scholarly journals Increased relative abundance of colonial scaled chrysophytes since pre-industrial times in minimally disturbed lakes from the Experimental Lakes Area, Ontario

2018 ◽  
Vol 75 (9) ◽  
pp. 1465-1476 ◽  
Author(s):  
Graham R. Mushet ◽  
Karlee Flear ◽  
Brendan Wiltse ◽  
Andrew M. Paterson ◽  
Brian F. Cumming
Keyword(s):  
Relative Abundance ◽  
Sediment Cores ◽  
Experimental Lakes Area ◽  
Scaled Chrysophytes ◽  
Modern Distribution ◽  
Multiple Processes ◽  
High Nutrient ◽  
Northwest Ontario ◽  
Physicochemical Data ◽  
Warm Lakes

A top–bottom paleolimnological analysis of 30 undisturbed lakes in the Experimental Lakes Area (ELA) in northwest Ontario showed marked increases in the relative abundance of colonial scaled chrysophyte taxa in most lakes since pre-industrial times. The increase in abundance of colonial taxa was primarily driven by Synura sphagnicola in small, high-nutrient, and warm lakes. The colonial taxa Synura petersenii and Synura echinulata also increased in the deeper study lakes. Detailed analysis of sediment cores from six lakes revealed that these changes occurred in the early to mid-1900s. Based on the modern distribution of scaled chrysophytes relative to lake physicochemical data, we propose multiple processes that may be contributing to these changes, such as changes in lake thermal properties and historical changes in the flux of important particles and solutes to lakes. Additional mechanisms that may contribute to the observed changes are discussed, including trophic interactions and changes in limnetic pCO2. Because the ELA is relatively undisturbed, our findings provide important information on the drivers responsible for increases in colonial chrysophyte abundance, which have been documented in studies of lakes in central Ontario and northeast United States.

Introduction to the Northwest Ontario Lake Size Series (NOLSS)

1992 ◽  
Vol 49 (12) ◽  
pp. 2434-2444 ◽  
Author(s):  
E. J. Fee ◽  
R. E. Hecky
Keyword(s):  
Turbulent Energy ◽  
Morphological Similarity ◽  
Experimental Lakes Area ◽  
Mixing Depth ◽  
Biological Communities ◽  
Renewal Time ◽  
Northwest Ontario ◽  
Per Se ◽  
Lake Size ◽  
Size Series

The rationale, design, and limitations of the Northwest Ontario Lake Size Series (NOLSS) research program are described. The primary purpose of NOLSS is to discover how lake size per se influences limnological and fisheries phenomena, so that conclusions drawn from studies of particular lakes can be rigorously scaled and applied to lakes of other sizes. NOLSS consists of six lakes located in a remote wilderness region of Northwest Ontario. These lakes were chosen for their geological, hydrological, and morphological similarity (Canadian Shield geology; water renewal time> 5 yr; fully stratified in summer), but they form an exponential gradient in surface area (from 89 to 34 700 ha.) Associated with this gradient of lake size are gradients of physical properties (turbulent energy, mixing depth, thermal behaviour) to which biological communities must adapt. NOLSS fills the conspicuous gap in size that separates two well-studied groups of lakes in Northwest Ontario: the Experimental Lakes Area (ELA), where whole-lake manipulation experiments are performed, and the Laurentian Great Lakes (Nipigon, Superior), where these experiments find some of their most important applications.

Fossil Midge Associations in Relation to Trophic and Acidic State of the Turkey Lakes

1988 ◽  
Vol 45 (S1) ◽  
pp. s136-s144 ◽  
Author(s):  
M. G. Johnson ◽  
O. C. McNeil
Keyword(s):  
Species Composition ◽  
Total Phosphorus ◽  
Relative Abundance ◽  
Sediment Cores ◽  
Fish Communities ◽  
Taxonomic Composition ◽  
Near Surface ◽  
Surface Reduction ◽  
Chaoborus Americanus ◽  
Polymictic Lake

Most changes in profiles of relative abundance of Chironomus, Sergentia, Procladius, Heterotrissocladius, Micropsectra, Tanytarsus, and other taxa in dated sediment cores suggested a trend to more oligotrophy conditions at present in four dimictic lakes, but not in the single polymictic lake in which species composition was least variable temporally. Decreased numbers of chironomids and chaoborids toward the present indicated declining productivity in all five lakes. Total phosphorus concentrations in sediments declined through these periods of inferred greater oligotrophy. Most of these trends were probably not caused by anthropogenic acidification because they began up to 130 yr B.P. and they were sometimes duplicated even deeper in sediment cores. Furthermore, taxa common in acidified lakes elsewhere did not increase in these lakes. Recent acidification may have affected taxonomic composition and diversity of chironomids in the headwater lake, the only lake which showed a near-surface reduction in members of the tribe Tanytarsini, and the ratio of taxa to individuals. Chaoborus americanus occurred at high densities throughout the cores from the two upper lakes, indicating that these lakes probably never had fish communities.

scholarly journals Population Structure and Phylogenetic Characterization of Marine Benthic Archaea in Deep-Sea Sediments

1999 ◽  
Vol 65 (10) ◽  
pp. 4375-4384 ◽  
Author(s):  
Costantino Vetriani ◽  
Holger W. Jannasch ◽  
Barbara J. MacGregor ◽  
David A. Stahl ◽  
Anna-Louise Reysenbach
Keyword(s):  
Population Structure ◽  
Relative Abundance ◽  
Deep Sea ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Sediment Cores ◽  
Rrna Genes ◽  
Phylogenetic Characterization ◽  
Oligonucleotide Hybridization ◽  
Deep Sea Sediments ◽  
Phylogenetic Lineages

ABSTRACT During the past few years Archaea have been recognized as a widespread and significant component of marine picoplankton assemblages and, more recently, the presence of novel archaeal phylogenetic lineages has been reported in coastal marine benthic environments. We investigated the relative abundance, vertical distribution, phylogenetic composition, and spatial variability ofArchaea in deep-sea sediments collected from several stations in the Atlantic Ocean. Quantitative oligonucleotide hybridization experiments indicated that the relative abundance of archaeal 16S rRNA in deep-sea sediments (1500 m deep) ranged from about 2.5 to 8% of the total prokaryotic rRNA. Clone libraries of PCR-amplified archaeal rRNA genes (rDNA) were constructed from 10 depth intervals obtained from sediment cores collected at depths of 1,500, 2,600, and 4,500 m. Phylogenetic analysis of rDNA sequences revealed the presence of a complex archaeal population structure, whose members could be grouped into discrete phylogenetic lineages within the two kingdoms, Crenarchaeota and Euryarchaeota. Comparative denaturing gradient gel electrophoresis profile analysis of archaeal 16S rDNA V3 fragments revealed a significant depth-related variability in the composition of the archaeal population.

Reconstruction of Holocene lake level from diatoms, chrysophytes and organic matter in a drainage lake from the Experimental Lakes Area (northwestern Ontario, Canada)

2008 ◽  
Vol 69 (2) ◽  
pp. 292-305 ◽  
Author(s):  
Kathleen R. Laird ◽  
Brian F. Cumming
Keyword(s):  
Organic Matter ◽  
Lake Level ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Matter Content ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Large Fluctuations ◽  
Near Shore ◽  
Partial View

A paleolimnological study of lake-level changes in Lake 239 (Rawson Lake), a headwater lake in the Experimental Lakes Area in northwestern Ontario, indicates large fluctuations have occurred over the Holocene. Analyses are based on diatoms, the proportion of chrysophyte scales to diatoms and organic matter content from near-shore sediment cores. Quantitative estimates of lake level are based on a diatom-inferred depth model that was developed from surficial sediments collected along several transects in Lake 239. Declines of ∼ 1–3 m occurred during the late Holocene, whereas declines of at least 8 m occurred during the more arid mid-Holocene. These results provide the first substantive evidence of large declines in lake level in northwestern Ontario during the mid-Holocene. Conditions during the mid-Holocene may provide a partial view of future conditions under increasing global temperatures.

When Did Acid-Sensitive Adirondack Lakes (New York, USA) Begin to Acidify and Are They Still Acidifying?

1994 ◽  
Vol 51 (7) ◽  
pp. 1550-1568 ◽  
Author(s):  
B. F. Cumming ◽  
K. A. Davey ◽  
J. P. Smol ◽  
H. J. B. Birks
Keyword(s):  
New York ◽  
Transfer Function ◽  
Species Composition ◽  
Acidic Deposition ◽  
Sediment Cores ◽  
Scaled Chrysophytes ◽  
Sulfate Deposition ◽  
Ph Values ◽  
Water Ph ◽  
Adirondack Lakes

A transfer function was used to reconstruct pH values of 20 low-alkalinity Adirondack Park lakes based on the species composition of scaled chrysophytes (Chrysophyceae, Synurophyceae) in stratigraphie intervals from 210Pb-dated sediment cores. Approximately 80% of the lakes acidified since preindustrial times. Four categories of lake response to acidic deposition were identified: (i) lakes that showed little or no evidence of acidification since preindustrial times, (ii) lakes with preindustrial pH values between 5 and 6 that began to acidify ca. 1900, (iii) "naturally" acidic lakes that acidified even further ca. 1900, and (iv) lakes with preindustrial pH values around 6 that acidified ca. 1930–50. Lakes that acidified ca. 1900 were generally smaller, higher elevation lakes with lower preindustrial pH values than lakes in category i or iv. These patterns are consistent with the acidic deposition hypothesis of recent lake acidification. Our results indicated that "critical" sulfate deposition loads for Adirondack lakes that started to acidify ca. 1900 and ca. 1950 are between 5–10 and 20–25 kg∙ha−1∙yr−1, respectively. Post-1970 trends in lake water pH have been small and variable, suggesting that low-alkalinity Adirondack lakes have been relatively unresponsive to the post-1970 declines in sulfate deposition.

Changes in the prairie–forest ecotone in northwest Ontario (Canada) across the Holocene

2021 ◽  
pp. 1-12
Author(s):  
Donya C. Danesh ◽  
Cale A.C. Gushulak ◽  
Melissa T. Moos ◽  
Moumita Karmakar ◽  
Brian F. Cumming
Keyword(s):  
Climate Changes ◽  
Transfer Functions ◽  
Sediment Cores ◽  
Lake Levels ◽  
Diatom Assemblages ◽  
Site Specific ◽  
The Holocene ◽  
Arboreal Pollen ◽  
Northwest Ontario ◽  
Forest Ecotone

Abstract Pollen and diatom assemblages from well-dated sediment cores from three lakes forming a west-to-east transect across the boreal forest in northwest Ontario (Canada) were used to evaluate the timing and nature of the movement of the prairie–forest ecotone (PFE) across the Holocene. Changes in vegetation, temperature, and effective moisture were inferred from pollen and pollen-based transfer functions. Analyses indicated site-specific vegetational and climate changes across short spatial distances, with prolonged prairie-like conditions during the middle Holocene at the westernmost site. Increased reconstructed temperatures at this westernmost site occurred from ~9000 to 3000 cal yr BP, alongside increases in diatom-inferred lake levels beginning at ~6000 cal yr BP. The abundance of Quercus peaked concurrently with rising lake levels before declining to trace levels by ~3000 cal yr BP. Increases in the abundance of non-arboreal pollen between ~8500 and ~4500 cal yr BP at the more eastern lakes suggest relatively delayed and truncated PFE influence, before the reestablishment of primarily boreal taxa by ~4500 cal yr BP, coincident with diatom-inferred increases in lake levels. This study shows that the PFE moved both farther east and north than previously determined, but generally agrees with established patterns in vegetation from other studied regions along the PFE.

Assessment of the effects of logging, forest fires and drought on lakes in northwestern Ontario: a 30-year paleolimnological perspective

1998 ◽  
Vol 28 (10) ◽  
pp. 1546-1556 ◽  
Author(s):  
Andrew M Paterson ◽  
Brian F Cumming ◽  
John P Smol ◽  
Jules M Blais ◽  
Robert L France
Keyword(s):  
Forest Fires ◽  
Large Scale ◽  
Sediment Cores ◽  
Timber Harvesting ◽  
Species Assemblages ◽  
Gradual Change ◽  
Scaled Chrysophytes ◽  
Northwestern Ontario ◽  
Time Period ◽  
Regional Influence

The frequency and intensity of large-scale watershed disturbances (e.g., clearcuts and wildfires) is increasing in northwestern Ontario. Timber harvesting and wildfires have been shown to alter water quantity and quality in stream ecosystems. Unfortunately, scientific studies of these impacts on lakes are considerably rarer. Using paleolimnological techniques, we examined the remains of scaled chrysophytes in sediment cores from four lakes that have had the majority of their watersheds clearcut, two lakes that have had large forest fires in their watersheds, and two lakes that have had minimal watershed disturbance. Lakes in this study showed minor changes in the composition of scaled chrysophytes at a temporal resolution of 2-4 years, despite removal of over 90% of the forest. Furthermore, temporal variability in the species assemblages were similar in all lakes. A gradual change in the species assemblages of all lakes suggested a regional influence may have been responsible. We hypothesize that hydrological changes brought about by a regional drought from 1970 to 1990 may have exerted an overriding influence on lakes over this time period.

Influence of increased nutrient supply on Microcystis aeruginosa at cellular and proteomic levels

2020 ◽  
Vol 85 ◽  
pp. 47-58
Author(s):  
Y Jiang ◽  
Y Liu
Keyword(s):  
Microcystis Aeruginosa ◽  
Regulatory Protein ◽  
Acid Synthesis ◽  
Nutrient Supply ◽  
Nitrogen Supply ◽  
Nitrogen And Phosphorus ◽  
Comprehensive Description ◽  
Amino Acid Synthesis ◽  
High Nutrient ◽  
Proteomic Responses

Various studies have observed that increased nutrient supply promotes the growth of bloom-forming cyanobacteria, but only a limited number of studies have investigated the influence of increased nutrient supply on bloom-forming cyanobacteria at the proteomic level. We investigated the cellular and proteomic responses of Microcystis aeruginosa to elevated nitrogen and phosphorus supply. Increased supply of both nutrients significantly promoted the growth of M. aeruginosa and the synthesis of chlorophyll a, protein, and microcystins. The release of microcystins and the synthesis of polysaccharides negatively correlated with the growth of M. aeruginosa under high nutrient levels. Overexpressed proteins related to photosynthesis, and amino acid synthesis, were responsible for the stimulatory effects of increased nutrient supply in M. aeruginosa. Increased nitrogen supply directly promoted cyanobacterial growth by inducing the overexpression of the cell division regulatory protein FtsZ. NtcA, that regulates gene transcription related to both nitrogen assimilation and microcystin synthesis, was overexpressed under the high nitrogen condition, which consequently induced overexpression of 2 microcystin synthetases (McyC and McyF) and promoted microcystin synthesis. Elevated nitrogen supply induced the overexpression of proteins involved in gas vesicle organization (GvpC and GvpW), which may increase the buoyancy of M. aeruginosa. Increased phosphorus level indirectly affected growth and the synthesis of cellular substances in M. aeruginosa through the mediation of differentially expressed proteins related to carbon and phosphorus metabolism. This study provides a comprehensive description of changes in the proteome of M. aeruginosa in response to an increased supply of 2 key nutrients.

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