9 µg 1−1 TP, and a total of 150 diatom taxa. The updated inference model provided a more realistic reconstruction of the anthropogenic history of a highly eutrophic BC lake. The model can now be used to infer past nutrient conditions in other BC lakes in order to assess changes in trophic status.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682593
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  • 5
    Electronic Resource
    Electronic Resource
    Patterns of pH change inferred from chrysophyte microfossils in Adirondack and northern New England lakes (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 31-41 
    Details
    ISSN: 1573-0417
    Keywords: paleolimnology ; lake acidification ; scales ; chrysophytes ; New England ; Adirondacks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The silica-scaled chrysophytes are being used increasingly in paleolimnological studies of lake acidification. This study compares the distribution of scaled chrysophytes in the surface sediment of a calibration set of lakes from the Adirondack Park and from northern New England. With the exception of two taxa, species distributions with respect to pH are similar in the two regions. The stratigraphic distribution of chrysophytes is then compared in five Adirondack and three New England lakes. All the presently acid lakes indicate recent lake acidification, with more acid tolerant chrysophytes increasing in relative frequency in the recent sediments. Because the timing of these species changes is unrelated to any watershed disturbances that may have occurred in the lakes' catchments, atmospheric deposition of acids is believed responsible for these recent pH changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208297
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  • 6
    Electronic Resource
    Electronic Resource
    Paleolimnological investigation of the effects of road salt seepage on scaled chrysophytes in Fonda Lake, Michigan (1991)
    Springer
    Journal of paleolimnology 5 (1991), S. 263-266 
    Details
    ISSN: 1573-0417
    Keywords: scaled chrysophytes ; road salt ; Fonda Lake ; Michigan ; paleolimnology ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Chrysophyte scales were identified and enumerated from the recent sediments of Fonda Lake, Michigan. This lake has undergone marked salinification due to chloride intrusion from an adjacent salt-storage facility established in 1953. From 1950 to 1980, Mallomonas caudata dominated at all levels; this taxon appears to be chloride-indifferent. M. elongata and M. pseudocoronata appeared to be chloride-intolerant as they declined drastically in abundance when chloride levels attained a maximum (ca. 1968–1972). M. tonsurata, on the other hand, was more competitive during this period of maximum [Cl\s-]. This preliminary study suggests that chrysophyte scales may be useful paleoindicators of salinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00200349
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  • 7
    Electronic Resource
    Electronic Resource
    Scaled chrysophytes and pH inference models: the effects of converting scale counts to cell counts and other species data transformations (1993)
    Springer
    Journal of paleolimnology 9 (1993), S. 147-153 
    Details
    ISSN: 1573-0417
    Keywords: scaled chrysophytes ; Synurophyceae ; pH ; weighted-averaging ; Adirondack Park (New York) ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Predictive pH models developed using scaled chrysophytes (Synurophyceae, Chrysophyceae) have thus far been based on the relative abundance of scales and not whole cells. This paper examines the effects of transforming scale to cell numbers on the predictive abilities of pH inference models, and the effects of logarithmic and square-root transformations of the species data on the predictive abilities of pH inference models. Very similar pH inference models were developed based on either the relative abundance of scales or cells. Thus, in this data-set, there appears to be no statistical advantage in transforming raw scale counts to cell counts prior to calculating the relative abundances. However, if one wishes to compare paleochrysophyte populations to actual long-term limnological chrysophyte collections, a scale-to-cell transformation would be desirable. Logarithmic and square-root transformations of the species data improve the pH inference models. These transformations increase the effective number of occurrences of chrysophyte taxa when compared to the untransformed scale and cell pH models. The logarithmic and square-root transformations improve the pH inference models because the dominant taxa, which are often pH generalists, are down-weighted in comparison to the more pH specialist, sub-dominant taxa. We suggest researchers use either a logarithmic or square-root transformation on chrysophyte scale data to improve quantitative reconstructions of lakewater pH and possibly other variables.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00677516
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  • 8
    Electronic Resource
    Electronic Resource
    Variability in diatom and chrysophyte assemblages and inferred pH: paleolimnological studies of Big Moose Lake, New York, USA (1991)
    Springer
    Journal of paleolimnology 5 (1991), S. 267-284 
    Details
    ISSN: 1573-0417
    Keywords: variability ; diatoms ; chrysophytes ; acidification ; paleolimnology ; Adirondacks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We measured variability in the composition of diatom and chrysophyte assemblages, and the pH inferred from these assemblages, in sediment samples from Big Moose Lake, in the Adirondack Mountains of New York. Replicate samples were analyzed from (1) a single sediment core interval, (2) 12 different intervals from each of 3 separate cores, and (3) 10 widely spaced surface sediment samples (0–1 cm). The variability associated with sample preparation (subsampling, processing, and counting) was relatively small compared to between-core and within-lake variability. The relative abundances of the dominant diatom taxa varied to a greater extent than those of the chrysophyte scale assemblages. Standard deviations of pH inferences for multiple counts from the same sediment interval from diatom, chrysophyte, and diatom plus chrysophyte inference equations were 0.04 (n=8), 0.06 (n=32), and 0.06 (n=8) of a pH unit, respectively. Stratigraphic analysis of diatoms and chrysophytes from three widely spaced pelagic sediment cores provided a similar record of lake acidification trends, although with slight differences in temporal rates of change. Average standard deviations of pH inferences from diatom, chrysophyte and diatom plus chrysophyte inference equations for eight sediment intervals representing similar time periods but in different cores were 0.10, 0.20, and 0.09 pH unit, respectively. Our data support the assumption that a single sediment core can provide an accurate representation of historical change in a lake. The major sources of diatom variability in the surface sediments (i.e., top 1.0 cm) were (1) differences in diatom assemblage contributions from benthic and littoral sources, and (2) the rapid change in assemblage composition with sediment depth, which is characteristic of recently acidified lakes. Because scaled chrysophytes are exclusively planktonic, their spatial distribution in lake sediments is less variable than the diatom assemblages. Standard deviations of pH inferences for 10 widely spaced surface sediment samples from diatom, chrysophyte and diatom plus chrysophyte inference equations were 0.21, 0.09, and 0.16 of a pH unit, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00200350
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  • 9
    Electronic Resource
    Electronic Resource
    A weighted-averaging regression and calibration model for inferring lakewater salinity using chrysophycean stomatocysts from lakes in western Canada (1995)
    Springer
    International journal of salt lake research 4 (1995), S. 1-23 
    Details
    ISSN: 1573-8590
    Keywords: British Columbia ; chrysophytes ; paleolimnology ; saline lakes ; stomatocysts ; weighted-averaging model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Chrysophycean stomatocysts were identified and enumerated from the surface sediments of 60 lakes located on the Interior Plateau of British Columbia. The lakes span a salinity gradient from freshwater to hypersaline (0.0–92.4 g L−1), with the majority being fresh to hyposaline. One hundred and ten stomatocyst morphotypes, almost all of which were previously described, were identified from the lake sediments. The first axis of direct gradient analysis, which was highly significant, was essentially a salinity axis (i.e. [Ca], [Mg], [K], [Na], [SO4], [DIC], and [Cl]). Most cysts were found to have fairly broad tolerances, with the narrowest tolerances occurring among morphotypes with the lowest salinity optima. Weighted-averaging regression and calibration techniques were used to develop an inference model to measure the relationship between measured average lakewater salinity and stomatocyst inferred salinity (apparent r2=0.80). Simple weighted-averaging produced a model with a lower bootstrapped RMSE of prediction than weighted-averaging with tolerance downweighting. These data indicate that chrysophyte stomatocysts are useful quantitative indicators of past lakewater salinity (in the freshwater to hyposaline range) in B.C. lakes, and can be used to strengthen the interpretations from diatom-inference models already developed from the same region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01992411
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  • 10
    Electronic Resource
    Electronic Resource
    Chrysophyte scales recorded in lake sediments from eastern Finland (1988)
    Springer
    Hydrobiologia 161 (1988), S. 237-243 
    Details
    ISSN: 1573-5117
    Keywords: paleolimnology ; Mallomonas ; scaled chrysophytes ; environmental indicators ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chrysophyte (mallomonadacean) scales were examined from the surface sediments of 18 lakes from eastern Finland, representing a wide range of limnological characteristics. Scales were always well preserved and 23 taxa were observed. The relative frequencies of the dominant taxa were plotted relative to the average autumn lakewater pH. The distribution of chrysophyte species in the calibration set was ordinated by means of DECORANA analysis. The occurrence of these species appeared to be closely related to pH, colour and nutrients in the ordinated lake groups. Chrysophyte scales are potentially useful environmental and paleolimnological indicators in eastern Finland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044114
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